By the combination of these two processes three tints may be obtained, or even four upon the same piece of gla.s.s--say white, green, and yellow all upon a blue ground.

There is a third method of avoiding lead glazing. If little jewels of coloured gla.s.s be cut out of various sheets and placed upon white gla.s.s they become fused at a sufficient heat in the kiln, and adhere more or less firmly to the gla.s.s on which they are laid; but this process of "annealing" is not very safe. Still less to be depended upon is the fourth process of "enamelling." In that case the coloured gla.s.s is applied in the form of a paint upon a sheet of white. Fusing at a comparatively low temperature, it rarely gets quite firmly fixed. Nor has it the depth of pot-metal colour. The three processes of staining, annealing, and enamelling, entail, it will be seen, the burning of the gla.s.s. Literally this is the limit of what can be done in stained gla.s.s.

[Ill.u.s.tration: 54. WINDOW IN WHITE AND STAIN, WARWICK CASTLE.]

The term stained gla.s.s, however, is generally used to include painting, which from the first has been a.s.sociated with it. This painting (not to be confounded with the above mentioned enamelling) is a second process, which the gla.s.s undergoes after it is cut and before it is fired. It is not in the least what a painter understands by painting. It is, in the first place, a means of giving in solid brown pigment, which effectually stops out the light, detail smaller than mere glazing would permit, such as the features of a face or the veining of a leaf: it gives the foils of the foliage, and marks the individual berries in the border overleaf.

In the next it is used partially to obscure the gla.s.s, so as to give shading. The pigment is not used as colour, but for drawing and shading only. Local colour is represented by the pieces of pot-metal gla.s.s employed; the painting fulfils precisely the part of the engraving in a print coloured by hand. The various methods of painting are explained on pages 45, 64, 89. In some respects they have more affinity with line drawing, mezzotint, and etching than with oil or water-colour painting.

[Ill.u.s.tration: 55. AUXERRE.]

It is extremely difficult to get delicacy of modelling or high finish at one painting--to all but a consummate gla.s.s painter impossible. Many a time the work has to be painted several times over, each painting being separately burnt in, always at some risk. Painting that is not sufficiently fired peels off in time. If it is fired too much it may be burnt quite away.

The effect of paint in the form of shading is naturally to obscure the gla.s.s. Up to a certain point there is not much harm in that; it counts for nothing as compared with the facilities of expression it affords.

But that point is soon reached. Then it becomes a question of the relative value of, on the one hand, purity and translucency of gla.s.s colour, and, on the other, of pictorial qualities. The problem is to get the utmost of modelling or expression with the minimum of obscuration.

Much depends upon the method of painting adopted. So long as the light is allowed to get through it, one may indulge in a fair amount of shading, but a deep even tint, leaving none of the gla.s.s clear, is inevitably heavy. The more one can represent shadows by deeper tinted gla.s.s the more brilliant the result will be.

This painting, although, strictly speaking, in brown enamel, is not, as was said, what is usually meant by enamel painting: that is described on page 77. A window may be painted altogether in enamel; and, when the mosaic method went out, designs were painted in enamel upon panes of plain white gla.s.s; but, for the most part, since the pieces had to be connected by lead, it was found convenient to use pot-metal for some of the stronger colours. In recent times, however, owing to the introduction of large sheets of thicker gla.s.s, to improved gla.s.s kilns, and also to more accurate knowledge of the chemistry of enamel colours, it is possible to paint a picture-window on one sheet of gla.s.s. That has been done with extraordinary skill at Sevres. You may see really marvellous results in this kind in the Chapel of the Bourbons at Dreux.

If you want neither more nor less than a picture upon gla.s.s, and are content with a picture in which the shadows are opaque and the lights transparent, that is the way to get it. You will not get the qualities of gla.s.s. Within the last two or three years there seems to have been very considerable improvement in the purity, translucency, and depth of enamel colours. How far they are lasting remains to be proved. Anyway, brilliant as they are, they have not by any means the intensity of pot-metal gla.s.s, and it does not seem, humanly speaking, possible that a film of coloured gla.s.s upon a sheet of white can ever compete in strength and volume with colour in the body of the gla.s.s itself.

