Ceramic fiber rigidizer, where to buy?

[Com_VC]

Hi all,

Just wondering where would be the best place to source some Ceramic fiber rigidizer for sealing ceramic fiber blanket? I contacted a few places already but they only had 20 litre containers of it available. I am only after about 1 or 2 litres. I think it has a shelf life, 12 months maybe, so 20 litres would be far too much.

I'm in Melbourne, south east suburbs so somewhere around there would be good.

Thanks

[Master Splinter]

A possibility is that you could use sodium silicate as it will do that sort of job.

You can get it ready made from a pottery place (about $12/litre) or you can make your own using kitty litter and caustic soda (videos of this on YouTube) for about $3/litre. (200 grams caustic soda, 300 grams silica gel kitty litter, 500ml water).

[BobL]

A possibility is that you could use sodium silicate as it will do that sort of job.

You can get it ready made from a pottery place (about $12/litre) or you can make your own using kitty litter and caustic soda (videos of this on YouTube) for about $3/litre. (200 grams caustic soda, 300 grams silica gel kitty litter, 500ml water).

200g of caustic in 300g of Silica seems like a lot of caustic, or maybe that much is needed to dissolve the silica jell kitty litter?

The rigidizer I have has a pH of 11 which means it is alkaline but not as much as I would have thought that 200g or caustic per litre would produce.
One MSDS sheets I have seen for rigidizer claimed it only contained about 1% Na2O.

Some MSDS sheets don't mention any caustic, just 30-50% amorphous silica and some mention <10% ethylene glycol.
I assume the EG is a stabiliser for the soluble silica?.

My understanding of rigidizer is enough amorphous silica is needed between the kaowool fibres so that when the kiln is fired the amorphous silica partially melts the fibres together.
Sodium may be added to reduce the melting point of the silica in between the fibres because pure Si doesn't melt until about 1600º?
However there may enough free Na around on the fibres for the binding to take place anyway.

[NedsHead]

The chemical reaction to form sodium silicate is one part SiO2 to two parts NaOH, that works out to be 60.08 grams of silica gel kitty litter (assuming it's pure silicon dioxide) for every 79.994 grams of caustic soda, however I would add a little excess of silica gel (say 5-10 grams) to insure all of the caustic soda has been used up in the reaction.

if you're going to make your own sodium silicate use a stainless steel bowl, hot caustic soda will eat through glass

[Ueee]

You could ask Brett Selley or Gameco, Gameco sell his refactory kits which include a small amount of the rigidizer. Brett can be contacted through the ABF.
I would highly recommend putting a hardface over the blanket as well, there are many products suitable, i just use satanite. The blanket is an excellent insulator but the hardface reflects heat very well. It also makes for a more durable and easily repairable surface.

[Com_VC]

Will try and make some sodium silicate, seems easy enough to do. Though it seems I can only find 98% sodium hydroxide. Is this going to work? https://www.bunnings.com.au/diggers-500g-caustic-soda_p1560250

With the Satanite refractory will it last if I were to purchase the large 24kg bag or does it have a use by date?

Is there any other hard face alternatives, is there a diy version of it out there?


Thanks

[NedsHead]

Yeah that's fine Com_VC, you'll never get perfectly dry sodium hydroxide, it's hygroscopic and always has at least a few % water, what you don't want is aluminium added to it, I've checked the MSDS and the Diggers brand looks fine, it's even suitable for soap making, here it is in pdf, http://www.recochem.com.au/files/downloads/Caustic_Soda_Mar15.pdf