The Gray Stamp Company was one of the common approval companies from back in the day based in Canada. As suggested by others, the quality of the material (as packets) is typically low, so soaking the stamps will not diminish much of any value for you.
I saw an on-line ad from Popular Mechanics back in the 1920s when the Gray Stamp Company was marketing a packet of stamps for a mere two cents (of course, that covered postage and presumably approvals followed).
For some background on the Gray Stamp Company, which eventually evolved into the Empire Stamp Corporation, consider this ad from 1970:
