Shellac4partsBorax1partWater16parts
Borax and shellac must be put into a clean pot filled two thirds with water and boiled for an hour. As the water boils away it must be replaced. When the shellac has been mostly dissolved, the mass is removed from the fire, cooled, and filtered through a clean cloth to separate the undissolved portions of the shellac.
This solution can be kept for years in a tightly closed glass. To color it, a portion is to be cooked in a copper or iron ladle till it is thick as honey. Fine lampblack or vermilion is stirred in till the mass is thoroughly united. Then water is added, and the composition boiled again till it is a perfect solution. This black or red ink is first-class and can be kept well in tightly closed glass.
Herr Andre, in Offenbach, uses an ink which has the useful property of remaining good for years in fluid form. I do not find it so good for the very finest work as those I have described, but for music and script it is excellent. It consists of:—
This is mixed with water and boiled in a clean vessel, being constantly stirred till it is dissolved. Then the boiling is continued till the water has disappeared almost entirely. Fresh water is added and the boiling continued till everything has dissolved anew. Then the mixture is filtered through a cloth and kept in a vessel where it is secure against dust. If it is seen on cooling that it is too thick it can be thinned easily with water. Also, when it dries during use it can be liquefied by adding water, unless dust has entered it.
All the above-named inks are intended for use directly on stone. If it is desired to write on paper and transfer this writing to the stone, those inks mostly prove too hard, unless one would use warmed stones, as described later. This, however, makes added work: therefore, I give here the recipe for an ink excellent for cold transfers.
The mode of preparation is exactly like that of the rest. The mass can be kept only in dried form, not mixed with water. The evidence that this ink is good for transfer work is that, after it has stood for some days, it still manifests stickiness when touched with the finger. If the ink does not transfer well to the stone under moderate pressure, it is too hard, and can be improved by mixing in a little butter or vegetable oil, but it is necessary to dissolve the whole mass again over the fire. If the design squashes under pressure, the ink is too soft. It is necessary to consider the temperature of the place where it is kept, and even the time of year, in order to produce the proper consistency of ink for the best transfer work.
Certain methods of stone-printing demand, besides the ink, a fatty, acid-resisting mass to coat the plates. It is either the same as the material used by copper-plate etchers, or, at least, is very similar to it.
Etching Ground for stone is as follows:—
Wax12partsMastic6partsAsphalt4partsResin2partsTallow1part
This is melted in an iron pan over a fire hot enough to melt the asphalt perfectly. Combustion is allowed to ensue till a third of the mixture has been consumed. When thoroughly cooled, it may be shaped in any desired form and saved for use.
A good surface is made also by common wax, boiled and burned till almost five parts of it have been consumed.
For some processes there is needed an etching ground which has the property of not coating the entire surface, permitting the etching fluid topenetrate at many spots uniformly, or, if it resists the etching fluid, still so easily affected by manipulation that it will admit the acid according to such manipulation. There are two ways to make it.
The application will be described in the instructions about aquatints, etc.
So I name a color which has the property of resisting acid when the stone is inked with it. It is useful in many cases, and even necessary. It is well, therefore, to make a supply of it.
2parts thick linseed oil varnish4parts tallow1part Venetian turpentine1part wax
All must be well melted, mixed with four parts lampblack, well rubbed down and kept in a closed tin vessel.
Chemical or fatty crayon is a composition intended to be used on the stone plate in dry form like Spanish or Parisian chalk. The inks described previously have the property of soaking into the stone and making it greasy where applied. The same happens if they are applied dry, the degree of their penetration and adherence merely being less.
The mixtures that may be used to make crayons are countless. Wax and soaps, however, are better than resinous materials. Therefore it is likely that the compositions here named will be pretty nearly the best.
The wax and soap are melted together. The lampblack is added then. All is rubbed down fine on a hot plate, and then placed on the fire again till it is fluid once more. Then it is poured on a stone plate coated with a little oil, so that it forms a cake of about one eighth inch thickness. When this has cooled a little, it is cut into thin pieces and put away till needed.
Burn the wax till one half is consumed, then melt the soap with it, and treat the mixture as before.
The first three materials are melted together, the lampblack is added, and then the whole is treated as before.
The wax is to be half burned away, then the spermaceti and soap are to be melted into it, and the whole treated as the other formulas.
The shellac is to be completely dissolved with the wax by means of combustion after which the rest of the treatment is the same as before.
The same treatment, except that the tallow is to be mixed in after the shellac has dissolved. This crayon is a little softer than the others. The same is true of the following two.
Wax, tallow, and soap are melted together and burned till one third of the mass has been consumed. Then the lampblack is added and the rest of the process is as before.
Wax, mennig, and lampblack are heated and constantly stirred till the mennig dissolves in froth and changes from red to brown. Then the lampblack is rubbed in thoroughly, the whole warmed again properly and shaped into sticks.
These are the best compositions, thoroughly tested by me, and it is very good to make a stock of all or most of them. In the case of the recipes for chemical ink, the differences are not great, and it is largely a matter of taste as to which kind one may use. But in the case of the crayons, each of them produces a different grain which creates a particular effect; so that by using various kinds of crayon one will gain greater perfection of work, or, at least, find execution easier than with only one crayon. Also, they are in proportion to the greater or lesser roughness of the stones; and the darker shadings are easier to produce with soft crayons than with hard ones, while the hard ones are best for fine shading and outlines.
