hi everyone, thanks for the responses,

i have had this happen only 3 times,
on one occasion i was tumbling a combination of obsidian and beach glass, on another occasion it was aplite, in these two instances they were both at stage 2 (120/220 silicon carbide grit) and the tumblers leaked all over,at that point in time i was in the habit of putting sugar in with the rocks, water and grit in particular to help thicken the slurry and hope to avoid chipping - i wondered if the sugar was somehow converted to an organic gas. since then i do not add sugar.

the most recent case was beach glass - i caught it in time (no leakage) and release the gas daily and it has not leaked, but the tumbler visibly bulges if i leave it too long. it was, again, stage 2 grit.

i have seen, on line, a statement that this gas forming phenomenon usually occurs with glass (man made or natural (ie obsidian)) which would fit win 2 of my 3 cases)but no explanation of why was given.

Mike, I had not thought of starting with hot water , that is an interesting idea. I do not think there is much organic material on my rocks before i tumble them, i clean them really well, in fact i usually have preground them on a grinding wheel, and in particular, the beach glass, i believe, was really clean before it was tumbled!

anyway, i find it interesting,

thanks for hte input

Carl

From carl - August 25, 2008 at 08:33:48

Message: 66917