Sorry - another Vermiculite Question

[Frances]

When I did my vermiculite layer, I got worried because mine was very coarse and everyone was using fine grain stuff... maybe its another of those things where it doesn't really matter much either way so long as you get the hydration and concrete proportion right?

[thebadger]

That's kind of my issue.

What I have is very fine - almost like sand. To be on the safe side I'll probably get the Isol board but still want to pour a smaller insulated hearth...

My main question is should the "fine" stuff be okay? 5 to 1 ratio as well?

Thanks
Dick

PS - George - I did see your response but want to get a consensus. This is something I can't change once my floor is down...

[gjbingham]

Otter,
You can't hurt my feelings. I would do the same! I thought you said you could take it back and exchange it?

[thebadger]

George,

Thanks!

I can - and I think I will take it back for the perlite... I'll probably put down a 3 1/2 inch layer (extra height and insulation) and then 2 inches of Iso board on top... That should bring my oven height to ~43".

Thanks
Dick

[gjbingham]

I like that! Lots of insulation under the floor. Great idea!

[thebadger]

Done,

Traded 4 bags of Vermiculite for Perlite.

Is the ration 5 to 1 or 6 to 1? My Pompeii version 1.2 says 5:1 but I see postings that say 6:1? Is it a big difference?

Thanks
Dick

[gjbingham]

Everyone chooses their own path. I did 5 to 1. 6 to 1 gives it higher insulative properties, at least I believe. I also believe that it makes it weaker due to the reduced amount of cement in the mix. People do what they think will be best in their own ovens. I followed the plans on that one.