Barn and Roof Paints, so called in distinction from the general line of ready mixed house and building paints to account for the difference in quality and selling price, are made to meet the demand for low prices, and the line of colors is usually confined to red, brown, slate or lead color, moss green or olive green. It is astonishing what nostrums have been sold under that name in the Far West, especially in red and brown. But we will omit a description of these and leave it to the reader's imagination, what this dope must have been when we state that such goods were sold to jobbing houses at from 30 to 35 cents per gallon in one-gallon tins at a time when linseed oil was 60 to 65 cents per gallon. Barn and roof paints are, when so branded, not recommended as the best paint for tin roofs, but more for shingle roofs that are not stained, for fences, outbuildings, etc., while for tin roofs on dwelling houses the best oxide of iron paint is none too good. Such a paint, either in red or brown, should be composed of the following ingredients: -
Red. - Sixty pounds Venetian red, consisting of 30 to 35 per cent sesquioxide iron, ground in raw linseed oil to medium stiff paste, thinned with 4 gallons (31 pounds) raw linseed oil, 5 pounds liquid drier, 1 pound rosin varnish and 3 pounds emulsion, as described previously. This paint will keep well in suspension in sealed packages and weigh 11 1/2 pounds per gallon, and if the red is well selected and free of soluble salt of iron the paint will preserve the tin for years, provided the underside of the tin has been well coated before the laying of the roof. The same applies to Brown Paint for tin roofs, when it is made as follows: - Fifty-eight pounds of metallic brown, free from the by-products of sulphuric acid plants, ground in pure raw linseed oil to medium stiff paste, thinned with 31 pounds raw linseed oil, 5 pounds liquid drier, 2 pounds rosin varnish and 4 pounds emulsion as above. This will make a paint of good covering capacity weighing 11 pounds per gallon.
Slate or Lead color of high quality for tin roofs should be composed of pigments that are not apt to scale readily, hence zinc oxide should be used sparingly or not at all. Pure white lead or sublimed white lead with a good portion of inert mineral base to reduce cost, tinted with pure oil lampblack, will give best results here. For example: 35 pounds white lead in oil, paste, 10 pounds whiting in oil, paste, and 20 pounds asbestine in oil paste, 3 pounds lampblack in oil, paste, 25 pounds raw linseed oil, 5 pounds liquid drier and 2 pounds emulsion will produce 7 1/2 gallons of a slate or lead color of medium depth, weighing a little over 13 1/4 pounds per gallon. If the paint is to be used at once the emulsion could be omitted, which will increase the weight to 13 1/2 pounds per gallon and decrease the quantity of the batch by one-quarter gallon.
When moss green or olive green for tin roof in the best quality is wanted nothing better can be offered than those greens made by the formulas given for house paints, but if the cost is too high for their use on roofs the paint maker has recourse to the inert bases described under extenders and fillers and their use, as these greens will carry large percentages of inert base before losing their hiding power. Coming back to the lower priced Barn and Roof paints for the purposes indicated above on rough surfaces, we will give a few typical formulas and of course the paint maker can vary these to suit his ideas as to cost of production. For a fairly bright red barn paint he can grind a base as follows: - Fifteen pounds native red oxide (which runs anywhere from 75 to 90 per cent in sesquioxide of iron), 15 pounds whiting and 45 pounds asbestine powder ground in raw linseed oil or, in case the market in that commodity is too high, in part linseed and part corn oil, requiring 25 pounds of oil to produce 100 pounds of paste of light gravity. Thinning this base with 20 pounds raw linseed oil, 8 pounds gloss oil, 15 pounds paint oil and 8 pounds drier will result in 13 3/4 gallons of paint, weighing 11 pounds per gallon.
Or the 100 pounds paste may be thinned with four gallons raw linseed oil, one gallon strong drier, one gallon gloss oil and two gallons emulsion, producing 14 1/2 gallons paint, weighing 11 pounds per gallon, this costing, however, a few cents more per gallon, but making a safer paint for woodwork.
A brown barn paint can be made on the same basis with the exception that the paste should be composed of the following ingredients: - Forty-five pounds metallic brown, 10 pounds whiting, 23 pounds asbestine powder, ground with 22 pounds raw linseed oil. The same rule for thinning would apply here and the weight per gallon will not materially differ from that of the red.
A lead colored barn paint can be made without the use of white lead or zinc oxide, and the use of lithopone white is suggested. Twenty-five pounds lithopone, green seal, 10 pounds whiting and 45 pounds asbestine ground in 20 pounds linseed oil, producing 100 pounds paste with from 2 to 2 1/2 pounds lampblack in oil for tinting will make a dark slate or lead colored paint when thinned with 15 1/2 pounds raw linseed oil, 15 pounds paint oil, 8 pounds gloss oil and 7 pounds strong drier, weighing 13 1/2 pounds per gallon, covering well on woodwork on barns or fences, etc. This paint will not be far in excess over the cost of red or brown and it is necessary to keep within that scope because the trade will not stand any variation in price on this line of paint, no matter what the shade or color may be. Olive green of this type is usually produced in larger establishments from remnants of higher quality brands, extended with inert base, while for the smaller manufacturer the most convenient way is to grind a suitable base on the following plan: - A base made by grinding 25 pounds American yellow ocher of good quality, 8 pounds zinc oxide, 2 pounds chemically pure green, medium, 3 pounds lampblack, 32 pounds asbestine powder in 30 pounds raw linseed oil. Thinning this paste with 23 1/4 pounds raw linseed oil, 16 pounds gloss oil, 8 pounds japan drier and 8 pounds emulsion will produce 14 gallons paint, weighing 11 pounds per gallon. For a moss green use a similar base, omitting the zinc oxide, but 3 pounds more chrome green increasing the asbestine powder to 37 pounds.