Detector crayon

By March 1942 a number of blister gas detectors, all of which were based on color changes in a dye base and had their origins in British and American developments in 1918, had been standardized. They included the M4 vapor detector kit, capable of registering even faint concentrations of nitrogen and sulphur mustards M5 liquid vesicant detector paint M6 liquid vesicant detector paper and M7 vesicant detector crayon, sensitive to mustard and lewisite. Although the CWS had not discovered a better dye base than that developed by the British, NDRC chemists at the University of Chicago, at the University of Virginia, and at Ohio State improved its composition and developed new detector materials. ... 

Other miscellaneous protective items which the CWS procured under contract were gas resistant aprons, made of impermeable cloth and intended for use by certain Medical Corps and CWS troops gas resistant sacks for shipment of contaminated clothing to decontaminating stations and various items for detecting such gases as vesicant detector crayons and liquid vesicant detector paper and paint. 

Lumogen . [BASF] Fluorescent yeUow pigment for prod, of wax chalks, crayons, crack detectors. 

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