CHAPTER XXI 
ENAMELLING 
Tools and materials—List of enamels. 
Enamelling is here dealt with technically. For a true appreciation of theartistic and historical side of this supreme craft the reader is referred to a little book on Enamels by Mrs. Nelson Dawson, herself one of its most gifted exponents. 

Let us look first at the material itself. Enamel is a kind of rather soft glass—composed of flint or sand, red lead and soda or potash. These ingredients are melted together and produceanalmost clear glass with aslightlybluishorgreen ish tinge. This almost colourless material is known as flux or frit. It is made in different degrees of hardness,—those kinds which contain more lead and potash are more brilliant, but softer. Soft enamels require less heat to fire them, and are, therefore, convenient to use, but they do not wear so well. So for any work which has to stand friction hard enamels are essential. Clear flux or frit is the base from which coloured enamels are made,—the colouring matter being metallic oxides. The addition of two or three per cent, of one of these oxides is generally sufficient to produce a strong enough colour. The enamel, after being very thoroughly stirred, is poured out into cakes four or five inches in diameter. It is afterwards broken up, ground in a mortar to a fine powder, thoroughly washed, and spread evenly over the surface of a piece of metal. It is then placed in a furnace and fused. The firing enables the enamel to hold firmly on to the metal. Such in its simplest terms is an enamel—a vitreous substance fused on to a 
metallic background. The tools required for enamelling are not many, the furnace being the principal one, Fig. 273. Furnaces are made in many patterns and are heated by gas, electricity, coke or oil. Gas-heated furnaces are the most generally used. They con-fist of a muffle surrounded by a casing of specially prepared fireclay. Fletcher gives 1 part fireclay to 3 or 4 parts saw dust, moistened, worked into form and burnt, as the material from which furnace casings are made. Heat is supplied to the furnace by a row of Bunsen burners under neath. To avoid the heat radiated by the chimney it is well to fix a shield before it. Some enamellers use also a hanging glass screen as an additional protection. A small enamel may be fired in an ordinary clay crucible heated by the blowpipe, or even in a piece of iron folded in half; but the enamel should not be exposed to the direct blast of the flame, or it may be discoloured. This method, however, is rather dangerous for firing small silver articles—they melt so easily. A pair of tongs about two feet long, with slender handles and jaws, is necessary, Fig. 276. One or two palette knives, with blade about a foot long, are useful for lifting the work on and off the metal plate on which it rests for firing. 

A set of boxes, or of wide-mouthed bottles, to hold the enamels should be numbered to correspond with the printed list of colours as supplied by the makers. It is a good plan also to have a set of samplers of the different colours, prepared in the following manner. Take a number of plaques of thin copper, measuring, say, ljinch by 1 inch. Dome them up as described on page 197. Coat onethird of the surface of each with white enamel, one third Avith clear flux and the remainder with the enamel you wish to test. Fire them. Then lay a strip of silver foil, prepared as described on page 202, across the three stripes as indicated in Fig. 274. Cover the foil, the white, and the flux with a coating of the coloured enamel; and fire the plaque again. You will now have a sampler which shows how the colour will look when fired directly on to copper; and when fired on flux, on white, and on foil. The colour will look quite different on each. It will be most brilliant on the foil, next on the white or the flux, and deepest on the copper. It is only necessary now to paint the number on the sampler, and a figure to indicate if it is a soft, hard, or very hard colour. You decide this by arranging small pieces of all the enamels you wish to test on a plaque, and noticing the order in which they fuse when in the furnace. You should take care in doing this that all the colours are ground equally fine, and that the heat of the furnace reaches them all to the same extent. 

In addition to the above, the following will be required, —one or two porcelain pestles and mortars, Fig. 277; a small agate pestle and mortar, and one or two small spatulas, Fig. 275; a set of little china pans to hold the enamels when ground, Fig. 278; a slab of plate glass and a glass muller, Fig. 279, for grinding colours for painting with; a corundum stick, and polishing materials; tools for en graving and repousse work; rouge or whiting to protect any solder on the work from the heat of the furnace; some gum tragacanth dissolved in water. Cunynghame, in his book on Enamelling, says that the best way to dissolve the gum is to powder it well and wet it with alcohol before putting it in water. A porcelain dish and some fluoric, nitric, and sulphuric acids complete the list. 

The metals usually employed for enamelling on are copper, silver and gold. Enamel will not hold on com mercial brass, though it will on some bronzes. Iron can be enamelled, as we know to our sorrow, for enamelled iron advertisements are fairly plentiful. Platinum will not hold enamel well, though it may be used in small pieces for foil. It is almost impossible to induce enamel to stay upon electrotypes; and of course, the softer metals—aluminium, tin, zinc, etc., will not stand the heat necessary for the fusing of the enamel. But in gold, silver and copper we have three splendid metals for our purpose. 

Silver or gold foil (over which a thin coating of colour is fired) is often employed to produce a brighter spot of colour than could otherwise be obtained; for translucent colours look brighter on gold or silver than on copper. 
Enamel is applied to the work in a number of different ways. It will be well, therefore, for closer examination, to divide enamels into the three groups suggested by the late Sir A. W. Franks. 

1. Inlaid enamels, where the outlines are formed by metal divisions. This group includes champleve and cloisonne enamels, and those without backgrounds, known as plique a jour. 

2. Transparent enamels, where the outlines and other markings are produced by variations of depth in the sculptured ground over which the vitreous substance is floated. These are known as bassetaille. 

3. Painted enamels, where the outlines are made by a difference in tint of the enamel itself,—the enamel com pletely covering the metal base beneath. 

There are a few enamels extant, such as those on the Ardagh Chalice, which do not come completely within any one of the above groups. They will be discussed afterwards. 

A list of useful enamels is given below. The numbers correspond with those of Soyer, of Paris, the well-known makers of enamel colours. To commence with, those marked with a dagger (Editor: Changed to *) should be purchased. One or two ounces of each, would be sufficient, except for No. 3. Silver flux goes well on copper. 

Transparent Colours. 
*2. Flux for gold.  *29. Lilac, No. 1. 
*3. Flux for silver.      *32. Maroon, S.M. 
14. Brown.    *36. Black, No. 62. 
15. Yellow. 40. Red, dark. 
*17.Yellow No. 3.    *41. „ clear. 
19. Red, cerise.    *44. Rose, flesh. 
21. Violet, No. 52.      *45. Turquoise, Star. 
53. „ Star.    *48. Green, No. 3. 
123. Blue.    *52-» Star, 
*27. Blue  Ship, 


Opaque Colours. 
*54. White, Ship. 82. Turquoise, No. 1. 
61a. White  No. 5 (tinted full cream 84. Green, half dark). 
69. Pale blue. 90. Blue, opaque.  88. Grey, pearl. 
70. Grey, coffee colour. *72. Ivory. Iridium black, prepared for painting
75. Yellow, light.