Ceramic Fibre Rigidiser?

[PeteH]

Hi all
I'm getting near to finishing insulating the dome, have put 2 layers of 1” ceramic blanket and 2 layers of 1/2” ceramic blanket on
Have secured this with galvanised mesh and ready to
apply vermicrete to return oven to dome shape before rendering
Have about a gallon of ceramic fibre rigidiser (suspect silica in solution) left over by, which I’d used on the cut edges of board when laying the floor insulation to seal the fibres
Has anyone used this on the dome blanket prior to applying vermicrete?
Was thinking of trying to harden the top 1/2 inch to produce a thin crust
Pete

[fox]

I dont think that would do you much good, it actually reduces the efficiency of ceramic fibre and would take an age to set hard without a lot of heat.
You may be able to paint it on and harden it with a flame gun but I think it will soak in to deep and need multiple coats?
you need to keep the ceramic fibre as fluffy as possible….

[PeteH]

It seemed to work well on the board when it was cut, and hardened after a week not it was a thin layer on board
I did see a you tube on heat gun hardening on fibre which seemed laborious
Will paint it on a scrap piece first and dry it the sun if our summer returns
Was hoping someone might have tried it already
Insulating with 3” blanket and a couple or 3 inches vermicrete so not too worried about losing a little depth in the fibre which I figured would happen anyway with the weight of vermicrete
Thought it might be easier to apply vermicrete over a solid layer

[fox]

I have used gallons of ceramic fibre rigidiser over many years, mainly in the constrution of high temperature stoves, it has many uses especially for sealing ceramic board, useful to stop air born fibres entering you lungs !
You should try out your idea and let us know how it works out.

[PeteH]

I’ll see how the scrap piece hardens up over a few days and if good I might try it!

info on Vitcas website

[PeteH]

Rigidiser worked ok, difficult to apply though undiluted as quite viscous, and exited sprayer as a jet rather than a spray
Diluted it 1:1 with water and added food colourant to show areas covered
soaked in maybe quarter to half an inch and hardened to semirigid layer similar to soft crust loaf of bread, but made it easy to apply 8:1 vermicrete mix (+ a little clay and 30% water by volume) without worries of loose fires and wearing PPE

Thanks Russell for showing your curved trowel, worked a treat with the vermicrete pebbledash