Aldona Guenter : Ask 10 people
get 8 different answers, and the two that agree will be only part right ! Fire clay is not called fire clay because it handles high temperatures
the best, rather it is because it expands when heated, and contracts the least amount when cooled !
Usually Refractory cement is called 'hard' which means it expands and contracts little, but this can cause the brick it is bound to to chip crack, or break in half !
Here is where it gets tricky, Some people dip their bricks in water for about a 5 sec. count and then dip them in a clay slip, and using the clay slip as a sealer between
clean sharp bricks, lay up their burn tunnel with out any Refractory cement to mortar at all. once ' layed up' this method seals out air gaps and is quite effective in building
both the Burn Tunnel and Heat Riser during your outdoor experimentation phase !
During the actual indoor build, you can still build a Burn Tunnel this way as it will be wrapped in insulation and protected from being jared by the setting of the barrel over
its top !
However, the Heat Riser, which is subject to being jarred or moved by the Placement of the Barrel needs ether a clay and sand mortar to lock the bricks of the Heat Riser
into one solid unit , or the use or a Refractory Cement! - Here again you may find that the Clay and Sand Mortar is more forgiving than the Refractory Cement
The use of Sodium Silicate is an option, rather than relying on a clay slip and Perlite mixture, I have been told that the fine dust of the perlite needs to be screened out
- otherwise the fine dust combines with the water glass and becomes very much like glue !
Lime water retards the ignition point of fire, making it safe to hang heat lamps in close proximity, water glass will allow a product that is very much like rice cakes to stick
to itself, and create a mass of Perlite that will be more insulating, and more highly refractory (two separate things ) than just a mixture of the cheaper clay slip and Perlite !
If Sodium Silicate with Perlite is better than Clay Slip and Perlite, (probably, but I have not seen figures !) Then because the vermiculite will need to take up more Clay Slip
to bind to itself, it is inferior to ether of the perlite mixtures !
, also sold under the name Roxul, (SP) is cheaper and possibly superior to ether perlite, or vermiculite, it is generally held in place with a wrap of chicken
does take a certain amount of faith to believe that the chicken wire will last as long as the barrel, so far @ at least 4 + years, it seems likely to do so !
I blame the advertising
agency connected with the selling of a specific type of 'pink' fiberglass with convincing must of the people in the U.S. that if it comes as a 'Batt' or
on a 'roll', that the product is fiberglass, in fact you do not want the fiber glass you want only the 'rock wool' Good luck Big AL !