The pigments used in painting on glass are principally matallic oxides and chlorides, and as, in most of these, the colour is not brought out until after the painting is submitted to heat, it is necessary to ascertain beforehand if the colours are properly mixed by painting on slips of glass, and exposing them to heat in a muffle. The painter is guided by these trial pieces in laying on his colours. To fire the paintings a furnace with a muffle is used. The muffles are made of refractory clay.
257. WHITE COATING FOR GOLD VARNISHES
A quart of strong parchment size and half a pint of water are to be made quite hot, and to these are to be added, (in small portions from time to time,) two good handsful of common whiting, passed through a fine sieve; this mixture is to be left to infuse for half an hour, when it is to be stirred carefully so that the amalgamation may be perfect. This coating is preferable to any glue or cement for coating picture frames, &c., on which is to be laid the tin or silver leaf, to be varnished with gold varnishes or lackers.
258. LEAD COLOURING PAINT
Whiting, 112 lbs…………………. $1.12
Blue-black, 5 lbs………………… 0.25
White lead ground in oil, 28 lbs…… 2.24
Road-dirt, 56 lbs………………… 0.10
Lime-water, 5 galls………………. 0.05
Residue of the oil, 2-1/4 galls……. 1.25
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Weights, 256 lbs……. $5.01
To the above add two galls. of the incorporated oil, and 2 galls. of the linseed oil to thin it for use, and it will not exceed two cents and a quarter. The lime-water, whiting, road-dirt, and blue-black, must be first mixed together, then add the ground lead, first blending it with 2-1/2 galls. of the prepared fish oil; after which, thin the whole with 2 galls. of linseed oil and 2 galls. of incorporated oil, and it will be fit for use. For garden doors, and other work liable to be in constant use, a little spirits of turpentine may be added to the paint whilst laying on, which will have the desired effect.
259. BRIGHT GREEN PAINT
112 lbs. yellow ochre in powder at 5 cts. per lb…. $5.50
168 lbs. road-dust……………………………. 0.25
112 lbs. wet blue, at 20 cts. per lb……………. 22.40
10 lbs. blue-black, at 5 cts. per lb…………… 0.50
6 galls. of lime-water………………………. 0.06
4 galls. fish oil, prepared………………….. 2.40
7-1/2 galls. incorporated oil………………… 4.28
7-1/2 galls. linseed oil, at 90 cts. per gal…… 6.75
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Weights, 592 lbs………….. $42.24
It will be seen that the bright green paint costs but about 7 cts. per lb., ready to lay on; and the inventor challenges any colour-man or painter to produce a green equal to it for five times the price. After painting, the colour left in the pot may be covered with water to prevent it from sinking, and the brushes, as usual, should be cleaned with the painting-knife, and kept under water. A brighter green may be formed by omitting the blue-black. A lighter green may be had by the addition of 10 lbs. of ground white lead. Observe that the wet blue must be ground with the incorporated oil, preparatory to its being mixed with the mass.