(21) A better method, however, of preparing oil-cloth is first to cover the cloth or canvas with a liquid paste, made with drying oil in the following manner: Take Spanish white or pipeclay which has been completely cleaned by washing and sifting it from all impurities, and mix it up with boiled oil, to which a drying quality has been given by adding a dose of litharge, 1/4 the weight of the oil. This mixture, being brought to the consistence of thin paste, is spread over the cloth or canvas by means of an iron spatula, equal in length to the breadth of the cloth. When the first coating is dry, a second is applied. The unevennesses occasioned by the coarseness of the cloth or the unequal application of the paste are smoothed down with pumice, reduced to powder, and rubbed over the cloth with a bit of soft serge or cork dipped in water. When the last coating is dry, the cloth must be well washed in water to clean it; and, after it is dried, a varnish composed of lac dissolved in linseed oil boiled with turpentine is applied to it, and the process is complete. The colour of the varnished cloth thus produced is yellow; but different tints can be given to it in the manner already pointed out.
An improved description of this article, intended for printed and figured varnished cloths, is obtained by using a finer paste and cloth of a more delicate texture.
(22) Varnished Silk
This material, often employed for umbrellas, is prepared much in the same manner as (21), but with a paste composed of linseed oil boiled with 1/4 litharge, 16 parts dried and sifted pipe-clay, 3 of litharge very finely ground, dried, and sifted, and 1 of lampblack. After washing the silk, fat copal varnish is applied instead of that used for oil-cloth.
(23) For Linen
A solution of alumina sulphate in 10 times its weight of water, and a soap bath of the following composition: 1 oz. light coloured rosin and 1 oz. crystallised soda are boiled in 10 oz. water until dissolved. The rosin soap is precipitated with 1/2 oz. table salt, and is subsequently dissolved along with 1 oz. white curd soap in 30 oz. hot water. It should be put in wooden tubs for use. On made up articles, the two solutions can be applied with a brush and then rinsed off.
(24) Parone, of Turin, proposes the following method of rendering textures waterproof. In 14 pints of water, heated to about 180° F. (82°C.) dissolve 10 1/2 lb. gelatine and 21 lb. castor-oil soap; then add 10 1/2 lb. lac, shaking the liquid till the lac is completely dissolved. Take it off the fire, and add to the mixture in small quantities at a time 21 lb. powdered alum, shaking it till the alum is dissolved. The liquid thickens, forming an insoluble alumina soap which remains closely incorporated with the gelatine and lac. It is spread over the textures with a brush.
(25) Cooley gives the following recipe for waterproofing, which appears to have the advantage of having been tried with success: - "A simple method of rendering cloth waterproof, without being airproof, is to spread it on any smooth surface and to rub the wrong side with a lump of beeswax (perfectly pure and free from grease), until it presents a slight, but even, white or greyish appearance; a hot iron is then passed over it, and, the cloth being brushed whilst warm, the process is complete. When this operation has been skilfully performed, a caudle may be blown out through the cloth, if coarse, and yet a piece of the same placed across an inverted hat may have several glassfuls of water poured into the hollow formed by it, without any of the liquid passing through. Pressure or friction will alone make it do so."
(26) For Canvas
The following is highly recommended as a cheap and simple process for coating canvas for wagon tops, tents, awnings, etc. It renders it impermeable to moisture, without making it stiff and likely to break. Soft soap is dissolved in hot water, and a solution of iron sulphate adaed. The sulphuric acid combines with the potash of the soap, and the iron oxide is precipitated with the fatty acid as insoluble iron soap. This is washed and dried, and mixed with linseed oil. The soap prevents the oil from getting hard and cracking, and at the same time water has no effect on it.
(27) Waterproofing Oil
Take 20 oz. lard oil, 10 oz. paraffin, 1 oz. beeswax; heat the oil over a slow fire, and when hot add the paraffin and wax; allow the whole to remain over the fire until the latter articles are melted, and add a few drops of sassafras oil or other essential oil to preserve it.
(28) Sailcloth Impervious To Water, Yet Pliant And Durable
Grind 6 lb. English ochre with boiled oil, and add 1 lb. black paint, which mixture forms an indifferent black; 1 oz. yellow soap dissolved by heat in 1/2 pint water, is mixed while hot with the paint. This composition is laid upon dry canvas as stiff as can conveniently be done with the brush. Two days after, a second coat of ochre and black paint (without any soap) is laid on, and, allowing this coat time to dry, the canvas is finished with a coat of any desired colour. After 3 days it does not stick together when folded up. This is the formula used in the British navy yards, and it has given excellent results. A portable boat may be made of canvas prepared in this way, and stretched on a skeleton frame.
(29) For Woollen Cloth
1 oz. powdered alum, 4 1/2 oz. sugar of lead, dissolved in 3 gal. water, and stirred twice a day for 2 days. When perfect subsidence has taken place, pour off the clear liquid only, and add to it 2 dr. isinglass, previously dissolved in warm water, taking care to mix thoroughly. Steep the garments in this mixture for 6 hours, after which hang up to drain and dry. Wringing must be avoided. This recipe is used by woollen-cloth waterproofers.
(30) Dujardin's process for all kinds of textiles is as follows. Place in a mortar 12 oz. alumina and potash sulphate reduced to powder, and 12 oz. lead acetate; bray till the mixture is quite deliquescent. Add 7 oz. pulverised potash bicarbonate, and 7 oz. soda sulphate; bray till completely combined. Pour in 4 1/4 oz. calcined magnesia, and continue braying while adding 8f pints water. Pour the whole into a bucket containing 11 gal. river or rain water, which must be fresh. Shake the whole until there is complete solution, which takes place in 20 minutes. Pour the liquid thus obtained into a convenient receptacle holding about 22 gal.; in which have been dissolved 5} lb. oleine soap in 11 gal. rain or river water. Boil for about 20 minutes. To render-a texture waterproof, it is then sufficient to put in this liquid either by hand or machinery, until it is perfectly impregnated in all its parts. Care must be taken during the whole operation to stir the mixture well, that no deposit may be formed. The texture is then withdrawn, left to drip, and dried. It is afterwards washed in plenty of water, dried, and dressed as usual. In this condition the texture is waterproof, but penetrable by air, which is indispensable for health.
This process does not alter tints at all, but if the materials have very delicate tints, it is necessary to take account of the composition of these colours, and compose the bath accord-. ingly. The potash bicarbonate and soda sulphate must then be sometimes le-placed by the same quantity of salts of iron, copper, zinc, lead, or some other metallic salt suitable for preserving colours. To prepare linen, leather, or wood, add 3 1/2 oz. margarine to the bath. When it is desired to prepare cotton or paper, it is well to add to the bath 1 3/4 oz. gelatine, and 3 1/2 oz. light-coloured rosin. After that, dry in the open air or at the fire, and the products will be perfectly impermeable, and resist every kind of washing. Paper paste may be even soaked in the vat, and thus an impermeable paper obtained, the above process replacing the sizing.