If, therefore, we want the qualities of deep, rich, luminous and translucent colour, which gla.s.s better than any other medium can give, we must resort to the use of pot-metal--that is to say, to glazing--a.s.sisted more or less by brown paint, used, not to get colour, but to stop it out, or to tone it down.

According to the more or less of your dependence upon paint your method may be described as mosaic or pictorial.

Starting upon the mosaic system, you rough out your design in coloured gla.s.s (or what stands for it upon paper), and then consider how, by use of paint, as above mentioned, you may get further detail, shading, harmony of tone.

Starting upon the pictorial system you sketch in your design, shade it, and colour it, and then bethink you how you can get the gla.s.s to take those lines.

In either case you have, of course, from the first, a very distinct idea as to the a.s.sistance you will get from the supplementary process; but it makes all the difference whether you think first of the gla.s.s or of the painting. Upon that will depend the character of your window. If you want all that gla.s.s can give in the way of colour, begin with the mosaic. If you want pictorial effect, think first of your painting. If you want to get both, balance the two considerations equally in your mind from the first. Only, to do that, you must be a master of your trade.

A first consideration in the design of a window are the bars which are to support it. The skilled designer begins by setting these out upon his paper, nearer or closer together, according to the width of the opening, from nine to eighteen inches asunder. In a wide window it may be as well to make every second or third bar extra strong. Upright stanchions may also be introduced. Exigencies of design may make it necessary to alter the arrangement of bars with which you set out. You may have occasionally to bend one of them to escape a face, or other important feature; but, if you begin with them, this will not often be necessary.

Bars may be shaped to follow the lines of the design. There is nothing against that, except that it is rather costly to do; and, on the whole, it is hardly worth doing. In big windows, such as those at King's College, Cambridge, raised some feet above the level of the eye, stout bars have, in effect, only about the value of strong lead lines, whilst lead lines disappear.

The points to be observed with regard to glazing are these: Since leads must form lines, it is as well to throw them as much as possible into outlines. In a cleverly glazed window the design will tell even when the paint has perished. To glaze a picture in squares, regardless of the drawing, is mere brutality. Because by aid of the diamond gla.s.s may actually be cut to almost any shape, it is not advisable, therefore, to design shapes awkward to cut, but rather to design the lead lines of a window with a view to simplicity of cutting and strength of glazing.

Pieces of gla.s.s difficult to cut are the first to break. It is the business of the designer to antic.i.p.ate breakage by introducing a lead just where it would occur. _Tours de force_ in glazing are not worth doing. It is a mistake to be afraid of leads. Skilfully introduced, they help the effect; and, except in work which comes very near the eye, they are lost in the gla.s.s.

The quality of pot-metal gla.s.s is all important. It should never be mechanically =flat= and even. The mechanically imperfect material made in the Middle Ages is so infinitely superior to the perfect manufacture of our day, that we have had deliberately to aim at the accidents of colour and surface which followed naturally from the ruder appliances and less accurate science of those days. There are legends about lost secrets of gla.s.s making, to which much modern produce gives an appearance of truth.

But, as a matter of fact, though old gla.s.s undoubtedly owes something of its charm to weathering, better and more beautiful gla.s.s was never made than is now produced; but it is not of the cheapest, and it wants choosing.

The choice of gla.s.s is a very serious matter. What are called "spoilt"

sheets are invaluable. It takes an artist to pick the pieces. But without experience in gla.s.s the judgment even of a colourist will often be at fault. Some colours spread unduly, so that the effect of the juxtaposition of any two is not by any means the same as it would be in painting. It is only by practical experiment that a man learns, for example, how much red will, in conjunction with blue, run into purple, and which shade of either colour best holds its own. Effects of this kind have been more or less scientifically explained--by M. Viollet le Duc for one--but, in order to profit by any such explanation, a man must have experience also.

Referring to "flashed" gla.s.s, all kinds of double-gla.s.s are now made: red and blue = purple, yellow and blue = green, and so on; but there is not, except, perhaps, in work on quite a small scale, much to be gained by this. In fact, it is not well in work on a fairly large scale to depend too much upon etching pattern out of coated gla.s.s. In a window breadth of effect is of more account than minuteness of detail. Damask or other patterns in draperies might, more often than they are, be leaded up in pot-metal. It would compel simplicity on the part of the designer, and the effect of the gla.s.s would be richer.

