39 inch Corner Build

[david s]

It will exceed 500 F there for sure. Flames often lick around that point on my oven. I use vermicrete there. If concerned about that not being adequate use some calcium aluminate cement to mix with the vermiculite or source a product that can handle the heat. The highest rated silicon I could find is Permatex Ultra Copper @ 700 F intermittent.

[Mullins]

Just to clarify the pictures I see in post 154 are what Gulf has in his screen print in post 161? on both the iPad and the laptop!\\

[JRPizza]

I just took this capture of his post 161???

[Mullins]

Something very odd going on then. The number of pictures in his screen print and your screen print are different! Maybe delete all cookies and clear your cache, and then look at his post again? It's possible your computer is picking up something from your cache instead of reloading the page (that could make sense for the difference pics you see,but still doesn't explain different pics in the screen prints!)

These are the 2 pics that I see as pics one and two. A regular arch and a double "S" arch

[JRPizza]

Maybe Gulf had it right - poltergeists!

[RandyJ]

Hi Jr you will want something better than 500 degrees. I think the stuff I used was called something like fiberfrax. I believe it was rated to 2800 degrees. Good luck.

Randy

[JRPizza]

Yeah, I don't know what I was thinking - maybe 500C?

[RandyJ]

500 C might be ok but that is still only 932F. You probably won't get that hot there but it could get close on the surface if flames are present on the surface there. Just a thought.

Randy

[david s]

It will exceed 500 F there for sure. Flames often lick around that point on my oven. I use vermicrete there. If concerned about that not being adequate use some calcium aluminate cement to mix with the vermiculite or source a product that can handle the heat. The highest rated silicon I could find is Permatex Ultra Copper @ 700 F intermittent.

If you've found a high temp silicon that can withstand 500C, let us know, I want some.

[UtahBeehiver]

I used Uni-Extreme made by McGill Airseal it is good to 2400 F and environmentally friendly. I is NOT silicon based and sets up firm. Used it to seal in my CF rope on my arch heat break.

[JRPizza]

Russell, did you buy the Uni-Extreme online? I found an online source for the stuff RandyJ used, but could not find a source for your produce. Plenty of info from the McGill website but did not see any pricing.

[UtahBeehiver]

JR,

I found it at a surplus store that I frequent every week. I bought all they had for a buck a tube and sold the extra to other members on the forum for cost plus shipping. Unfortunately I sold them all. So short answer, you may have to call them and see how much. There is a another modeable caulk called kawool cf caulk that is good to 2000 f. I have not used it personally but others have. I think it is about $20 a tube.

[JRPizza]

Wow, a dollar a tube was quite the score. I was able to search, now that I have the brand names (thanks to all) and found both Kawool and Inswool moldable for about $15 a tube. I also found some for $42.73, do I guess it pays to shop around

[JRPizza]

I have not made any progress on my oven lately, but I have been thinking about it alot.
Have a question for the experts though on my portland cement. I bought my 80lb bag back in September, and although it has been stored in my garage (unheated) I think it might be picking up moisture from our soggy Seattle air. I noticed the sides were getting a little "stiff" (powder along the edge starting to harden a little) and was wondering if I needed to get some fresh stuff. I would hate to have to find a way to dispose of 50+ pounds of cement, but also don't want to use something on my vent arch that is going to have compromised properties.

[Gulf]

This question comes up from time to time. You will probably get the "best practice" reply which is to chunk it because Portland cement is cheap. And, that is good answer. But, I have no problems with using Portland cement that is just starting to clump as you described. Take some of the clumps and crush them in your hand. If they turn to powder easily, it is still good. You can buy a little more time for the powder in the middle if you transfer it to a 5 gallon bucket with a lid.