The lampblack used for crayons must be burned out first, else it will develop blisters, which is the case also if the composition is poured on the plates too hot.
Crayon that contains much shellac is likely to soften in damp air; therefore it should be kept in tightly closed vessels.
The manufacture of printing-ink or color is very difficult and dangerous on a large scale. I counsel all to take lessons from a book printer when he makes it.
The varnish must be prepared in the open, far from buildings, because of its combustibility. The best utensils and skilled workmen are required, because otherwise terrible accidents may occur, and even life be lost through explosion of the copper receptacle. Whoever does not require as much as one or more hundredweight of varnish in a year, would better buy it from printers or make only a small quantity, one or two pounds, and in an open vessel. For this purpose I will describe the process.
One, or at most two pounds of good old but not rancid linseed oil are poured into a clean iron pan which has a long, strong handle and is so large that the oil takes up only one half or, better, one third of the space. This is heated over a good fire till it burns, which is facilitated by applying flame to it. Oil that is too new has much water and other impurities that make it froth and run over. In that case the oil must be poured into the pan only in small quantities, when one must take great care to avoid spattering. As soon as the oil burns, the pan is removed from the fire and placed in a safe spot. If it is hot enough, it will continue to burn. It must now be stirred from time to time with an iron rod. Usually the flame increases under this stirring, but sinks again immediately at its cessation. So long as it does this, there is no danger that the flame cannot be easily extinguished if need be. But when it begins to continue burning with a great flame after the stirring stops, and at the same time to bubble andfroth, it is high time to cover the pan with a close lid and leave it covered till the oil no longer takes fire when exposed again to the air. Then a dry knife is introduced and as much oil removed as will adhere to its point. If it does not permit itself to be pulled into long threads when cool, but is too thin, it must be heated again until it gets the required consistency.
A good varnish dries very readily of itself, and it is not only unnecessary but inadvisable to mix a drier with it, as varnish so treated is too likely to off-set on the stone.
Several strengths of printing-varnish are needed for the various methods of lithography. Therefore a stock of thin, medium, and thick varnish is needed.
In making the thin, the oil has been reduced to about two thirds through combustion. It is somewhat like fluid honey and does not pull into threads.
Only a little more than half the oil is left in the case of medium varnish. It is thick as old honey and can be pulled into threads a foot long.
In the thick varnish the mass is not much less, but it can be pulled into threads of a yard in length; and further boiling makes it thick and tough like gum elastic. In the latter case it can be used with advantage when rubbed down with oil and properly thinned. But as soon as it has obtained the last-mentioned degree of thickness and toughness, it must be cooled quickly, for then it is not far from hardening completely and becoming worthless. In the beginning it requires a long while for the oil to reach the first degree of thickness, an hour or more for a pound. But after that period the thickening progresses rapidly, so that a quarter of the time will bring it to the point of total toughness.
To make printing color of the varnish, the proper amount of lampblack must be mixed in. The roasted or burned-out is best in this also, because the ordinary lampblack delays the drying and turns yellow with time.
The more lampblack is mixed in, and the more thoroughly they are combined by rubbing down, the better will be the color. But lampblack must not be added in such quantities that the color becomes dough-like.
In describing the various styles of printing I will describe the bestprinting-inks also. I will merely make the general note here that designs on stone take the ink best when it is thin and fluid, but that there is less danger of off-set on the parts of the stone that are to remain white, if the ink is tougher or contains more lampblack.
Too much lampblack and too tough a varnish endanger the finer strokes and dots, however, so that they will not take ink, being, as lithographers say, rubbed out. The rubbing or grinding effect of too tough an ink is like that of pumice or other grinding material. With tougher varnish, clearer imprints can be made and they do not become yellow easily. But the inking is more difficult and demands greater skill, as well as heavier pressure in the press.
The varnish can be mixed not only with lampblack but with many other colors, which will be described when I reach color printing in this essay. Sometimes black lacquer is used with advantage instead of lampblack; and Frankfurter black is successful in the intaglio and aquatint methods.
It happens often that weak parts of a design cannot withstand the etching fluid and are cut away; also, that fine lines are rubbed away through unskilled treatment during printing. Then frequently a very simple remedy is to ink the plate with the so-called rubbing-up ink.
This color consists of a thin varnish in which a portion of litharge of silver or mennig or white lead has been dissolved thoroughly over the fire, and a proper amount of lampblack added. Often it is good to add some finely powdered sand or powdered pumice stone.
To prepare this, a portion of the thinnest varnish is heated in a pan till it burns. Then about an ounce of finely powdered mennig (or another lead oxide) is stirred in to each sixteen ounces of varnish till all is thoroughly mixed.
A rubbing-up ink can be made also by mixing common printer's ink with vegetable oil, tallow, and a very little soap.
Each of these colors adheres to all those places that have a trace of fat and thus gradually makes faint places in a design receptive again.
Later I will describe how to use care in applying this color, so that the entire stone shall not be smutted and spoiled.
Probably most lithographers still believe, as I did once, that the etching with acids prepares the stone, and that the succeeding application of gum merely increases this preparation. Countless experiments have taught me that the exact reverse is true. Gum arabic and a few other similar bodies are the true factors in preparation, and the acids simply make the stone more receptive for them. Only sulphuric acid, which changes the surface of the stone into gypsum, prepares it without gum; but this is available only for a few intaglio methods.