With the increasing variety of coloured gla.s.s now made, plating becomes less necessary than once it was. The drawback to the practice is that dust and dirt may insinuate themselves between the two pieces of gla.s.s, and deaden the colour. The safe plan is to fuse the two pieces of gla.s.s together.

Good gla.s.s is more than half the battle. Raw gla.s.s may be toned down by paint, but poor gla.s.s cannot be made rich by it. The Italian gla.s.s painters often used crude greens and purples, and softened them with brown. They might do that with comparative safety under an Italian sky; but the deeper tones produced that way have not the purity and lusciousness of juicy pot-metal, and the paint is liable to peel off and betray the poverty of the cheap material. It is the fundamental mistake of the painter, because by means of paint he can do so much, to depend upon it for more than it can do. The toning of local colour with brown paint is only a makeshift for more thoroughly mosaic work; but it is an ever-present temptation to the painter, and one against which he should be on his guard.

The actual technique of gla.s.s painting, it has been explained already, is quite different from painting as the painter understands it; often it is not so much painting as sc.r.a.ping out paint. The artist may, nay must, choose his own technique. He will get his effect in the way most sympathetic to him. What he has to remember is, that, except where he wants actually to stop out light, he must get light into his shadows--whether by stippling the wet colour, or by scrubbing it when dry with a hog tool, or by sc.r.a.ping with a point, is his affair. For example, if he wants to lower the tint of a piece of gla.s.s, the worst thing he could do would be to coat it with an even film of paint. It would be better to stipple it so that in parts more light came through.

But the best way of preserving the brilliancy of the gla.s.s would be either to paint the gla.s.s with cross-hatched lines, or to sc.r.a.pe bright lines out of a coat of paint.

In draperies, backgrounds, and so on, this is most effectively done in the form of a diaper, often as minute as damascening, which scarcely counts much as pattern. Bold or delicate, a diaper is quite the most effective means of lowering colour; even hard lines seldom appear hard in gla.s.s, owing to the spreading of the light as it comes through; but the inevitable hardness of lines sc.r.a.ped out may be mitigated by dabbing the wet paint so as to make it uneven, or by rubbing off part of the paint after the lines have been sc.r.a.ped out. Another and yet another delicate film of paint may be pa.s.sed over the painted diaper by a skilful hand, but out of each film lights should be sc.r.a.ped if the full value of the gla.s.s is to be preserved.

[Ill.u.s.tration: 56. SCRATCHED DIAPER.]

Solid pigment as local colour is a thing to indulge in only with extreme moderation. The strong black lead lines often want lines or touches of black strong enough to keep them in countenance (that is not sufficiently remembered, and it is when it is forgotten that the leads a.s.sert their harshness in white gla.s.s), and here and there, in work on a small scale, a point of black (a velvet cap, a bag, a shoe, as shown overleaf,) is very valuable as local colour; but, when the scale allows, it is better always to get this ma.s.s in dark-toned gla.s.s, which gives the necessary depth of colour most easily, most safely, and with most luminous effect.

The thing not to do, is to paint the robes of black-draped figures in black, a common practice in the seventeenth century. On the other hand, a robe of black richly embroidered with gold and pearls may quite well be rendered, as it was in late Gothic work, by solid paint, because the pearls being only delicately painted, and the gold being in great part perfectly clear yellow stain, plenty of light shines through.

As to the means of getting delicate painting in gla.s.s, the utmost delicacy can be got, but it costs patient labour, and there is risk of its going for nothing.

The only quite safe way of getting very delicate effects of painting is to paint much stronger than it is meant to appear. A very fierce fire will then reduce that to a mere ghost of what it was; possibly it will burn it away altogether. Upon this ghost of your first painting you may paint once again, strengthening it (and indeed exaggerating it) in all but quite the most delicate parts. A strong fire will, as before, reduce this without affecting the first painting. Possibly a third or even a fourth painting may be necessary to an effect of high finish. When you have it, it is as lasting as the gla.s.s itself.

[Ill.u.s.tration: 57. S. MARY'S, SHREWSBURY.]

