Vermicrete - adding Sodium Silicate

[PeterW]

Just a quick note on an 'experiment' I tried at the weekend.

I took a standard mix of 2L OPC, 3L Water and 10L of vermiculite and added about 250ml of 75% Sodium silicate solutoin. I used the advised way of mixing the OPC and water first, then added the sodium silicate and finally the vermiculite.

Within 3 hours the mix had firmed up dramatically, and within 24hrs it had become very firm. This is in contrast to the last lot I made which took 5 days to go off properly, and still didn't completly set up as I would like it.

Sodium Silicate is used in refractory mixes, and its certainly something I would recommend if anyone has an easy source - obviously, I'd be interested to see how anyone else gets on !

Cheers

Peter

[Carl]

I used water glass (sodium silicate) in my oven - I used it to make a mouldable insulation mix, because the sodium silicate will withstand much higher temperatures than portland cement, and it sets much quicker than a pure portland mix.

A couple of my posts on sodium silicate:

http://www.fornobravo.com/forum/3/an...html#post27142 (Another UK oven started)

http://www.fornobravo.com/forum/8/fi...html#post30664 (Is fireclay necessary?)

A good link to using it for refractory mixes is here:

Perlite/silicate composites

There's a bit more detail on my blog too, on how I used the insulation mix to coat the inside of my chimney to round off some rough edges. I'll be using the same mix to make the door.

Carl

[Carl]

Should have added - I bought my sodium silicate from clayman supplies - link here: Miscellaneous Medias & Materials

Carl

[david s]

Carl,
Thanks for the sodium silicate info. I use it for slip casting. That is a thick mixture of clay and water that is solid enogh to pick up in a handful. When you add a small quantity (30 ml or so) of sodium silicate to a bucket full of this slip, once you start to mix it the whole bucket becomes quite liquid like pouring cream, without having to add more water, which is what you want to get rid of into the plaster mould. Magic stuff.