Chevreul was one of the first pioneers in this field of research to observe the effects of colored lights on drying, and he claimed that oil exposed under white glass dried more rapidly than when exposed under red glass, which eliminates all light of short wave lengths.
Genthe obtained interesting results in the drying of oil submitted to the effect of the mercury lamp. Oxidation without driers was effected probably through the formation of peroxides. In commenting on this subject, Blackler[4] gives a description of the use of the Uveol Lamp, which is similar to the mercury lamp, but has, instead of a glass casing which cuts off the valuable rays, a fused-quartz casing which allows their passage.
[4] M. B. Blackler: “The Use and Abuse of Driers,” P. and V. Society, London, Sept. 9, 1909.
Driers in Boiled Oil. In the boiling of linseed oil, by certain processes the oil is heated to 250° F. and manganese resinate is incorporated therein. It goes into solution quite rapidly. In other processes the oil is heated to 400° F. or over, and manganese as an oxide is boiled into the oil. Although it is unsafe to say that a small percentage of rosin, such as would be introduced by the use of resinate driers, is not harmful, yet it appears that this process should give a good oil, inasmuch as it has been found that no matter whether the manganese is added to the oil, as a resinate, borate or oxide, practically the same drying effect is noticed in every case where the percentage of manganese is the same. It is the opinion of some, however, that the resinate driers are not as well suited for durability as oxide driers. However, if a boiled oil is found to contain on analysis a small percentage of rosin less than 0.5% or a percentage only sufficient to combine with the metal present, it should not be suspected of adulteration. Practical tests should be made with such oil along with an oil made with an oxide drier, before pronouncing on their relative values. Inasmuch as the addition of certain driers to linseed oil lessens the durability of the film, it is more practical to use the smallest amount of drier that will serve the purpose desired, that is, set the oil up to a hard condition which will not take dust and which will stand abrasion.
The results of this investigation would indicate that when lead or manganese linoleates are used, the most efficient drying is shown with 0.5% lead or with 0.02% manganese, or with a combination of 0.5% lead and 0.02% manganese.
Until more definite results have been obtained with the tungates, which will probably prove of exceptional interest as driers, the above driers will probably be used to the greatest extent.
Co-operative Drying Tests. A series of important drying tests made by members of a special committee[5] appointed by the American Society for Testing Materials, of which the writer was chairman, is herewith shown:
[5] Sub-Committee C of Committee D-1, on Testing Paint Vehicles. Proc. Amer. Soc. for Test. Mater., 1911.
“At the January meeting of Committee D-1, a sub-committee consisting of the following members was appointed to investigate paint vehicles:
| G. B. Heckel, |
| Glenn H. Pickard, |
| Allen Rogers, |
| A. H. Sabin, |
| H. A. Gardner, Chairman. |