First, with a tracing-brush, go over all the lines and outlined shadows that seem too weak, and then, when these touches are quite dry, pass a thin matt over the
whole, and with stippling-brushes of various sizes, stipple it nearly all away while wet. You will only have about five minutes in which to deal with any one piece of glass in this way, and in the case of a head, for example, it needs a skilful hand to complete it in that short space of time. The best plan is to make several "shots" at it; if you do not hit the mark the first time, you may the second or the third. I said "stipple it nearly all away"; but the amount left must be a matter of taste; nevertheless, you must note that if you do not remove enough to make the work look "silvery," it is in danger of looking "muddy." All the ordinary resources of the painter's art may be brought in here: retouching into the half-dry second matt, dabbing with the finger—in short, all that might be done if the thing were a water-colour or an oil-painting; but it is quite useless to attempt to describe these deftnesses of hand in words: you may use any and every method of modifying the light and shade that occurs to you.
[CHAPTER IX]
Of Staining and Aciding—Yellow Stain—Aciding—Caution required in Use—Remedy for Burning—Uses of Aciding—Other Resources of Stained-Glass Work.
Yellow stain, or silver stain as some call it, is made in various ways from silver—chloride, sulphate, and nitrate, I understand, are all used. The stain is laid on exactly like the pigment, but at the back of the glass. It does not work very smoothly, and some painters like to mix it with Venice turpentine instead of water to get rid of this defect; whichever you use, keep a separate set of tools and a separate palette for it, and always keep them clean and the stain fresh mixed. Also you should not fire it with so strong a heat, and therefore, of course, you should never fire pigment and stain in the same batch in the kiln; otherwise the stain will probably go much hotter in colour than you wish, or will get muddy, or will "metal" as painters call it—that is, get a horny, burnt-sienna look instead of a clear yellow.
How to Etch the Flash off a Flashed Glass with Acid.—There is only one more process, having to do with painting, which I shall describe, and that is "aciding." By this process you can etch the flash off the flashed glasses where you like. The process is the same as etching—you "stop-out" the parts that you wish to remain, just as in etching; but instead of putting the stopping material over the whole bit of glass and then scratching it off, as you do in copper-plate etching, it is better for the most part to paint the stopping on where you want it, and this is conveniently done with Brunswick black, thinned down with turpentine; if you add a little red lead to it, it does no harm. You then treat it to a bath of fluoric acid diluted with water and placed in a leaden pan; or, if it is only a touch you want, you can get it off with a mop of cotton-wool on a stick, dipped in the undiluted acid; but be careful of the fumes, for they are very acrid and disagreeable to the eyes and nose; take care also not to get the acid on your finger-ends or nails, especially into cuts or sore places. For protection, india-rubber finger-stalls for finger and thumb are very good, and you can get these at any shop
where photographic materials are sold. If you do get any of the acid on to your hands or into a cut, wash them with diluted carbonate of soda or diluted ammonia. The acid must be kept in a gutta-percha bottle.
When the aciding is done, as far as you want it, the glass must be thoroughly rinsed in several waters; do not leave any acid remaining, or it will continue to act upon the glass. You must also be careful not to use this process in the neighbourhood of any painted work, or, in short, in the neighbourhood of any glass that is of consequence, the fumes from the acid acting very strongly and very rapidly. This process, of course, may be used in many ways: you can, by it, acid out a diaper pattern, red upon white, white upon red; and blue may be treated in the same fashion; the white lights upon steel armour, for instance, may be obtained in this way with very telling effect, getting indeed the beautiful combination of steely blue with warm brown which we admire so in Burne-Jones cartoons; for the brown of the pigment will not show warm on the blue, but will do so directly it passes on to the white of the acided