Talk Composites - The Forum for Advanced Composites

Fumed Colloidal Silica and Silicone

http://www.talkcomposites.com/Topic2929.aspx

By matthieutje65 - 9/28/2012 1:48:46 PM

I'm planning to make a silicone vacuumbag for infusion.

I see you are selling Fumed Colloidal Silica  to make a more thixotrope RESIN.
Is it possible to add it to Silicone too?

I want to make a silicone vacuumbag but I'm scared that if I brush the silicone onto the mould it will all drip off the sides and 
all fall down to the deepest point of the mould. 
Would this help to keep it better sticking to the sides of the mould or do you advice an other additive to the silicone?
By Matt (Staff) - 9/30/2012 10:45:06 AM

Hi Matthieu,

Colloidal silica would not be suitable to add to silicone to make it 'brushable' - instead you need a specific thixotropic additive for the type of silicone you're using. We actually have a thixotropic additive for our Addition Cure Silicone Rubber for this very purpose. We don't list the thixotropic additive on the website yet but we do have some and we could supply you with the small amount necessary. We also have an accelerator which makes the silicone cure within less than an hour; also helpful when you're making a re-usuable vacuum bag from brushable silicone. Lastly, we even have the stretchy net that we would recommend including within the silicone to significantly reduce the danger of tearing the bag.

In the near future we will be producing a silicone designed specifically for this purpose which will include the accelerator and the thixotropic additive already in the silicone. As you'd expect, we'll also be producing a tutorial series about this process.

In the meantime please get in touch if you'd like to pick up the various ingredients and give this a go.

All the best, Matt