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rbigante 10-09-2008 06:18 PM

Vermiculite Advise Needed
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I picked up a couple bags of vermiculite today from a local pool supply place. I called the manufacturer/distributor whom is also kind of local and found that I did buy pure vermiculite with nothing added to it. It was $18 for a 4 cubic foot bag. My question is regarding the size. Is what I bought ok????? Please check out the pics attached which hopefully depict the size. I wanted to pure my insulating hearth this weekend but don't want to use the incorrect material. BTW, this site is awesome and all the advise I've received to date has been accurate and greatly appreciated. Thanks, Rino

Wiley 10-09-2008 10:45 PM

Re: Vermiculite Advise Needed
Looks like the same size I used. I used cvduke's technique and managed to get a nice 9-10 to 1 ratio (vermiculite to cement) mix that set up with the consistancy of cork. Check out the archives to get his technique of adding the vermiculite to a water cement mix, for a pour it worked easily but would be harder to form up over the dome if one needed it more the consistancy of cottage cheese.

Dutchoven 10-10-2008 04:47 AM

Re: Vermiculite Advise Needed
It will be fine...I found the coarser grade to be the best for the insulating layer of the hearth floor but really any grade of vermic will long as it is just vermiculite which is what you have...have fun and good luck

egalecki 10-10-2008 07:20 AM

Re: Vermiculite Advise Needed
Your vermiculite looks like mine did. I used the cvdukes method too- but I had to scale the recipe down a bit. I couldn't mix that much at once! I did use a bit more portland in the mix for the dome covering, but not a lot- maybe 8 to 1 instead of 10 to 1. It just takes a lot of patience to get it on the dome. Kind of like a big sand castle with crumblier sand.

It is a whole lot easier for me to mix the portland with water first and add it to the vermiculite. I got fewer lumps that way.

rbigante 10-10-2008 12:50 PM

Re: Vermiculite Advise Needed
I found cvduke's post and I'll give it a try I think. thanks everyone

rbigante 10-10-2008 04:30 PM

Re: Vermiculite Advise Needed

I plan on mixing about 4 cubic feet of verm at a time. I can figure out pretty easily the amount of portland cement needed for a 5/6:1 ratio, but am unsure as to the amount of water to use to suspend the portland. Can you please explain?

What was the ratio you used for the insulation hearth?

THanks, Rino

egalecki 10-10-2008 06:51 PM

Re: Vermiculite Advise Needed
I used 5 gallon buckets- put the amount of portland you want to use in the bucket, put in enough water to suspend it all, and mix (if you use a heavy duty drill you can use a mortar paddle). You might want to rethink the 4 cubic feet at a time thing. If you're using a regular wheelbarrow to mix in, it won't all fit.

I did about 4 five gallon buckets full at a time, with a corresponding amount of portland and water. That much fits in the wheelbarrow just fine. I tried to use a 10 to 1 ratio on my hearth. As I recall, I didn't need a whole 4 cf bag for my hearth, but I formed mine up and it's only as big as my oven. I could also mix up the portland by hand that way. I do have a huge drill, but it's usually at a job site...

Once your slurry is in the vermiculite, you can add water as necessary, stirring with your hoe, to get a good consistency.

Les 10-10-2008 07:34 PM

Re: Vermiculite Advise Needed
To add to what Elizabeth said - I mixed in enough water to where it had the consistency of oatmeal. The ratio I used was 5/1. When I used it on my flue, I made it real wet so it would reach the bottom of the cavity. It seemed to set pretty well. At the end of the day, it's all going to dry out and you will be fine.


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