The stone used for lithography consists mostly of limestone sated with carbonic acid. Most acids, and even the salts, possess more affinity for limestone than the carbonic acid, which latter is freed and escapes in gaseous form as soon as another acid touches the stone. If aquafortis, muriatic acid, vinegar, etc., is poured on the stone, there rise a number of air blisters, which are nothing except the escaping carbonic acid, and the applied fluid seems to boil, in degree according to its strength. The boiling and bubbling last till the fluid has sated itself with lime, after which it becomes still, and is impotent for further etching.
The direct effect is the solution and destruction of parts of the surface of the stone. If it has been coated in parts with a fatty substance that resists the etching fluid, the places so coated are left untouched, so that, when the stone is cleaned, all the fat-coated lines and dots are in relief.
If the stone is coated with fatty matter, but not so thickly that the acid is entirely resisted, it will pierce the covering and eat away more or less of the stone. If the etching is continued or if the acid is strong, the fatty coat will be destroyed entirely, the surface of the stone will be clean, and ready for the ensuing preparation. The preparation of the stone for pen drawings with oil or soap-water and several aquatint methods, is based on this principle, that a very thin coating of grease can be etched away partly or wholly, at will.
After eating away the surface of the stone the acids have the property of giving it a fine polish.
Therefore if the stone has been covered with a design, and then etched with an acid, it could be inked and printed many times, as long as it is kept properly dampened and not too much pressure is used in applying the ink. However, this could be done also with a thoroughly clean stone, using only water, though the polish obtained from etching makes it much easier. But this apparent preparation is not by any means sufficient to print with certainty; and it becomes perfect only if the stone is coated with a solution of gum arabic in water after being etched. If a plate that has been merely etched and not treated with gum becomes dry during printing, or even if too much pressure be used in applying ink or in cleaning with the more or less smutty cleaning rags, it generally takes color and smut which are extremely hard to remove.
We may assume, therefore, that the acids have the following effects on the stone:—
(1) They will not attack the parts coated with grease.
(2) They will penetrate more or less if the fatty coating is only thin.
(3) Where they touch the stone they dissolve it and eat it away.
(4) They give it a polish that facilitates printing. This polish disappears after a time on account of the cleaning with sponge or rag, but is replaced by a new polish produced by this very means.
(5) They do not prevent the adherence of fatty material later, as soon as the stone is dry, for which reason the parts prepared in the beginningwith acid and gum arabic must be prepared again by renewed etching, to take the ink.
(6) Finally the acids have the property of giving to prepared stones that have been used for impressions, a rough surface instead of a polish when they are applied again, because they attack some parts more than others, producing little pores with sharp edges which catch the ink. This fact, as I will show more clearly later, makes necessary extraordinary care if one wishes to clean prepared plates or correct defects with new etching, because unskilled handling will often make them worse.
Nitric acid or aquafortis, muriatic acid, vinegar, tartaric acid, and acid of wood sorrel, all have nearly similar effects, but aquafortis and muriatic acid are used because of their greater cheapness.
Oil of vitriol or sulphuric acid, very much diluted with water, is available for light but not for extensive etching, because it transforms the surface of the stone into gypsum and deposits it again, so that after that the acid cannot penetrate at all, or only partially. If a part of vitriol, say diluted with twelve parts of water, is poured on a cleanly ground stone, there ensues a violent action which, however, is only brief. It might be supposed that the acid is sated with lime when it ceases to act, but if it is moved to another part of the stone it etches anew.
If the acid is washed from the stone and a woolen rag be used to rub it after it is dry, it takes on a mirror-like polish. In this dry condition it can be cleansed of color as easily as a copper plate, and if a stone thus polished is engraved with a steel tool, it is possible to make several impressions from it just as from copper. The polish is not lasting, however, because the skin of gypsum is very thin. But it is a useful method if it is desired to engrave the stone and ink it frequently to see the effect.
All the acids named have the property, previously mentioned, of etching the stone rough if it has been prepared before or used for impressions.It seems that the gum unites more strongly with some parts of the stone than with others, admitting the acid in these latter places. Possibly, also, the bubbles caused by etching may help to produce this roughness by hindering the uniform action of the acid. This seems to be confirmed by the fact that an etched stone, prepared with gum, does not get nearly so rough when etched again with very weak acid as it does when stronger fluid is used.
In still greater degree does this appear when using citric acid or a solution of alum in water. Take a finely ground stone, pour diluted aquafortis over it, prepare it with the gum solution, and then dry it thoroughly with a clean rag. Now pour a little citric acid or alum solution on parts of it and let it dry. Then paint the parts so treated with a fat or printing-ink. If the color is rubbed off with a wet rag, it will be seen that the stone has become white again in all places except those where the citric acid or alum are. Those parts will have taken the color exactly as if they had been painted with chemical ink. The same occurs when applying other acids, but in a lesser degree. This effect will be mentioned in future for many methods. Here I will remark only:—
It happens often that the stone takes color on places where it should remain clean. This is caused by clumsy handling, unclean rags, etc., and occurs particularly at the ends, because they dry first and are more exposed to careless manipulation. These smutted places usually can be cleansed with a clean woolen rag and gum solution or even with a wetted clean finger. But sometimes the defect will not yield so easily, especially if the printing-color is soft. Then the only remedy is to prepare the stone over again, and that is the time when one must have regard to the roughening that ensues, if the stone is not to be rendered worse instead of better.
