8 lbs. of 2nd sorted gum anime, 3 gallons of clarified oil, 1/4 lb. of litharge, 1/4 lb. of dried copperas, 1/4 lb. of dried sugar of lead, 5 1/2 gallons of turpentine;, to be all well boiled until it strings very strong, and then mixed and strained. Where large quantities are required, it will always be found best to boil off the three runs in the boiling pot. This varnish is principally intended for house painters, grainers, builders, and japanners: it will dry in two hours in summer, and in four in winter.
To make 40 gallons of gold size, put 10 gallons of oil into the iron set pot, Fig. 1, make a good fire under it, and boil for two hours; then introduce 7 lbs. of dry red-lead, 7 lbs. of litharge, and 3 lbs. of copperas, by sprinkling in a little at a time; let the oil keep boiling all the time, not in too great a heat. During the time of putting in the driers, keep stirring them from the bottom of the pot, and have the large iron ladle ready to cool it down if it should appear to rise too high; have also at hand an empty pot - the copper boiling pot will do - into which immediately ladle part of the boiling oil, if it cannot otherwise be kept in the pot, while the assistant is damping the fire with wet sifted ashes, of which there always ought to be a wheel barrowful at hand, in case of an accident. When the oil has boiled about three hours, and the driers are all in, fuse in the gum pot 10 lbs. of gum anime; and during the time of fusing, heat 2 gallons of raw linseed oil in the copper pouring jack, by placing it on the plate of the gum furnace. After the oil has been poured to the gum, and as soon as it appears boiled clear, take the gum pot from the fire; let it cool for a few minutes, then pour it into the oil in the set pot.
Wash out the gum pot, and proceed with another run in the same way. When both runs of gum are in the set pot, there are altogether 14 gallons of oil, 20 lbs. of gum, and 17 lbs. of driers; increase and keep up a regular fire in front of the furnace, that it may be drawn out in a moment, if it should be necessary. The gold size will soon throw up a frothy head on the surface, which must be kept down by constantly plying with the ladle when it is likely to rise within four inches of the pot-edge. In about five hours from the beginning of the oil boiling, it will become stringy; but the boiling must continue until it hangs to the ladle, appears quite stringy, yet drops in lumps. When tried upon the glass, if it feels sticky and strings strongly, then it is boiled enough. Draw out the fire sprinkle it with plenty of water; leave not a spark of fire in the varnish house - not even a lighted pipe of tobacco. While the maker is cooling down the pot, let the assistant have ready at the door 30 gallons of turpentine, fill the pouring pot ready, and have all the doors open. Endeavour to cool it as fast as possible, as it will require at the least one hour and a quarter after the fire has been put out before it will be ready to mix.
When the mixing commences, continue the pouring without intermission, until all the froth at the surface disappears, never stirring it until the turpentine is all in. If pouring in the turpentine has commenced while it was too hot, there will be a great loss of turpentine by evaporation; but that will not injure the quality of the gold size. Place the carrying tin close to the side of the pot, lay on the tin saddle, and strain off as quickly as possible. When all the gold size is out, pour into the set pot about 3 gallons of turpentine washings, and with the swish, wash down the pot as quickly as possible; and if the pot is still so hot as to evaporate the turpentine, ladle it out into the washings again, and pour in about 3 gallons of raw linseed oil; and with a palette knife scrape it all round, washing and cleaning it down with a rag until it is quite cleansed all round, then ladle out the oil, and wipe it completely clean and dry. The gold size ought to dry in from fifteen to twenty-five minutes, and in fourteen days it is ready for use.
Experienced makers can make gold size that will dry in five minutes, but that requires great practice.
Gum amber 16 oz.; melt in 1/2 pint of boiling hot linseed oil; add 3 oz. of asphaltum, and 3 resin.; mix thoroughly over a fire, and add when cooling 1 pint of oil of turpentine slightly warm.
Boil coal tar until it shows a disposition to harden on cooling; this can be ascertained by rubbing a little on a piece of metal. Then adu about 20 per cent. of lump asphalte, stirring it with the boiling coal tar until all the lumps are melted, when it can be allowed to cool and kept for use. This makes a very bright varnish for sheet metals, and is cheap and durable.
Dissolve, in about 2 lbs. of tar oil, 1/2 lb. of asphaltum, and a like quantity of pounded resin, mix hot in an iron kettle, care being taken to prevent any contact with the flame. When cold the varnish is ready for use. This varnish is for out-door wood and iron work. Varnish for Common Work. - This varnish is intended for protecting surfaces against atmospheric exposure. It has been used for coating wood and iron work with great advantage. Take 3 lbs. of resin and powder it, place it in a tin can, and add 2 1/2 pints of spirits of turpentine, well shake, and let it stand, occasionally shaking it for a day or two. Then add of boiled oil 5 quarts, well shake altogether, and allow it to stand in a warm room till clear. The clear portion is decanted and used, or reduced with spirits of turpentine until of the proper consistency.
A good varnish for iron is made as follows: - Take oil of turpentine and drop into it, drop by drop, strong commercial oil of vitriol; the acid will cause a dark syrupy precipitate in the oil of turpentine; keep adding drops of vitriol until the precipitate ceases taking place, then pour out the liquid and wash the syrupy mass with water, and it is ready for use. Heat the iron to be varnished to a gentle heat, apply the syrupy product and allow it to dry.