cadenrank Posted January 21 Report Share Posted January 21 So while working on one of my kilns, the fiber gasket that sits between the plenum cup and kiln got damaged. I ordered a new one, and was advised to use any silicone adhesive between the cup and gasket. All of this went without issue, however, 48 hours later, the silicone has yet to cure at all. I read the tube, says to check expiration if it doesn’t cure, sure enough it’s years expired. I don’t have any concerns about getting the uncured silicone off of the plenum cup, but not sure how I’m going to get it off of the gasket. So my problem, do I need to get all of it off the gasket? Both from a curing standpoint for the new silicone and from a firing standpoint (thinking like, uncured silicone getting hot or vaporizing or something from the heat)? or should I just get a new gasket on the way? Quote Link to comment Share on other sites More sharing options...
Hyn Patty Posted January 21 Report Share Posted January 21 (edited) You can get any platinum silicone adhesive at your local hardware store in the wood stove section - gaskets too that you can then trim down to fit your kiln if the thickness is right for what you need. You'll need it to be platinum silicone if it is a location that gets hot at all as platinum based silicone is good up to 600 degrees if I recall correctly. If the area doesn't get much heat and is far enough from the kiln, then an ordinary, cheaper silicone will work just fine. I'd say you'll probably want to replace the gasket, yes - but keep reading. Any uncured silicone will make it very difficult for new silicone to adhere. BUT with that said, if you are inserting the gasket into a position where it will be wedged firmly into place and can't possibly fall out (not a door seal for example where you need to constantly be able to open it) then I'd just try reusing the old gasket first and not worry about it. Any residue of uncured silicone should not be an issue with firing the kiln and heating it up if you used the right kind of silicone for however much heat is generated in that particular location. Edited January 21 by Hyn Patty Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 21 Report Share Posted January 21 (edited) 4 hours ago, cadenrank said: So my problem, do I need to get all of it off the gasket? Both from a curing standpoint for the new silicone and from a firing standpoint (thinking like, uncured silicone getting hot or vaporizing or something from the heat)? Generally rubbing alcohol or mineral spirits are adequate to clean up uncured silicone caulk. Final clean with alcohol usually removes most oil residue and also not likely to harm whatever gasket material is in use. The service temp on high temperature silicone caulk (the red stuff) is generally up to 650f. It is commonly used on gas combustion products that typically top out about 500f. Kiln shells can meet or exceed this. I would not suggest anything rated lower for this use though, most ordinary silicone is rated up to 400f Edited January 21 by Bill Kielb Hyn Patty and Rae Reich 2 Quote Link to comment Share on other sites More sharing options...
cadenrank Posted January 21 Author Report Share Posted January 21 (edited) @Bill Kielb and @Hyn Patty Thank you guys for the information. The adhesive that all of the ceramic supply stores sell that is described to pair with the Skutt gasket is Dow Corning 732, which, according to everything I can find says "cured material stays flexible for continuous use from -76 to 350°F (-60 to 177°C) and up to 400°F (204° C) for intermittent use". Struggling to find any other information in the SDS, not relative to staying flexible, but I haven't found anything else to suggest it's rated to 600. I see a brand called Imperial that the hardware store sells that is rated for 600°f. I'm sure this one would probably be better for the application, but I'm wondering why most suppliers sell one for the gasket that's only rated for 400. I'm going to just order a new gasket, I don't think there's any way I'd be able to get all of the silicone off of the one that didn't cure. The plenum cup I think I can get it off of but the fiber gasket probably not. Edited January 21 by cadenrank Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 21 Report Share Posted January 21 (edited) Common at big box stores - pretty common use in condensing furnaces and boilers. Up to 650f is what I see mostly. https://www.homedepot.com/p/RectorSeal-Hi-Temp-Red-Silicone-Caulk-57500/202809239 https://images.thdstatic.com/catalog/pdfImages/a0/a0b46b08-2550-4bd5-acd8-38b1768a8217.pdf If it’s uncured silicone you likely can remove fairly completely with most solvents, just like cleaning up after application. I assume the gasket is high temp but not quite enough to infill the gap at the kiln so it’s supplemented with silicone. “I'm wondering why most suppliers sell one for the gasket that's only rated for 400.” 600 is most definitely better than 400 but it’s at the bottom of the kiln and the pickup cup brings in outside air adjacent to this joint so this connection is not super hermetic really. What lifespan are they shooting for - who knows. Edited January 21 by Bill Kielb cadenrank and Rae Reich 2 Quote Link to comment Share on other sites More sharing options...
neilestrick Posted January 21 Report Share Posted January 21 I would just leave the stuff on there and put it up under the kiln. It's really just there to hold the gasket in place while placing the cup. Once it's in place the gasket won't move. The heat of the kiln will likely dry it out over time, but even if it doesn't it shouldn't affect anything. cadenrank and Rae Reich 2 Quote Link to comment Share on other sites More sharing options...
Mark C. Posted January 21 Report Share Posted January 21 I'm will Neil on the fix Next time you need silicone use the hi-temp wood stove gasket type-its got a very hi temp rating not 350 which is more like baking cookies Quote Link to comment Share on other sites More sharing options...
Rae Reich Posted January 22 Report Share Posted January 22 I think I got my red silicone at the auto parts store cadenrank and Bill Kielb 2 Quote Link to comment Share on other sites More sharing options...
cadenrank Posted January 22 Author Report Share Posted January 22 (edited) As always, and again, thank you everyone for the responses. @neilestrick I was thinking about trying it. This last maintenance project has taken this kiln out of service since New Year's (mostly just waiting for parts), so the thought of just firing it and just keeping an eye on it and seeing what happened after crossed my mind, but I already had got the old one off, and got the plenum cup clean. I could still put the old one back on (It still has the uncured silicone all over it) but I already ordered a new gasket. I might put it back on just to bisque while I'm waiting for the new one and then clean the plenum cup again later if it doesn't cure still after firing. @Rae Reich I saw that when I was googling it. I found a JB Weld 100% Red silicone one that's rated for 650 that's available at an auto parts store nearby, so I'm probably going to go that route when the new one comes. Edited January 22 by cadenrank Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.