[Stoves] Sodium Silicate

[Crispin Pemberton-Pigott]

Dear Friends

I am in Mulanje, Malawi and met a Rocket Stove manufacturer from
Uganda who is using a ball clay+ball clay grog+sodium silicate 2% mix
to make a very strong combustion chamber.

In a lengthy discussion last night it became clear that no one in the
room knew what the chemistry of this bonding is.

Can anyone perhaps enlighten the group how such a small amount of
sodium silicate works.  There are apparently two forms of it, one that
works and one that doesn't.  It comes as a powder (good) and paste
(bad).

The units are fired afterwards to 1000 C so perhaps the product has
both chemical and ceramic bonding.  I feel there are chemical bonding
processes that may be more valuable for our processes than low
temperature ceramic bonds.

I have seen some phosphate bonding attempts made there by Andi and it
does not look promising - it appears they are changing shape a lot on
firing, for some reason.

The Ring Maker modified to produce pot rest rings is doing a
marvellous job.  I would say they are close to perfecting that
component.

And it is nice to see Piet Visser who is here for the conference!

Regards
Crispin