Therefore it is best in such cases to polish the ends of the stone with pumice stone till all dirt is gone, and then to etch with diluted acid and prepare anew with gum arabic.
To be sure, it is possible to dip a clean woolen rag in strong, even pure acid, and thus etch dirt away from the ends; but great care is necessarythat no drop may touch the design, as the ink that adheres to the latter is not strong enough to resist the acid. In thus cleansing the plate, the roughening is etched away by the violent action, and a new polish is obtained.
Still, in either method of cleaning dirty places, great care must be taken not to touch roughly, press, or rub with dirty fatty rags or with dirty, fatty fingers before the gum arabic is on it. The acid eats away all the previous material used in preparation, and leaves the plate practically in its clean, natural state. Consequently it will take on grease readily, and the application of gum is essential.
It is feasible to mix the gum directly with the acid solution, but this mixture must be made fresh again each day, as otherwise it loses much of its value.
The following points are important:—
First: If the grease remain long on a stone that, though prepared, has lost its coating of gum, it will penetrate the surface, and according to its amount and fluidity, will sink more or less into the stone, which will retain its polish on the surface but become more inclined to take dirt. It is better, therefore, to leave a small amount of gum coating on the stone in such cases.
Second: As only the extreme outer surface of the stone is prepared by the gum, and this is rubbed away gradually by wiping during the printing, so in the same proportion of wear and tear the original preparation would become lost, if it were not renewed from time to time, that is, if the stone were not again coated with gum. Twice a day, however, is enough.
Third: Because of this susceptibility of the surface to injury, a prepared stone must not be rubbed strongly with fatty material, because this damages the surface and the stone would readily soak up the fat.
Fourth: If a prepared plate is totally denuded of gum, and has been dry for a time, especially if it has already lost a part of the preparation through printing, it will incline very much to take color and smut. Therefore, when it is necessary to stop printing, it is well to coat the plate at once with gum, but only with a very thin coat. If this has notbeen done, and it is desired to use the plate again, great care must be taken to wet it with the very purest water, or, better still, with diluted etching fluid, for instance one part aquafortis to five hundred parts of water; and then to coat it with gum. To neglect this precaution may cause the total ruin of the plate. For safe-keeping of the plates, if they are to be used again for printing, the coating with gum is, therefore, absolutely necessary.
Fifth: Gum can prepare only a thoroughly clean stone or one properly etched. Therefore, if the surface of the stone has even the least trace of grease, it will take color, no matter how thickly it may be coated with gum. On this fact is based the method of transferring copper-plate impressions and other printed subjects, as will be described later.
Sixth: If the stone has had fat on its surface, and this fat has been etched away again, the power of the gum asserts itself, and the stone will be thoroughly prepared even if the fat has soaked considerably into the body of the stone.
Seventh: Mere grinding of the stone is not sufficient to attain a complete preparation through gum alone. Therefore, if an otherwise clean stone has some places after grinding where the fat has soaked in deeply, and one coats it with gum, the stone will take color after a time on these fatty places, as soon as the inked rag has been rubbed over the stone many times. However, this taking-on of color is only slight if the gum solution is thick, and long-continued cleaning will transform it into complete preparation.
Eighth: From both preceding observations we learn:—
Printing forces the color to sink considerably into the stone. If such a stone is required for new designs, it is not practicable to grind it so much that all the fatty places can be ground away. Therefore it is ground only till it is thoroughly even again. Then it must be well etched; otherwise it may happen that in printing the surface will rub away and the entire previous writing or design will appear again, a trouble hardly to be remedied.
If the stone is dirty in the middle, it can be cleaned in many cases bypouring on a few drops of oil of turpentine and the same quantity of gum solution, and rubbing it clean with a woolen rag. Then it must be washed with a wet sponge, after which it is inked. If it has not lost the smut, the only remedy is new preparation. As this must be done differently for each different lithographic style, it will be described in its place.
If fat has soaked well into the stone in places where it is not desired, it is always very difficult to remove it without injuring adjoining parts. Correction of crayon work, if it has been etched and used for printing, is especially difficult. It is true that the defective parts can be cut out easily with a sharp instrument, but then these places must be prepared again. If weak etching fluid is used, it will not suffice. If strong fluid is used, the fine parts are easily attacked, and at the same time the surface will become roughened so that the stone often blackens entirely in the corrected parts. To avoid this trouble, and to facilitate corrections, I made many experiments to discover an acid composition that should prepare a stone anew and perfectly and yet not roughen the surface. I found the best material in phosphoric acid, especially when mixed with finely crushed nutgall.
Water in which phosphorus has been kept a long time becomes acid and etches the stone. The acid can be obtained more quickly by burning the phosphorus and catching the smoke. This method is somewhat expensive, but one does not need much, as it is used only for correcting defects.
If a few drops of aquafortis or other acid are poured on a clean ground stone, it will be etched. Now wipe the etching fluid off clean and coat the plate with soap-water or chemical ink. As soon as it is dry, clean it of the fatty coating with a few drops of oil of turpentine. If it is dampened then with water and inked, it will take color everywhere, even at the etched places. If gum is mixed with the acid, the same result occurs, though the stone has been thoroughly prepared where this mixture touched it. From this it appears that soap-water (and the alkalis in general) can destroy the preparation given to the stone and make it receptive again to fats.It is different if phosphoric acid is used. This makes a preparation that can be destroyed only by very frequent coating of soapy water.
