I have contacted GPI a couple of times but to no avail. I see they are now owned by a Japanese company called Angel so have contacted them too. I'm not holding my breath that they will get back to me so I'll ask here as I'm sure that somebody will know something of interest.
Does anybody knows what materials/chemicals were used to produce BetG early 1960s plaques. I ask as there are a number of "theories" with urea-formaldehyde being the main "culprit" although cellulose acetate has also been mentioned due to the smell (vinegar syndrome). Acryllic would be too early I assume but doubtless there are other possibilities too.
I've been told that the middle is called clay (in the industry) although is actually more of a bakelite material (again, so I've been told) which seem to be pretty hard wearing and most have just gone a creamy colour over the years but, again, more info would be useful.
Obviously I am trying to find out in relation to the Le Cercle plaques made in 1961. Their main "claim to fame" is that they used in the Dr No/A Hard day's night films and are one of the few crossover gaming items I know of (in that they are real casino plaques and also film props) from the UK. Or the most well known at least. Playboy Thatched Barn are probably the next.
They also have a "shelf life" although that is probably more down to how carefully they are looked after (and stored) than the chemical composition but it would be nice to see if anybody knows more about the process of how they came up with the material used so it could maybe be worked out a little more accurately (sort of).
I have ones that are in perfect condition (and look like they were made yesterday) but the vast majority of them have warped, shrunk and gone pretty "nasty" although the ones in-between aren't actually that bad, considering. The ink seems to be still in "liquid" form, as I found out when washing them, and I did pop some of the "spots" on the back (where the ink has seeped from elsewhere within) to get the ink out as it makes unsightly ink blotches on the back. Weirdly, most are in the same places (many to choose from) but maybe that's because of other factors unknown to me. I only did a couple to confirm that the ink was still "wet" plus I was curious to see if it was possible. The plaques looked a little better afterwards but not something I would ever do to any other plaques.
Thanks for any help/advice in this query and I hope that somebody knows enough about these specific BetG 1960s era plaques to help me narrow it down.