Hi good morning, i have been hearing a few guys at this site talking about makeing coloidal silica out of fumed silica, my Questain is what type, and size particle of fumed silica will make coloidal silica rigidizor' if any one Knows Thanks.

I'm not sure about particle size or anything like that, but if you look for hydrophilic fumed silica you can find it pretty cheap. I've got some cab-o-sil on the way, if not arrived already in the box I tripped over by my door. It's mentioned on the forums multiple times, and it seems to be the general consensus for a "right" ratio is 1 cup of fumed silica to 16 fl oz of water.

Of course, this stuff is definitely in the WEAR YOUR PPE category. So a respirator is definitely high on the list.

From what I can find on t'internet, 14 nanometre seems to be about the optimum particle size for getting the concentration high. I don't know what that relates to in terms of specific area. 

The commercial rigidizer I've used in the past had a Specific Gravity of a little over 1.1. The best I managed to get with Cab-O-Sil M5 was about 1/7th of that concentration: an SG of around 1.015. This was multiple volumes of the Cab-O-Sil in a volume of water.

It was the low achievable concentration that had me researching particle sizes and concentration online.

Low concentration seems to be no real problem if you have time and good drying conditions: you just make multiple applications. 

 

Read, " My consolidated notes for new forge builders" , posted by  

Lou L it has most of the info you may need.

Good luck

Pnut (Mike) 

It doesn't however have any info on particle size. 

Fumed silica IS colloidal. I picked it up for not much at all at a local fiberglass and plastics supply place, it's commonly used as a thickener for fiberglass resin, paint, plaster, etc. 

Frosty The Lucky.