Still more durable and resistant to soap is the preparation if fine nutgall is mixed with the phosphoric acid and water solution. Nutgall gives even the other acids the property of resisting soap more than ordinarily. The study of this effect led me to invent the method of transforming a relief design into intaglio. Also, it is only by the use of phosphoric acid that one can do thoroughly that style of lithographic work which resembles the scraped style in copper, or the so-called black art.
If a cleanly polished plate is sprinkled with a few drops of gum arabic dissolved in water, the sprinkled places will take no color so long as they are wet. When they dry, color will adhere, but can be washed away easily with a wet sponge. This shows that the gum alone will prepare the stone. The preparation will become more durable, however, if the stone is etched first.
In both cases, however, the preparation extends only over the outermost surface of the stone, penetrating only slightly, so that the least injury will make it take color as soon as it is dry. On this fact is founded the intaglio style of lithography. Therefore, if a clean ground stone is etched, then prepared with gum and dried clean, it can be coated with printing-ink or other fat substance (excepting soap and all alkaline compositions), and there will be no danger that it will lose its preparation. The thicker the gum coating, the less can the fat penetrate.
In printing, during which the stone must be kept wet, only the original coating of gum is necessary; but as the surface thus prepared soon diminishes under the frequent wiping, it is necessary in some forms of work to mix gum with the printing-color or with the water used to dampen the stone. More of this will be explained in the proper place.
Here I will add only that the domestic gum of cherry and plum treesis good for preparing stones some years and worthless in others, when it cannot be dissolved in water. In possessing the properties for preparing stone, the juice of many plants and fruits, sugar, and most mucous materials of the vegetable and animal kingdom, such as white of egg, approach gum arabic more or less. The latter, however, is to be preferred because of its reliability.
Here I impart my experiences in regard to an astonishing phenomenon that occurs often in lithography and gives much trouble, especially to beginners. It is the so-called imperfect or semi-preparation, wherein the stone betrays a strong inclination to take color, and still will not do it or will do it only partially.
(a) If a cleanly ground stone is marked with chemical ink, etched, and prepared, the marked places will take the printing-color and produce impressions. If, after the stone is inked, one rubs strongly with the wetted finger, the color can be wiped from the design, especially if it has not been on the stone long and has been standing in a damp place. A place whence the color thus has been removed does not take it readily when the inking-roller is applied again; and the reluctance is the greater in proportion to the length and violence of the rubbing and the toughness of the printing-color. The stone shows clearly the traces of the penetrating fat; indeed, if the stone is rubbed with a wet linen rag that is inky from previous use, the design will reappear in black. But as soon as the roller is used, instead of inking these places, it takes the color off; and whatever means may be tried to make the defective places receptive again to color, it remains difficult, often impossible.
What has happened is that the wet rubbing has cleansed the surface of the stone of all its fat and at the same time has polished it and made it slippery. It is a sort of preparation; and though the fat of the ink has penetrated into the interior of the stone, the accidental preparation stilloffers an obstacle which prevents the printing-ink from adhering to the fat in those places. As I will show, these places can be prepared again thoroughly.
(b) Another case is when the design is too weak, and has been attacked by the etching-fluid too powerfully, though without being destroyed. Here the printing-color usually is removed by the ink-roller, even though it adheres pretty well when being wiped.
(c) A third kind of imperfect preparation is when a stone inclines to take color or smut on prepared places. This happens sometimes in part, sometimes over the whole surface, which latter effect is described by saying that the stone has acquired a tone.
The cause of this phenomenon may be one of many. It is either due to the appearance of a fat that has been in the stone, or to the fact that unskilled manipulation has destroyed the preparation partially.
Thence follow several observations again:—
(1) Mere wiping with clean water will give the stone a sort of preparation if the material used for wiping is suitable. This preparation is incomplete, but can be transformed very easily into a complete one. This incomplete preparation is according to the strength with which the rubbing material affects the stone. Linen and cotton stuffs have the least effect. More potent are animal wools and hair, silk or wet leather. The printing-color itself has a preparing property if it is made of very tough varnish or contains much lampblack. This effect is increased if Frankfurter black or powdered charcoal is mixed with the color, and the stone is kept very wet.
(2) The partial preparation is produced more quickly and made more durable if the water contains gum or gummy stuffs.
(3) The operation is still quicker if a weak etching fluid is used. A stronger fluid would make the preparation a complete one, but would also injure the good spots. Then again one must remember that the second etching produces the roughness discussed already.
(4) Grinding with sand, pumice, and other grinding materials also produces partial preparation, which is transformed easily into completepreparation by applying gum. Here, however, the circumstance is noteworthy that a plate that has been blemished by rubbing can be made to do the reverse, namely, to take color, by means of light grinding with water. Assume, for instance, that a plate designed and prepared in relief style has been spoiled by handling so that the design refuses to take color. It is necessary merely to rub it all over with water and fine sand or to clean it with oil of turpentine so that all printing-color is removed from the surface. Then place it in a receptacle containing a great deal of very clean water. If it is ground delicately then with a very clean pumice stone, without destroying the traces of the fatty material that has soaked in, it can be brought to take color again as well as ever. Take a little of the before-mentioned acid-proof ink, smear it on the color-stone, and apply a clean linen or cotton rag. Wipe the stone that is lying in the water very gently with this rag, and the color will fix itself bit by bit on all parts of the design, even if the entire relief produced by the etching should have been ground away. It is necessary only that the fat shall have soaked in sufficiently; and this usually is produced soon enough by the printing. After the plate has accepted color completely, it is to be completely prepared by light etching and with gum, and then it will take the color properly from the ink-roller.
