Distaster with my motar

[Robert Collins]

Last summer I began building my oven, I found Refractory bricks and Refractory cement called morcoset by Missori Refractories at 40$ a 3 gallon bucket I think i bought 7. Well things went well the weather was great for weeks and i was 3/4 done . then a prity good rain storm came and washes out all my mortar.I was devistated . I had no clue it was not cured.
its 6 months later now ive decided to try agin. my boys cleaned off the bricks it came off like frosting with alot of sand, like sand castels you build at the beach.
I need to get the rite motar. I cant find it on the FB site. can some one help. Im in tennessee

[Faith In Virginia]

I don't know what that is that you used. I used No. 36 from Harbison Walker you might want to call them and ask the difference between what you used to what they have. Here is the closest one to you that I could find (Harbison-Walker Refractories
1201 Brock Industrial Drive, Birmingham, (205) 788-1685 )

It might be a good place to start. I don't think my No. 36 ever really cures and I don't think I want to get it wet either but those guys know their product.

[Tscarborough]

The type of mortar you used is a heat-set, water soluble mortar. It is designed for very narrow joints only, and that is more of an issue then being water soluble, since your oven when complete should never get wet. You need to use a material like Heat Stop, or home brew that is a high-build mortar, since the joints in a Pompeii oven are relatively wide.

Clean them off and start over, and keep it covered no matter what type mortar you use.

[GianniFocaccia]

Robert,
I used Sairbond refractory mortar that I got from Harbison Walker to build a firepit and all was well until it got some rain on it. When touched, the mortar crumbled like dried popcorn. I had no idea it was water soluable. I am currently building a 39" Pompeii oven using fine (#12) silica sand in the traditional homebrew mortar. It is great to work with and really inexpensive.

[dmun]

Yeah, we've had so many people have problems with wet pre-mix refractory mortar, with exactly the results you had. It's for a completely different application than ours, (as tscarborough said), and it's really expensive. I used heatstop50, which cracked abundantly, and if I built another oven I would go the homebrew route.

[stonylake]

I used a pre-mix called Darby 3000 and loved it. If i had an extra 15 minutes, i could set 3 or 4 bricks and just close the bucket back up... no mixing, no cleanup, and no wasted mortar. i did however have a 10'X10' square of EPDM roofing that i used to keep the oven covered at all times, and i parged the oven with home brew...

[WoodchuckDad]

Heatstop 50. Powdered in 50 lb bags. dried hard as stone.