Young's Demonstrative Translation of Scientific Secrets Part 13

Antimonic acid, 2 parts; sulphate of iron 1 part; flux No. 1, 9 parts. This colour is melted and sometimes a little Naples Yellow is added if it is too soft, i.e., melts too easily.

253. BLUEISH GREY FOR MIXTURES

Blue previously made by melting together three parts of flux No. 1, and one part of the mixture of oxide of cobalt, 8 parts; oxide of zinc, 1 part; sulphate of iron calcined at a forge heat, 1 part; flux No. 2, 3 parts; triturate and add a little manganese in order to render it more grey.

254. GRAYISH BLACK FOR MIXTURES

Yellow ochre, No. 244, 15 parts; oxide of cobalt, 1 part; triturate and calcine in a crucible until it has the desired tone. A little oxide of manganese is added in order to make it blacker; sometimes a little more of oxide of cobalt.

255. DEEP BLACK

Oxide of cobalt, 2 parts; oxide of copper, 2 parts; oxide of manganese, 1 part; flux No. 1, 6 parts; fused borax, 1/2 part; melt and add oxide of manganese, 1 part; oxide of copper, 2 parts; triturate without melting.

256. GENERAL DIRECTIONS

The colours thus prepared after having been rubbed up on a plate of ground gla.s.s with the spirits of turpentine or lavender, thickened in the air are applied with a hair pencil. Before using them, however, it is necessary to try them on small pieces of gla.s.s, and expose them to the fire, to ascertain if the desired tone of colour is produced. The artist must be guided by these proof pieces in using his colours. The proper gla.s.s for receiving these colours should be uniform, colourless, and difficult of fusion. For this reason crown gla.s.s made with a little alkali or kelp is preferred.

A design must be drawn upon paper and placed beneath the plate of gla.s.s. The upper side of the gla.s.s being sponged over with gum-water affords, when dry, a surface proper for receiving the colours, without the risk of their running irregularly, as they would be apt to do on the slippery gla.s.s. The artist draws on the plate, with a fine pencil all the traces which mark the great outlines and shades of the figures. This is usually done in black, and afterwards, when it is dry, the vitrifying colours are laid on by means of larger hair pencils. The yellow formed with chloride of silver is generally laid on the back of the gla.s.s, for it is apt to run with the other colours while heating.

The pigments used in painting on gla.s.s are princ.i.p.ally 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 gla.s.s, and exposing them to heat in a m.u.f.fle. The painter is guided by these trial pieces in laying on his colours. To fire the paintings a furnace with a m.u.f.fle is used. The m.u.f.fles 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, pa.s.sed 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 -------- 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 -------- 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 ma.s.s.

260. STONE-COLOURED PAINT

Lime-water, 4 galls................. $0.04 Whiting, 112 lbs.................... 1.12 White lead, ground, 28 lbs.......... 2.24 Road-dust, 56 lbs................... 0.10 Prepared fish oil, 2 galls.......... 1.20 Incorporated oil, 3-1/2 galls....... 2.00 Linseed oil, 3-1/2 galls............ 3.15 -------- Weights, 293 lbs....... $9.85

The above stone-colour fit for use, is not three and a half cents per pound.

261. BROWN-RED COLOURED PAINT

Lime-water, 8 galls................. $0.08 Spanish brown, 112 lbs.............. 3.36 Road-dust, 224 lbs.................. 0.40 4 galls. of fish oil................ 2.40 4 galls. incorporated oil........... 2.28 4 galls. linseed oil................ 3.60 -------- Weights, 501 lbs....... $12.12

This paint is scarcely two and a half cents per pound. The Spanish brown must be in powder.

262. A GOOD CHOCOLATE COLOURED PAINT

This is made by the addition of blue black in powder, or lamp-black to receipt No. 261, till the colour is to the painter's mind; and a lighter brown may be formed by adding ground white lead. By ground lead is meant white lead ground in oil.

263. YELLOW PAINT

This is prepared with yellow ochre in powder, to receipt No. 261, in the same proportion as Spanish brown.

264. BLACK PAINT

This is also prepared in the same proportion, as in receipt No. 261, using lamp-black or blue-black, instead of Spanish brown.

265. WHITE PAINT

Slack a peck of nice, clean, fresh lime in a covered vessel, with water which is boiling hot; when well slacked, strain it well, then add to it 1-1/2 lbs. of finely ground rice; let the rice be boiled to a thin paste, and stirred in while very hot; 1/2 peck of common salt, well dissolved in warm water; 1/2 lb. of clean glue, dissolved in water; and 1/4 lb. of whiting; when well mixed, add 5 gallons of very hot water, then stir well, and let stand a few days well covered. Pit it on hot, and it will stand the weather as well as a good deal of white lead. You may colour this paint to suit your taste, using and stirring in well Spanish brown for a red pink colour. Take common clay finely powdered, and mixed well with Spanish brown for a reddish stone-colour. For yellow colour use yellow ochre if you please, but chrome yellow makes a richer colour and less does. You may make the colours dark or light according to the quant.i.ty of colouring matter used.

266. COMPOUND COLOURED PAINTS

The various colours that may be obtained by the mixture of other colours, are innumerable. I only propose here to give the best and simplest modes of preparing those which are required for use.

Compound colours, formed by the union of only two colours, are called by painters virgin tints. The smaller the number of colours of which any compound colour is composed, the purer and the richer it will be. They are prepared as follows:

267. LIGHT GREY

This is made by mixing white lead with lamp-black, using more or less of each material, as you wish to obtain a darker or lighter colour.

268. BUFF COLOUR

This is made from yellow ochre and white lead.