This painstaking process, however, is found to be tedious. A much easier plan is to add to the pigment a quant.i.ty of borax, or other substance which will make it flow easily in the kiln. That necessitates only a gentle fire, in which there is no risk of burning away the work done, and enables you to do in one or two operations what would have taken three or four. But the gentle fire required to fix soft flux only fixes it gently. Securely to fix the pigment, the gla.s.s should have been raised to almost red heat, to the point, in fact, at which it just begins to melt, and the colour actually sinks into it, and becomes one with it. A heat anything like that would have wiped out soft colour altogether. Moreover, the borax flux itself is very readily decomposed by the moisture of a climate like ours. Accordingly the more easily executed work cannot possibly be fast. It fades, they say. That is not the case. It simply crumbles off, sooner or later; but eventually the atmosphere has its way with it. That is how we see in modern windows faces in which the features grow dim and disappear.

We have got to reckon with this certainty, that if we want our painting to last we must fire it very severely. What will not stand a fierce oven will not stand the weather.

In view of the labour and risk involved in very delicate painting it becomes a question how far it is worth while. That will depend upon the artist's purpose. But the moral seems to be that, for purposes of decoration generally, it would be better not to aim at too great delicacy of effect, which is after all not the quality most valuable, any more than it is most readily attainable, in gla.s.s.

Only those who have had actual experience in gla.s.s appreciate the value of silver stain. It gives the purest and most beautiful quality of yellow, from lemon to orange, brilliant as gold. There is some risk with it. One kind of gla.s.s will take it kindly, another will reject it; you have to choose your gla.s.s with reference to it. The fire may bring it to a deeper colour than is wanted. It may even come out so heavy and obscure that it has to be removed with acid, and renewed. Some all but inevitable uncertainty as to its tint, renders this peculiar yellow more suitable for use where absolute certainty of tint is not essential.

Nevertheless, the skilled gla.s.s painter makes no difficulty of doubling the process, and staining a dark yellow upon a lighter, with very beautiful results. Occasionally a master of his craft has gone so far as literally to paint in stain, sc.r.a.ping out his high lights in white, and giving, for example, the very picture of embossed goldsmith's work.

In the diapering of draperies and the like stain is of great service, and again in landscape upon blue. But it has not been used for all it is worth as a means of qualifying colour which is not precisely right, apart altogether from pattern. Many a time where a sc.u.m of paint has been employed to reduce a tint, a judicious blur of stain, not appreciable as such, would have done it more satisfactorily, without in the least obscuring the gla.s.s.

Nowhere is silver stain more invaluable than in windows of white gla.s.s or _grisaille_, the quality of which is not sufficiently appreciated.

The mother-of-pearl-like tints of what is called white gla.s.s lend themselves, in experienced hands, to effects of opalescent colour as beautiful in their way as the deeper pot-metal tones.

There is no great difficulty in combining _grisaille_ and colour, provided the white be not too thin nor the colour too deep; but the happiest combinations are where one or the other is distinctly predominant. With very deep rich gla.s.s, such as that used in the thirteenth century, it is most difficult to use white in anything like a patch (for the flesh, for example, in figure work). Unless very heavily painted it a.s.serts itself too much, and heavy paint destroys its quality. Practically the only thing to do is to use gla.s.s of really rather strong tint, which in its place has very much the value of white.

The "whites" in Early windows are a long way from purity. They are greenish, bone colour, h.o.r.n.y; but they have much more the effect of white than has, for example, pure white gla.s.s reduced by paint to a granular tint of umber.

Flesh tints present a difficulty always, unless you are content to accept a quite conventional rendering of it. In connection with strong colour you may use flesh-tinted gla.s.s; but that is just the one tint which it is most difficult to get in gla.s.s. It is usually too pink.

Painting on white gla.s.s in brown produces the most invariably happy results, and in windows into which white largely enters that is quite the best expedient to adopt. In practice it proves ordinarily a mistake to adopt a warmer brown for flesh tint, or to paint it in brown and red, as was done in the sixteenth century and after that. It looks always unpleasantly hot. When flesh wants relieving against white it is better to use a colder white gla.s.s for the background. The only condition under which warm-tinted flesh is quite acceptable is when it is in the midst of strong red and yellow. The use of red enamel for flesh seems to be a weak, unnecessary, and unavailing concession to the pictorial. It does not give the effect of actual flesh, and it does not help the effect of the window. Since you cannot get actual flesh tones it is as well to accept the convention of white flesh, which gives breadth and dignity to the gla.s.s. There is a sort of frivolity about enamelled flesh-pink.

