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AnthonyW 02-28-2011 06:48 AM

The right mortar for the job?
Hello - I am new here and new to oven building. I am planning to build my first oven this spring and I have been refining plans and gathering materials since October. I have been reading a lot in this forum, and I'm so glad we have a place to get together and share ideas. I don't think I would be brave enough to attempt this project without this forum to provide such good information.

I have a question about some mortar I picked up at a block plant. They had Adhesive Mortar made by FireRock. I think it's for installing FireRock brand ovens. I bought a couple bags because it was cheaper than the other mortar (refractory cement) that I had previously purchased and I knew it was rated for high temps. But now I realize it might not work for this application.

Is anyone familiar with FireRock brand mortar, and will it work for building a brick oven?


Lburou 02-28-2011 07:07 PM

Re: The right mortar for the job?
The most frequently mentioned mortar is the recipe known as "home brew' here on the website. You may want to consider using it. :)


Originally Posted by James
From the pompeii oven plans V2.0
Here is the recipe for fire clay mortar, where you measure by volume (use a bucket or shovel to measure):

1 part portland
3 parts sand
1 part lime
1 part fire clay

In between Refrax and fire clay/Portland cement mortar, you can make your own aluminate mortar. It is hard to work with, as calcium aluminate can be challenging. If you get the mix, or water wrong, it won't set correctly. It partially sets very quickly, and you cannot re-hydrate it, so you have to mix it and use it in small batches. Still, if you are trying to save money and want/need the heat resilience, heat conductivity and longevity of a true aluminate mortar, it works.

1 part calcium aluminate
3 parts sand
1 part lime
1 part fire clay

nissanneill 03-01-2011 02:17 AM

Re: The right mortar for the job?
there is no choice, as far as I'm concerned, there is only Home brew!
All others are expensive, hard to get and often crack considerably when used.


AnthonyW 03-01-2011 06:13 AM

Re: The right mortar for the job?
Thank you for the advise. I hadn't considered the Home Brew. I think I will experiment with small batches of each product and see what works best for me. I've got time until the thaw!


GianniFocaccia 03-01-2011 08:31 AM

Re: The right mortar for the job?
I took a look at the Firerock website and they offer outdoor firepits as well as ovens. Because firepits are exposed to the elements (ie: rain), I would guess that the Firerock mortar would be suitable for your oven build. I bought some refractory mortar from a national refractory supplier and built a firepit with it. The joints initially dried hard as rock but when the rain hit it the mortar crumbled like dry oatmeal. I'm very pleased that I didn't use it on my oven.

AnthonyW 03-13-2011 01:06 PM

Re: The right mortar for the job?
1 Attachment(s)
I have some news on the potential of the FireRock mortar that I found. I mixed up a small batch and mortared two firebrick pieces together. I let them dry/cure for one week. I then set them in a bucket of water for two weeks to see how the mortar would hold up. I was suprised to find that the mortar seems to be unchanged. It did not sluff of or crumble. When I tried to pry the bricks apart (just with my hands, not using any tools) I couldn't get them to move.

I am not endorsing this product - I just ended up with some on an impulse buy and I'm happy to see that there may be some potential to use it as oven mortar.

The precautions listed on the bag say that the product contains some portland cement and crystalline silica. I certainly don't know enough about this (I still need to read the primer) but is portland cement the primary waterproof ingredient in mortar?

Thanks again for all the responses. This is a great forum.

Spring is almost here - oven construction is around the corner!


tferin 08-29-2011 11:23 AM

Re: The right mortar for the job?
Anthony, I actually just bought two of these bags here in DSM at a local brick yard and I was wondering if you have moved forward with using this product. I have my floor set and I am ready to begin my first ring.

A bunch of folks posting have high praise for the Home Brew but if I can buy it all in one bag premixed for less than $1/lb it seems like a good deal to me.

Overall just curious if you ended up moving forward with this material and if so how well did it preform for you? or didn't?

Thanks for your posting.

AnthonyW 08-29-2011 12:12 PM

Re: The right mortar for the job?
I bought 4 bags (100 lbs) of the FireRock mortar at Glen-Gery Brick in Des Moines. I already had a 75 pound bag of refractory cement. I ended up using the FireRock for the dome construction and using the refractory cememt as a skim coat over the completed dome. Just by looking at the two products, the refractory cememt looked like it contained more silica.

I completed the project in mid May, and have used it almost every weekend (sometimes Saturday and Sunday) and a few weekdays. I am very happy with the results. The oven takes about 3 hours to bring to cooking temp and I can 7 or 8 pizzas (one at a time since it's a relatively small oven - 27 inch inside diameter) before I see a noticable cooling of the oven. This means that it takes a couple minutes more to cook the 8th through 12th pizzas.

Visual inspection of the inside of the dome shows no slumping or cracking of the mortar. BUT, ask again in 2 years and we'll see how it lasts! So far I am happy with the product, and the price was very reasonable.

One unrelated suggestion would be to buy a tile saw and a cheap grinder with a masonry blade. I didn't have the grinder until the dome was completed, and I realized (too late) that I could have easily beveled the bricks to fit together better, using less mortar.

I hope this helps!


tferin 08-29-2011 12:20 PM

Re: The right mortar for the job?
Anthony, this is a huge help and I am planning on moving forward with this Fire Rock mortar from Glen Gery. It seems like a very good product and at the price very hard to beat.

I do have a wet saw that I got from Harbor Freight, one of the best investments I could have made for this project. The grinder so far has come in handy but as walls start to take shape I am sure I will be relying on this more and more.

Do you have any pics posted of your build? I am planing on posting some once I am a bit further along.

Thanks again for your help on this issue. Great Forum for Sure.


AnthonyW 08-29-2011 01:36 PM

Re: The right mortar for the job?

I posted one picture of the finished oven:

PhotoPlog - Finished Ovens

It's nothing fancy, but it works - and that's all that counts!

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