If this experiment is to succeed, it is to be noted that in grinding there must be no trace of fat on the stone or the pumice, because the rubbing during grinding might transfer this greasiness to those parts of the stone that are to remain white. Care must be taken, also, not to press too hard in applying the etching color, because the places that have been cleansed of all gum by the water, and thus are inclined to accept color, will smut easily. Finally, the stone must not be permitted to dry before it is fully prepared again by etching and gum coating, for it might easily become entirely smutted and useless.
This experiment leads to the conclusion, which has been proved correct in many ways, that a soft rubbing in clean water with printing-color, especially if it contains tallow, is very well adapted for transforming the incomplete preparation into a condition of accepting fat perfectly, and ofgiving injured places new potency. Also, that the contrary effect can be produced by violent rubbing, especially with wool, leather, or tough colors, because this prepares the wet stone and makes it useless for accepting fat. The first method may be used with advantage, therefore, for reëstablishing a vanished design. The second method is good for getting rid of smut. If the smut has occurred in previously clean and thoroughly prepared places, it can be destroyed entirely. But if it is only that the deeper fat has lost its superficial polish, and has appeared again, the stone will be only partially prepared by this last method and must be newly prepared on the desired places with weak etching-fluid and gum, for durability's sake. It is easy to see how important this circumstance is. With the one and the same process in various degrees of manipulation, opposite results can be produced; and I may declare that only he is to be termed a perfect lithographer who has exact knowledge of this especial matter.
(5) It has been mentioned already that every sort of preparation can be destroyed by a renewed etching, and particularly with alum and citric acid. The same is caused by soap and alkaline compositions; therefore also by chemical ink if it contains a sufficient amount of alkali.
(6) Simply letting the stone plate rest produces important, often contradictory, phenomena. If smeared parts refuse color, clean water poured over these places runs from them as quickly as it does from the fatty parts. This is the surest sign that they still have fat, though it is not sufficient to attract the color. If such a stone is permitted to lie idle a few days, even if coated with gum, it will often take the color thereafter. On the contrary, if a stone plate has taken on color at the well-prepared places (usually readily removable by wiping with oil of turpentine and gum solution, but generally reappearing), it need merely be inked after such cleansing, coated with gum and left idle, and in a few days it loses the readiness to take dirt.
The cause of both phenomena is that in the first case the fats that lie deep gradually work upward into the partly prepared surface and practically reëstablish their interrupted communication with the printing-color.In the second case, the small quantity of fat that has adhered merely to the surface has penetrated into the stone, so that it loses its effectiveness. Added to this, in the latter case, is the fact that the linseed oil, and the varnish prepared from it, acquire the property of losing their fats when they are dried in the air, and thus will take color poorly or not at all. This observation led to the invention of an artificial stone or stone-paper.
(7) In contrast with preparation by wet wiping there is the wiping with dry and fatty bodies, which produces full acceptance of color on the partially prepared plate, while in the case of the fully prepared plate there occurs at least partial color acceptance or semi-preparation. As every property of the stone can be used for good impressions just as well as it serves in unskilled hands to ruin a design, so in this case; the lost parts can be restored through proper use of rubbing with a dry, fatty substance, and the clean, prepared portions of the plate can be smutted. There will be more about this.
As the entire art of stone-printing depends on proper preparation, it will not be out of place to express my views as to the nature of the process. This will serve also as recapitulation.
(1) Limestone has countless little pores. These can soak up fatty as well as watery substances.
(2) These can adhere easily to the limestone particles, but are easily separated again, as long as the nature of the stone is not altered. This alteration is produced most readily by sulphuric acid, tartaric acid and phosphoric acid.
(3) Water evaporates from the pores as the stone dries. Gum and other slimy substances do not.
(4) Fats soak into the stone more and more. There is no means of destroying them except to remove the limestone itself by grinding or etching.
(5) Printing-color cannot adhere to the stone so long as a proper amount of moisture forms a wall between it and the stone. Under any circumstances it adheres only poorly to the lime particles, and assumes great power of adherence only when the pores of the stone are filled with fat, which are pinched in them, so to speak, and with which the printing-color strives to unite because of mutual affinity.
(6) This stronger adherence (or complete color reception) thus happens only when the outer color can reach and touch the inner fat. If the latter is deep in the stone, so that the communication is broken, it becomes difficult and the communication must be restored.
(7) This interruption occurs either if the color is rubbed away by force and with help of moisture, or if a substance that closes the pores unites with the stone.
(8) The rougher, sharper, and more angular the pores are, the more readily does the color find adhering points. It adheres at first to the surface by virtue of merely mechanical conditions. But when the moisture which hinders a complete union and greater penetration has dried, the color begins to penetrate deeper into the stone and to fill its pores. The most color will always adhere to rough spots. Therefore, it happens often, in some styles of work, that a stone too highly polished will seem perfectly black when inked, and still fail to yield a strong impression. For the same reason the impressions from soft stones usually are the stronger, especially if the mode of printing demands the use of thin printing-color.
(9) The effect of the etching fluid is in part a greater polishing of the surface, in part a filling of pores. Both make the stone reluctant to take color.
