Big or small vermiculite?

[Mike D]

I went to HD to see what they had in vermiculite. They had big bags of a small type or fine grade of vermiculite. It looked different than what I expected. I tried looking around the threads, but didn't see anything about the size of vermiculite. Am I looking for the larger size (to get that oatmeal mix) or will this finer grade work the same.

Mike

[dmun]

Re: Big or small vermiculite?

HD had 4 cu ft bags of vermiculite? This is news.

The small stuff will work as well as the large particles. The only thing we've been warned off from is the silicone treated vermiculite, and at least one user has used this successfully.

[Mike D]

Re: Big or small vermiculite?

Thanks dmun-

I think they were 2 cu ft (at $17), They had perlite as well, in the garden center. Is there a difference in using perlite or vermiculite. Any advantages of one over the other (ease of mixing, insulation value)?
Thanks-
Mike

[david s]

Re: Big or small vermiculite?

Perlite is a marginally better insulator but probably marginally more expensive. I prefer vermiculite because it does not break down on mixing as much as perlite so you don't lose volume. I found perlite also contains a proporttion of dust that is irritating when inhaled. The perlite, that I've used also tends to float in the mix making it more difficult to get a constant mix. I'm sure that both materials vary depending on their source, but these are the characteristics I've encountered.
Dave

[mn8tr]

Re: Big or small vermiculite?

I used standard vermiculite from the garden store. I have had my oven up to full operating temp several times and have never felt the slightest bit of warmth. After 3 months there are no visible cracks or weak spots. I used around a 70/30 mix concrete/vermiculite (give or take). So far so good.