I thought of this as well. It may be something of a stretch, going with the water symbol connection, to suggest that if it were a coolant-additive or perhaps used as an emollient or emulsifier of some sort, that it could serve more than one specific use in the processing of PVCs , lacquer, - a type of plasticizer or some such.
No one knows what the symbol means, but it's still making an appearance even on the new 30th anniversary cassette edition of Alice In Chains' "Jar Of Flies"
Except the new cassette is different cuz it uses the font that was used on the EP artwork and doesn't say anything about one side being longer than the other, but then for some reason it retains the Side 1 and weird symbol design...
I think they must have stopped using this symbol, as NONE of the Judas Prist remaster CD's have this on the discs...
The only reason that symbol appears on the new Jar of Flies tape is because someone saw it on the original tape, thought it looked cool, and put it on there in the name of authenticity. I'll bet anyone any amount of money that not a single person who worked on that 30th anniversary reissue knows what that symbol actually means. Not only that, but none of us do either. At this point, can we all just accept that it's lost to history and this might be the one thing that we at the SHTV forums will never know the answer to?