(10) If the stone has been prepared and polished already, it can be made rough again and receptive to color by being reëtched. At the same time the prepared surface can be destroyed by etching, and a communication established with the fat lying in the interior. The result is according to the manipulation.
So much in general. In describing the various styles I will make everything clearer.
In lithography there is use for many various tools and utensils. I will mention here merely those that are made primarily and exclusively for the art.
One of the most necessary tools of lithography is the steel pen for writing and drawing on the stone. Simple as its manufacture is in principle, it demands much care and skill. The beauty of the work depends largely on a good and well-cut pen. The best artist, using the best chemical ink on a perfectly prepared plate, cannot do good work unless the pen is good and cut to suit his hand. Therefore it is necessary to learn how to make these pens, because, apart from their costliness, it is difficult to get a suitable one from a worker in steel. The ordinary steel pens that can be bought ready-made from stationers are fairly available for coarser writing and drawing; but for better work one must have much finer pens.
Following is the way to make them:—
Take the spring of a pocket watch, not too small nor too broad; one and a half to two lines in breadth is best. Clean off all fat by polishing with sand or chalk. Lay it in a glass or porcelain vessel, and cover it with a solution of aquafortis and water in equal parts. Let the acid etch the steel till it has lost about three fourths of its thickness, and has become as pliable as a similar strip of letter-paper. From time to time the steel must be removed from the fluid and dried with tissue paper. This produces uniformity of etching. The steel rarely is quite uniform, and it has happened to me often that it is attacked unequally and that holes are eaten into it before it has been etched away sufficiently. That this, however,is due mainly to the quality of the acid, I learned because I found that the same steel would be attacked clean and uniformly as soon as I obtained aquafortis from some other source.
A pen is poorly etched if it has many elevated points or pits and holes. The former appears to result from insufficient cleansing, the latter is due to the quality of the acid.
Oil of vitriol diluted with water, or nitric acid can be used.
Those who have a very light touch may etch their pens to great thinness, and will be enabled to do very delicate work. For a heavy touch they must be firmer, otherwise fine strokes will look shaky.
When the steel is thin enough, it is removed and cleansed with fine sand that it may not become rusty in future. Then it is cut into pieces two inches long with good English shears. Now these must be shaped half-round. To do this, lay them on a flat stone and beat them lengthwise till they bend, using a small watchmaker's hammer, whose faces are pretty thin but well rounded. Two or three sheets of paper laid under the steel facilitate the work.
Another way to give it the half-round form is to file a groove into a stone, giving it the exact shape the pen is to have. Into this groove lay the piece of steel, put in a drop of vegetable oil, and polish with a steel instrument whose end resembles a broken but well-rounded nail. Use sufficient pressure, and the steel will gradually assume the desired shape.
Either of these methods may be used, according to preference. It is to be noted that the degree of roundness depends on the artist's need, one finding a well-rounded pen better, another preferring one not so well-rounded. The less the pen is rounded, the more it will resemble a brush when used, but the points will not spread so well without considerable pressure. The more they are hollowed, the stiffer are the pens and the more easily will the points spread when pressed.
After the pen is curved, it must be cut. With small, well-sharpened scissors cut a slit about one line in length into one end. Then cut away from the two sides as much as necessary till the point is sufficiently fine. Do not cut away too much at once, as the pen bends easily and then mustbe straightened out again, which demands especial skill. It is well to do the cutting from the point toward the sides.
A good pen must have both points very uniform, so that they touch perfectly and lie on the stone evenly in the position given them by the hand when working. The cutting alone will do this, but a small, very fine whetstone may be used to aid.
A newly cut pen is somewhat rough at times and cuts into the stone, thus gathering powder that hinders the work. This defect generally cures itself after a few strokes on the stone. Beginners generally spoil their pens by bending them every few moments. Then they must be straightened out, which demands practice and judgment. It cannot be described, because the bending may assume a thousand shapes. It may be mentioned, however, that the points must always touch, but must under no circumstances interfere, one being forced behind the other. It is good, sometimes, if one can see through the slit when looking backward from the point. Some even cut a tiny bit out of the middle for this purpose, but that demands great skill and extremely good scissors, as otherwise the opening will be too large, which will spoil the pen entirely.
The ordinary drawing-pens, which can be loosened or tightened with screws, can be used very readily for drawing lines, if their points are made from very good steel that can be ground very fine and thin. However, for much line-work, for instance the background of a picture which consists of lines hatched crosswise, it is better to use the other pens. The ordinary drawing-pens are too likely to catch a little dust or dirt between their points, and then will spoil the lines.
Of all work of the pen style in lithography, the most difficult is to draw very fine and even lines with a ruler. I have succeeded best by using a pen previously so cut or ground that both points touched in the position in which I was accustomed to hold the pen when guiding it with the ruler. It is evident that the pen must be held to the ruler on its side, so that the groove that contains the ink does not point in the direction of the ruler, but away from it. It is well if there is a tiny space in the slit, as it helps the free supply of ink.
Brushes are used for various purposes, as to prepare the plates, cleanse, etch, etc. Here, however, we speak chiefly of the small brushes required for writing and designing. For this are used the very smallest and best miniature brushes, and they must be especially treated.
