About the year 1894 the representatives in this country of some English and German manufacturers of coal-tar dyes and aniline colors visited some color makers whose line of dry colors was mostly used by paint makers with a view to disposing to them the dyestuff necessary to prepare a new line of fast reds much more permanent than the azo-scarlets and really more brilliant. These were known as paranitraniline and betanaphthaline, and at that time furnished in dry powder, leaving it to the color makers to develop the reds by diazotizing the dye and precipitating it upon such bases as they thought best. Some color makers supplying the printing ink trade had already developed a red from these dyestuffs upon a base of barytes and named the resulting material poster red ink, because it was being used for that purpose principally, being rather low priced in that quality, the coloring matter in the pigment not exceeding 5 per cent. To be short and to the point, it may be said that the experimenters at first, when making the pure red without a mineral base, despaired of ever being able to make use of the red as a paint material, because the toner, which it really was, as then made, would not dry with linseed oil or even coach japan within reasonable time. However, after a great deal of experimenting it was found that barium sulphate, in either the artificial or natural form, as blanc fixe or barytes constituted the best base upon which to fix the diazotized paranitran-iline. While some firms made three grades of the red in oil, the best carrying 16 per cent coloring matter, the next 12 per cent, the lowest 8 per cent, with a base of equal parts natural barytes and whiting as the balance of the pigment, others made their best quality 25 per cent color and 75 per cent blanc fixe, using in the mixing in oil 88 per cent of this mixture of dry pigment and 12 per cent best French orange mineral, having excellent success in marketing the goods ground in oil as well as in japan, in the latter case omitting the orange mineral.
A prominent firm of London, England, as early as 1897, although having no business connection with the American firm whatever, offered samples of what they called non-fading red, which in almost every particular equaled the product on which the latter had such a great run, but for some reason or other the red offered by the British manufacturers did not obtain any foothold in this market. By the time the Spanish war in 1898 was over, we had any number of para reds, so called for short, on the market under fancy names, the most common of which was devil's red, while the victor at Manila Bay was honored by one brand being named after him, "Dewey" red. Others used such names as permanent, perma, parma red, while others again used the word vermilion, prefacing it with a number identical with the year of their establishment in business. Prominent bulletin sign writers found it to their advantage to use the red on a blanc fixe base, its superior spreading quality equaling the difference in price, and the absence of carbonate of lime giving better wear. One great railroad system adopted for their red signals paranitraniline red of a light shade, the coloring matter to be composed of at least 23 per cent of the diazotized paranitraniline on blanc fixe, 88 per cent by weight of this and 12 per cent by weight of orange mineral to constitute the pigment, same to be ground in pure raw linseed oil at the rate of 65 per cent by weight of the dry material and 35 per cent by weight of the vehicle.
The idea of the addition of orange mineral is to add opacity to the color and to aid in its drying without the necessity of using an excess of liquid drier when thinning the paste color for application. While these reds, which we will also call para red for short, have proven themselves far superior in point of permanency to the artificial vermilions or vermilionettes, whose coloring principle was eosine, they did not give uniformly good results, and many batches of the color failed on exposure in practical use. While this could not always be traced to the coloring matter or its composition, in many cases, the failure was due to imperfect washing, the portions of caustic soda used in the process remaining in the dry color, acting disastrously on the vehicle, the paint losing its luster and streaking or turning white in a short time especially when used as an oil paint.
With the great number of para reds from orange to the deepest maroon, so-called toners, that can be obtained either pure or fixed on various percentages of inert bases, it is not difficult for the color grinder to select such as he may be in need of and mix them in such proportions with barytes, blanc fixe, china clay or whiting as may be required to suit his trade. With the litmus paper test he can readily determine if the color is free from alkali, but he must be very careful in grinding the paste that the mill does not become overheated, as this will ruin the color. When grinding para reds in paste form, that are selling at low figures for implement and wagon painting, the usual practice is to have a base of barytes when the red is for brush work, while when it is to be used for dipping, the barytes base is too heavy in gravity and whiting, clay and asbestine are substituted. In the former case 5 per cent of toner in the pigment portion is usually the limit, while in the latter case the percentage of toner must be greater because of the greater absorbing power of the base, and from 6 to 8 per cent of toner is usually required. The color grinder who works on limited capital and has a trade in proportion will find it to his advantage to grind pure toner in oil, setting it aside in well covered containers so that it will not be necessary to grind a batch every time an order is passed to him, and thereby have a lot of waste. By keeping the toner on hand in paste form in oil, he can grind his base in oil and then in a suitable mixer add the coloring matter, in such proportions as may be required to meet selling price. It is scarcely worth while to say more about these reds, as there are new types placed on the market so very frequently, and we will pass on to the red lake colors in oil that are still to be found in oil color lists, most prominent among which is Rose Pink, a deep maroon, that up to twenty years ago was made from the wood dye known as sapan wood and Lima wood, precipitated with alum as the mordant upon a base of whiting or whiting and gypsum, but is now prepared with aniline dye as the coloring principle. such as magenta or orseilline, the latter being by far the better of the two, being more fast to light and less inclined to bleed. Rose pink, being a slow drying pigment in itself, is best ground in boiled oil, as it is mostly used in the making of stains and by grainers. The usual proportions of pigment and oil required to produce a marketable paste is 72 per cent by weight of the dry material and 28 per cent of oil, varying according to the nature of the base. Like all lake colors, rose pink is very apt to liver unless well dried before mixing with the oil, and it must be free of alumina hydrate.
Rose Lake, as a rule, is simply a color of the same type as rose pink, but of at least double, sometimes treble, the strength shown by the latter, and also more brilliant in the undertone. Does not contain gypsum as a base, but usually alumina sulphate. The best grades will require anywhere from 60 to 65 per cent pigment and 35 to 40 per cent of oil to form a paste in oil.
Scarlet Lakes or Carmine Substitutes, under whatever fancy name they may be listed, are of the acid and dyestuffs substantive color type precipitated with barium chloride, and may have Bordeaux, wood ponceau or scarlet for coloring principle. This color is a decided bleeder unless well fixed upon its base of barium, and the barium chloride having changed during the precipitation process to artificial barytes, it will require a mixing of two-thirds by weight of dry pigment and one-third by weight of oil to form a paste. On exposure to strong light and noxious gases it is as permanent as carmine, which is not saying much, because in about six months either color will be almost gray under these conditions. This red is also sold as Turkey red in oil, since the red oxide sold under that name years ago has gone out of the market.
Permanent Red Lake is a name for alizarine red lake, copyrighted by a New York color maker some twenty-five years since. When this color is properly prepared, free from all traces of iron, it is a rather brilliant red, and while not as rich as carmine on first exposure, it will distance the latter in richness of tone within three months. In tests made by the writer he found that alizarine red lake after seven years' exposure showed up more brilliant by far than an unexposed sample of the same color kept under cover that length of time. This, of course, was in a measure due to the bleaching of the dried oil film in the exposed sample, while the oil film in the unexposed counter sample darkened with age. Carmine No. 40, exposed at the same time and place, had completely gone to ashy gray in fourteen months. Alizarine red lake requires its own weight of oil for a paste of medium stiffness, and the finer it is ground on a good esopus stone mill the more brilliant will be its tone.