cast riser questions

Gary B here. I am fully under way building my second rocket stove. Today I am here asking for advice on the best casting material for my riser. I have the mold all completed and I want to choose the best product and ratios I can get. I live in central MN. I have went to the fancy builder places and looked at a bunch of different products, mason mortars and what have you. Every time I explain what I am doing they say there product won't work. I have read the bags and I can't find any temperature ratings and certainly no info on adding perlite.

So if some one could give me a brand name and exact product number I could search for this would really help me out. My riser mold is 10 inch out side diameter and 6 inch inside diameter 40 inches tall so the riser wall thickness is 2 inches. Thank you in advance.

Gary B

PPotty1 came up with this mix and has had no signs of failure.

1 gallon of perlite

2 lbs of alu oxide powder

350 ml of sodium silicate

350 ml water

mix all that together you can increase the amounts just keep the ratios the same, takes 6 days to set hard enough to put heat on it then it bakes really hard its very light too.




you can make the sodium silicate by boiling 200 grams caustic,300 grams of silica gel, 500 ml water boil until silica dissolves.

The oxide powder is used for sandblasting quite cheap get the small size grit.

Dale I looked over your suggested recipe. I can source all these materials I think but I am wondering if I will need to put something on my card board molds (sono tubes) this is what contractors in MN pore cement into as a form to get below the frost line then attach porch posts to. I am pretty sure sodium silicate is liquid glass and I am just wondering if I will be able to remove this cardboard form with out destroying the riser. One last question is there a place where you would recommend to buy these materials?? I do have the perlite.

I am betting you can coat it with some sort of release agent, like Vaseline.
This is what ppotty1 did.

also t2h ppotty used a mix of perlight and 1600 Castable Refractory  which is upon the video above

which is this stuff here

http://www.castreekilns.co.uk/dense-castable-189-c.asp

heres some more info garyb

https://woodstoves.forumotion.co.uk/t666-refractory-mixtures

there is a warning with the sodium mix

https://woodstoves.forumotion.co.uk/t577-casting-a-core

Many years ago I read in Fine Home Building about guys spraying a mixture of Diesel fuel and oil on their wood forms as a release agent. They could then reuse the lumber in other parts of the construction. I don't remember the exact formula.

thankyou for that info firedgnr8

http://homeguides.sfgate.com/keep-concrete-sticking-wood-93580.html