MICORE PROBLEM !

[donatello]

I had installed my new PE insert in November,made a hearth of 1/2" DUROCK + 1/2" MICORE + 1/2" DUROCK + 1/2" marble tile. The extra MICORE I had remaining I installed inside the fireplace (to seal where the damper was) approx.6" above the insert. There is a sheet metal box around the insert that houses the blower (side) and the blower outlet manifold (that directs the heated air). On the top of that sheet metal box, I cut a couple stacks (for the front and back) of (9or 10 pieces) micore 2"x6" to support the larger pieces of MICORE (two pieces mated to fit around the SS.chimney insert) that was sealing the damper area above the insert.
I was in the cellar when one of my Boston Terriers was barking up a storm. I finally decided to go upstairs to see what her problem was... The room was filled with smoke. Upon further investigation (removing the insert surround), I found my MICORE smoking. (No not a cigarette)The MICORE looked like old grey used charcoal brickets! They were now falling apart when I picked them up and into the ash can...
Sooo, MICORE is WONDERFUL for making a hearth. Don't use it as I did, above the insert! I thought it could withstand the heat. Live and learn... I had to open a couple doors and air out the house before the wife and kids get home!

 

[begreen]

Give that dog an extra bone.

 

[DiscoInferno]

I had the (apparently mistaken) impression that micore was essentially the stuff my baffle is made of. But then I'm confused how it could be acceptable for hearths then?

 

[begreen]

Micore is listed not flammable. Melting point 1200 degrees. There is a bit of difference in temperatures between a hot hearth and direct contact with the flue pipe. But it is a little surprising. Donatello, just checking, are you sure this product is micore?

Does anyone have a scrap of micore that they could put a propane torch to as a test?

 

[DiscoInferno]

I think you mean non-flammable; doesn't "inflammable" actually mean the same as "flammable"?

 

[begreen]

Yeah, that always trips me up. I'll edit it to avoid confusion, thanks.

 

[donatello]

Rereading my post I failed to include the following which is important. Approx. an hour before the incident, I had shut the blower off so I could throw in some wood. I forgot to restart the blower. I guess the stove built-up too much heat and couldn't shed it.

 

[jtp10181]

The blowers are optional, everything should work fine and be safe without the blower running.

 

[Bill]

I have some extra Micore from my last install, if you want I can hit a piece with the torch this weekend.

 

[elmoleaf]

Micore 300 is not fireproof. In addition to mineral wool fibers, clay, and perlite, it does contain some cellulose and starch. If you refer to the product's submittal sheet on the USGS site, you'll see that it has a Flame Spread rating of 25, and a Smoke Developed rating of 10 . These are the product's surface burning characteristics, as measured in the test ASTM E84 (a horizontal sample of the product is exposed to a flame for 10 minutes). For comparison, the Flame Spread of a piece of red oak is rated 100 and a piece of inorganic reinforced cement board is rated 0.

Essentially, as you noted, the product may char a bit and smoke, but not actively burn.

 

[donatello]

Here is a picture that shows the 4 stages of MICORE. All the overheated pieces are actually sitting on a fresh piece of MICORE and a small piece of fresh MICORE is on the right. When it gets to stage 4, it is so light and flaky ( it actually almost sounds tasty) it just falls apart into dust...

 

[DriftWood]

Micore 300 submittal sheet from the USGS site,
http://www.acoustics.com/specs/USG_product/usg_spec.pdf#search=’micore