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bonate of lead, 4 gal. genuine kettle boiled 

 linseed oil, or 9 gal. pure raw linseed oil, 

 with $}4 pt. of Japan dryer and 1 gal. of 

 turpentine. The second coat consists of 

 100 lb. carbonate of lead, 4 gal. pure 

 linseed oil (% boiled and % raw) or 4 gal. 

 pure raw linseed oil and 1 pt. of turpentine 

 dryer. The finishing coat is prepared from 

 100 lb. carbonate of lead, ^A gal- pure 

 linseed oil (}4 boiled and % raw, or 3^ 

 gal. pure raw linseed oil and 1 pt. turpen- 

 tine Japan dryer) and I pt. of pure gum 

 turpentine. All these ingredients should 

 be the purest and best of their kind. 

 Inferior materials are likely to give un- 

 satisfactory results. Zinc white is too hard 

 for concrete painting. 



Red lead is a very good pigment for the 

 first coat on cement. It is more impervious 

 to water than white lead, is elastic, and 

 dries well. But if light color is to be placed 

 on it there is likelihood of the red staining 

 the light coat, unless a heavy second coat 

 is applied. 



As certain pigments are affected by an 

 alkali, only those immune to lime should 

 be used in painting over cement. For buff 

 use yellow ochre; for a light yellow use 

 zinc yellow (zinc chromate); for red use 

 red ochre or bright iron oxide ; for blue use 

 ultramarine blue, preferably the sulphate 

 ultramarine; for green use ultramarine 

 green or oxide of chromium green; for 

 white use zinc sulphite (lithopone), zinc 

 white not being desirable on account of its 

 hardness or lack of elasticity; for black use 

 mineral black, black oxide of manganese, 

 black oxide of iron; for gray use graphite 

 and lithopone, or lithopone and mineral 

 black. All earth pigments are safe with 

 lime; Venetian red gives a pleasing color. 



In painting on cement it is customary to 

 use plenty of turpentine, rather than much 

 oil. Also very little dryer should be used. 

 By using boiled oil we escape the use of 

 dryers entirely. Some painters use all 

 turpentine for the thinning of the first 

 coat, or nearly all, with little oil, though the 

 oil is increased with each successive coat 

 of paint. If the finish is to be dead or with- 

 out luster the first coat is thinned with 

 turpentine only, making the paint very 

 thin, adding a little varnish as a binder. 

 The next coat is similar. The third coat 

 should be thinned with 3 parts boiled 

 linseed oil and 1 part turpentine. The 

 finishing coat is thinned out with turpen- 

 tine, with a little varnish as a binder. 



A number of special coatings for cement 



Popular Science Monthly 



are on the market, guaranteed by the 

 makers to be proof against alkali. The 

 waterproofing qualities of some of these 

 preparations are overdrawn. To test such 

 a liquid, take a fairly porous brick and 

 apply to it as many coats as would be 

 placed on the cemented surface; but two 

 coats are better than one in any case, 

 particularly where a very light color is to 

 be used. Let the brick dry, then weigh 

 it, make a note of the weight, then place 

 the brick ' in a vessel with water just 

 sufficient to cover the brick; after about 

 one-half day remove brick, wipe off 

 moisture, again weigh it, and compare 

 with weight previously noted. The differ- 

 ence in weights will show amount of water 

 taken in through the paint. 



Try different paints. The one that shows 

 the greatest water-resisting power is the 

 one to use. Where concrete silos are used, 

 a waterproof paint is useful. On the inside 

 it prevents the liquid from the ensilage 

 from soaking into the wall, and as silage 

 is acid this would injure the coating of 

 cement. Tar is often used as a coating for 

 this purpose, and it does very well. 



Besides the colored coatings there are a 

 number of so-called colorless waterproof 

 cement coatings on the market. These are 

 intended for use where the color of the 

 cement is to be preserved. They are also 

 largely used as a preservative for limestone, 

 sandstone, etc. The oldest used preserva- 

 tive for this purpose is paraffin, applied 

 hot with a brush. Concerning the useful- 

 ness of the colorless liquid coatings, some 

 of them are of some value in retarding 

 moisture, but all are found lacking in the 

 following respects: They emphasize any 

 defects in, or difference in, color of concrete 

 construction; they impart to concrete a 

 s °ggy» water-soaked appearance; they do 

 not render it impervious to water for any 

 great length of time; they do not decorate. 



The following process for painting ce- 

 ment surfaces is favored by many expert 

 painters. Slake a half-bushel of fresh stone 

 lime in a barrel, and add in all 25 gal. of 

 water; when cold, after slaking, add 6 

 gal. of pure cider vinegar and 5 lb. of the 

 best dry Venetian red. Mix well and pass 

 through a 'fine strainer. Thin to the con- 

 sistency of thin cream. Apply a coat of 

 this to the cement, and after a day or so, 

 or when dry, apply a coat of red lead mixed 

 in raw linseed oil. When the red lead 

 paint has become* dry any other colored 

 paint may be applied, but care should 