It is, in a way, pretty, but out of key with the monumental character of a window. Gla.s.s lends itself best to strong, large work. The quality of pot-metal gives the colour chord. The leads give the key to the scale of design--the pitch, as it were, of the artist's voice. That these are strong (it is seldom worth while resorting to extra thin leads) does not argue that design must be coa.r.s.e. You have to balance them with strong work, with patches, perhaps, as well as strong lines, of dark paint, to carry off any appearance of brutality in them. This done, much delicate detail may be introduced. A strong design need not shout any more than a speaker need, who knows how to manage his voice. That is the condition: you must know your instrument, and have it under control.

Experience seems to show that a certain formality of design befits stained gla.s.s. Formality of colour arrangement soon becomes tedious; but it is seldom, if ever, that the design of gla.s.s strikes one as unduly formal.

Mosaic gla.s.s is designed, it was said above, with a view to glazing. The skilled artist designs, so to speak, in leads; but they are not the design; in fact, they count only as contours, and, except in mere glazing, they should not be expected to give lines. It is a common fault to make leads take a part in the design which they will not play in the gla.s.s.

In drawing, strong, firm, even angular lines are valuable, if not imperative. The radiating light softens them. Drawing which is already suave is likely to be too soft in the gla.s.s, to want accent. Only experience will tell you how much you must attenuate fingers and the like in your drawing in order that the light shall fill them out, and give them just their normal plumpness. The beginner never allows enough for the spreading of light.

Gla.s.s painters who know what they are about use plenty of solid painting out; but it takes experience to do it cunningly. An artist whose _metier_ is really gla.s.s is not careful of the appearance of his drawings. Cartoons are nothing but plans of gla.s.s, not intrinsically of any account. Really good gla.s.s is better than the drawings for it--necessary as good sketches may be to please the ignorant patron.

New departures in technique will suggest themselves to every inventive mind. They may even be forced upon a man--as, by his own confession, they were forced upon Mr. Lafarge--by the inadequacy of the materials within his reach, or the incompetence of the workmen on whom he has to depend. Mr. Lafarge's gla.s.s is sometimes very beautiful in colour, and is strikingly unlike modern European manufacture; but it is not so absolutely original in method as Americans appear to think. He seems to have discovered for himself some practices which he might have learnt from old or even modern work, and to have carried others a step further than was done before. The basis of his first idea, he explains, was in a large way to recall the inlay of precious stones that are set in jade by Eastern artists. That was practically the notion of the earliest Byzantine workers in gla.s.s. His use of other materials than gla.s.s in windows he might have learnt from China, Java, or j.a.pan, where they use oyster, tortoise, and crocodile sh.e.l.l; or from ancient Rome, where mica, sh.e.l.ls, and alabaster were employed. There is nothing very new in blended, streaked, or even wrinkled gla.s.s, except that moderns do by deliberate intention what the mediaeval gla.s.s-maker could not help but do, and carry it farther than they. In chipping flakes or chunks out of a solid lump of gla.s.s, Mr. Lafarge certainly struck out an idea which had probably occurred to no one since, in prehistoric ages, man shaped his arrow heads and so on out of flint. He has produced very beautiful and jewel-like effects by means of this chipping, though the material lends itself best to a more barbaric style of design than the artist has usually been content to adopt. He has appreciated, no one better, the quality of gla.s.s, but not the fact that so characteristic a material as he adopts must rule the design. The attempt to get pictorial, atmospheric, or other naturalistic effects by means of it, soon brings you to its limitations. At the rendering of flesh it comes to a full stop.

The experiment has been tried by Mr. Lafarge of a minute mosaic of little pieces of gla.s.s between two sheets of white, all fused into one; but it appears to be too costly, if not too uncertain an expedient, to be really practical as a means of rendering the human face, more especially if you want to get expression, which is there of more importance than natural colour. Another new departure, the device of blowing gla.s.s into shapes, so as to get modelling in them, results so far in rather dumb and indeterminate form.

It is quite possible to melt together a mosaic of gla.s.s without the use of lead. That practice may yet come into use in window panes, but they will be as costly as they are fragile. In larger work there is no real artistic reason why lead or its equivalent should be avoided. How much old gla.s.s would have remained to us if it had been executed in huge sheets? Here and there perhaps a broken sc.r.a.p in a museum.