I hesitate to send yet another posting on the subject of silicone rubber
as a pouch sealant.  Although silicone rubber has 14 letters a number of
subscribers consider it a 4-letter word.  This posting is thus addressed
only to those of you who are tempted to try out the compound.

MMD subscriber Bing Gibbs has sent me on a sample of silicone rubber
3-1765 and asked me to evaluate it as a sealant.  This is a low viscosity
compound used in the electronics industry for coating printed circuit
boards etc.  It's very easy to use but unfortunately does not seal too
well.  Bing also asked me to check out various solvents and dilution
ratios for the previously mentioned Dow 734 and 732 compounds.  (The 734
is a free flowing silicone rubber whereas the 732 is equivalent to
ordinary bathroom caulk.)

The only two solvents that seem to give consistent results are naphtha
(lighter fuel) and toluol (toluene).  I did not even try lacquer thinner
since its composition varies greatly from brand to brand.

In a previous posting I suggested a dilution ratio of 1:1.  However, a
ratio of about 1:2 yields a thinner solution that is much easier to use.
Test measurements indicate that this thinner solution seals equally well.
For those of you who are disinclined to measure quantities , a 1:2
dilution will give you a liquid about the consistency of maple syrup or
olive oil.

The silicone rubber works so well as a sealant that any residual leakage
appears to come through the edge of the pouch leather.  I think it would
be helpful to seal the complete area of the leather pouch -- not just the
area over the pouch well.

For those of you who want to try silicone rubber as an alternative I hope
you may find this helpful.

Phil Dayson