I think this may have been brought up before but here goes anyway. My last few fires I’ve noticed some smokey exhaust smell. I think maybe it smells because I recently cleaned my chimney and pipe and noticed some dust that was sucked in between the pipe joints? I bet this is where the exhaust is leaking out on first light off until a good draft is going. Can someone use that Boss Fire Stop silicone between the joints to form a permanent seal? Seems like it would be less hassle and mess than stove cement.

Whats the temp rating on the silicon? i havent found one yet that has a high enough temp rating to handle those kind of sustained temps.

The highest temp silicone I’ve seen is 650.  You’ll need gasket cement I would imagine.

the 136 firestop standard requires min 1250 degrees the boss 136 is tested to 3000 degrees
Dap 136 2000 degrees

3M Fire block 136 also meets the ASTM E-136 standard which is 1250 degrees

the Boss 136 is listed for furnace use and chimney surrounds Also the Dap product is listed for wood burning stoves.

Rutland 500 degree High Heat Silicon Sealant can only be used when surfaces do not exceed 450 degrees continuously 500 degrees intermittently. Which means it cannot seal single wall wood stove pipes. It may be used to seal pellet stove vents and used for sealing the damper block off plates around the perimeter but not the actual area around the single wall pipe cut out.

So the answer is yes?

Where can you buy this stuff?

Home Crapo sells the 3M version, hardware stores or building supply centers your best bet.
Look in the painting sections where caulking is usually found

Todd - 13 May 2006 11:45 AM

So the answer is yes?

I’d say “NO”.  While the typical temp might be under the 700 degree vaporizaion limit of ALL silicones, if you exceed this under stress conditions, you may not be within the limits of safety.

Anyone have any other ideas for a permament seal on stove pipe?

These 136 standard caulks are more pliable when leaving the tube than refactory cement. They dry hard not pliable like silicone
Dap brand claimes use for sealing fire bricks in wood stoves.,
It will withstand wood stove temps. One can use 2000 degree refactory cement to seal connector pipes as well. The only
difference is the original caulk bead is easier to work with. It is not flexible like the 500 RTV

I purchased some firestop caulk last year. 

So, I started applying it and noticed it was very similar to another product.  Dried hard and brittle.  I realized this stuff IS most likely just stove cement jammed into a caulking tube.  I don’t know what brand I got, I know the tube is yellow and what came out of it was brown.  If you get high-temp firestopping caulk, make sure the color that comes out is black, you wouldn’t want the same stuff I got that’s a medium brown color.  Even if it was stove cement jammed into a caulking tube, being able to use the gun for the application creates a cleaner and tighter application than trying to apply it with your finger.  Do they make empty caulking tubes you can fill yourself?  You’d then be able to put some black stove cement in it, and apply it with the gun for a tight fit and clean application.

I’m not real worried about the color because I want to apply it inside the female pipe, then insert the male end and screw together to make a permanent air tight seal.

Stove cement would work good.  It comes in caulking tubes for easy application.

While I’ve never used Boss-136, I did email the company. Their representative told me that stuff can stand up to wood stove heat and can be used as a stove cement replacement even though it’s sold as a fire stop. All fire stop products are not created equal. There are a couple standards as elk mentioned. The Boss 136 product also remains more pliable and should have better adhesion than stove mortar when dried. Since I haven’t used it, I can’t say if it stays as pliable as standard silicon, but I think elk has used it. Maybe he can say. I can’t find the danged stuff around here!

Short answer: The manufacturer says YES, but it has to be the Boss 136 product. They make a couple different fire stops.