If it is desired that the brush make thicker strokes under pressure, the ordinary condition of it, in which all the bristles come to a point, is quite sufficient. But it is very difficult to lay on strokes of uniform thickness with them. Press the brush on the table, spread the bristles fanwise with a knife and cut away from each side about a half-line deep. Turn the pencil to the other side, stroke it again to spread it, and cut the same amount as before from each side. Continue this till there remain only ten or twelve bristles of the original length in the brush. Then cut these even at the ends. These should not be altogether the middle ones if the pencil is to be first-class. Neither should they be too far apart. They should hang together well when the brush is dipped into the ink, but not so closely that they will not let the ink pass well. With a brush successfully trimmed thus, the handsomest drawings, resembling copper plate, can be done with ease.
For coarser strokes, coarser brushes are needed. More bristles are permitted to remain in them.
These serve for the intaglio process, to draw into the stone, and must be of the best and hardest steel. In Munich there are also used the little five-angled watchmakers' borers, which are glued between two pieces of wood planed round in form of a pencil and so cut at the end that only a bit of the tool is visible. In using very thin needles one has the advantage that they are ground and sharpened easily.
For coarser strokes, coarser needles are needed. For fine strokes,especially if they are to go in all directions, the needles are best ground perfectly round.
To transfer drawings very accurately and reversed on the stone, which is necessary especially in the case of charts and plans, a pantograph is used in Munich, which is so arranged that the stone is upside down and elevated. The inscribing-needle is just opposite the one that is managed by the hand, and when one follows the lines of the original exactly, there results a perfect but reversed copy on the stone. Such drawing-machines can be obtained from Herr Liebherr and Company in Munich. This skilled mechanician also makes a sort of pantograph of his own invention, with which drawings can be transferred to stone, reversed or otherwise, and in any desired proportion. Pictures of such machines may be obtained from him.
These are: a grinding-table, an etching-trough, some rulers, a writing-table, some music-writing pens and rastrums for those who wish to print music, small brush for spatter-work, a wiping-machine for the wiping method, several rollers and balls for inking, and some presses for wetting and pressing the paper.
Any firm table may be used for grinding, but it is better to have one made heavy enough to resist the strain of the powerful friction, and so made that the stones can be fastened on it readily. If this work is done in a room, it must have a depression in the middle and a hole, that the water may run off into a receptacle. Along the sides should be a low rim, that the sand and dust may not drip all over the floor.
The etching-trough is a square, well-pitched box whose bottom is depressed toward the middle, that the etching fluid may gather there and run through a hole into a receptacle, so that it can be poured over thestone again. The trough must be large enough to accommodate the stones easily. These must not, however, touch the bottom, but must rest on little pieces of wood or cross-pieces.
Besides the ordinary rulers, a large, broad one is required, about three to four feet long, five inches wide, and so shaped that on one side it is one-half inch thick, on the other only two lines thick. On this latter side a strip of pear wood must be glued and very truly planed off. Thus it can be used for drawing lines, although the real purpose of this ruler is only for supporting the hands when working on stone, that they may not touch the prepared surface.
If the work-table is made with high pieces at the ends so that the ruler can rest on them without touching the stone, no ruler supports are required. Otherwise one must have these two pieces, a little higher than the stone, so that the ruler may rest on them.
A specially made work-table has another advantage. In the middle there can be a turntable on which the stone rests, so that it can be moved easily into any position, something that is very difficult with large stones without this arrangement.
Music-writing pens are brass or silver tubes which have the shape of musical notes underneath, and which take up such a quantity of chemical ink that one can make about twenty notes without re-dipping. That they shall not take up too much ink, a fine wire is fastened in the centre. These instruments must be very exactly ground and their use demands some skill if the notes are to be uniform.
Instead of this instrument a piece of wood may be used, but this must be inked anew for each note. To avoid dipping too deep, it is best to spread some ink on a little stone and ink the instrument from this. It must be wetted in the beginning, that the ink may be sucked up about three lines high. After that the ink on the stone need merely be touched with it, and this makes the work very uniform. Beginners find this easy to use. But one works more swiftly with the other.
Of the rastrums, there is nothing to say except that they are of steel and very even at the ends so that they touch the stone in all places. Theyserve to draw the five lines for music. For making the broad strokes for notes, one can use coarse drawing-pens, or coarsely cut steel pens; but the best are those adjustable drawing-pens that are made from three blades.
The brush for spatter-work, the wiping-machine, and the dauber will be described in the description of the styles of work for which they are used.
Ink-rollers and balls are for laying on the printing-color. The latter are made from soft leather, stuffed with horsehair, like the ordinary book-printer's balls. The former are wooden cylinders with thin handles, of any requisite length and about four to five inches thick. They are wound with two or three thicknesses of woolen cloth and then covered very firmly and evenly with leather. Usually there is used sheep's leather from which the grease has not been entirely removed. Calfskin, worked white, is good and more durable. Dogskin is considered best. Some printers use soft red calfskin, turning the inner side out. The leather must not be stitched with linen but with silk thread, because linen does not take the ink as well as leather and silk do. The leather must be dampened when being drawn over the cylinder.
A fair stock of these rollers is required, because they are liable to become water-soaked during use, when they lose much elasticity and fail to give good service, so that dry ones must be on hand.
It is not well to have movable handles on the rollers, because then they are likely to roll over the stone too lightly and it is not within one's power to lay on the ink thoroughly. To prevent blistering the hands, thick leather covers may be used. Then it is possible to use any desired pressure.
Paper presses are needed both to obtain a uniform dampening of the paper as also to restore the proper flatness to the printed paper. Models are to be seen at the shops of all book-printers and binders.