American vermillion, or, as it is commonly known by most painters, scarlet lead chromate, has also been placed on the market under names or brands such as Chinese red, Persian red, Imperial Scarlet and others. It is a basic lead chromate, a pigment of great hiding power and fair permanency of color, although turning brownish on long exposure. As it does not blacken like quicksilver vermilion or fade to a pinkish white, like eosine vermillions, the Pennsylvania Railroad Company used it for over twenty-five years on their cabin cars, or cabooses, changing only recently, of which we shall speak shortly. Other systems used mixtures of this chrome red and Venetian red for their cabooses, while twenty years or more ago some implement and wagon manufacturers in the West used great quantities of it until the desire of purchasers for more brilliant reds induced them to change. It is generally made in two, but sometimes in three shades - extra light, light and dark. The writer has found some brands on the market ground in oil that were extra rich, but on examination showed that the extra brilliancy was due to the addition of a small percentage of eosine. To grind the light shade of this red in oil requires eighty-five pounds of pigment and fifteen pounds of oil for one hundred pounds of paste, and the oil should be of good body and fire boiled, otherwise it will settle quickly and is apt to cake on settling. It is best ground in iron mills of a size consistent with the amount of the batch or on roller mills, and care should be taken to prevent too much friction and heat on grinding because its color is easily damaged, producing a dull orange color. The Pennsylvania Railroad Company, who have used very large quantities, purchasing this color in the dry powder form, have lately issued preliminary specifications for cabin car red that call for toluidine red ground in oil paste form at the rate of 42 per cent by weight of pigment and 58 per cent by weight of well-settled pure linseed oil, the manufacturer who proposes to bid on the requisitions for this color to submit first a sample of the dry color for approval by their laboratory. The color is to be as non-bleeding as possible; in fact, should not bleed at all, which, however, will be found a very difficult matter to be complied with. When speaking of a pigment as bleeding it may imply that it does give up a portion of its coloring principle, as the case may be, in water or in oil or varnish, but in the case just quoted it is expected that when this red is fixed upon a surface as a paint it shall not give up part of its color to lettering or stenciling in white, as is the case with all paranitraniline reds, which color the vehicle they are ground in, and unless an isolating coat of varnish is applied over the fixed color the red will invariably strike into the white to a greater or lesser extent. This feature is not so prominent in most of the toluidine reds; in fact, there are some specimens that the writer has tested out in which bleeding is scarcely perceptible, yet it seems to be utterly impossible to find any that do not show a slight trace of the bleeding. A quick and reasonably certain test is to weigh out on a medicinal prescription scale similar portions, say five or ten troy grains of each specimen sample to be tested, and rub up on a marble slab or a slab of clean glass each of these with a similar number of drops of oil, using a clean spatula for each rub-out, which should be as liquid as a ready-for-use paint, and put a few drops of each rub-out on a piece of clean white blotting paper, when the bleeding will show itself as a yellow or brown ring about the circle of red. To accelerate the test hold the blotting paper over a flame, but not close enough to scorch the paper. Of course each of the samples on the blotter must be given as nearly as possible similar degrees of heat.
Toluidine Red surpasses any of the latest developments in the line of reds produced from coal-tar derivatives in point of permanency to light and gases, and certainly even if more costly than American vermillion it makes up for such cost to a good extent in spreading power, pound for pound of paste. It is now generally known among color makers as government fast red, and is an improvement over the lithol vermilion specified by the United States Navy Department in some of their proposals, inasmuch as it is not required to use orange mineral as the base with the toluidine red.