Trouble! Mortar not drying.

[Rickbaro]

Hello all, I’m using an air set fire brick mortar from Acme brick. It comes wet in the bucket, and they recommend that it be watered down to the consistency of heavy cream. I did not go that far, and mixed just enough water into it to make it pliable. However, it has been out for a couple weeks now and it has not cured! Not only that, but it has contracted and shrunk slightly between the bricks. Argh!

So, has anybody else run into this, and is it a fatal problem? I have a feeling I'll be dismantling my first two chains, but thought I'd check first. Plus, if the mortar is the problem, what else is there? This wet is all I could find after a bunch of phone calls in the Dallas/ Ft. Worth area.


Thanks for any advice.

[Neil2]

Has the weather been wet ?

After a week you should protect it from the weather. At some point, you have to cure refractory mortar with direct heat.

[Tscarborough]

What brand is it? Is it Able?

[dmun]

Chronic wet premix problem. I don't know why they even sell that stuff. It will dry, but it may take weeks, and it won't be waterproof then.

What are you supposed to do with mortar the consistency of heavy cream? I think you've been ill advised.

[Tscarborough]

Those are correct instructions for an indoor fireplace where the joints are less than 1/8". For exterior use or joints greater than 1/4", you are operating outside the range of that refractory mortar's performance. Do not blame the product for failing when it is not used within it's design envelope.

Did you tell Acme what you were doing with it?

[Rickbaro]

Well, I did tell the guy at Acme what I was doing, but I 'm not so sure it registered. It's their house brand air-set mortar.

It got to freezing here while the mortar was wet, so I'm sure that didn't help. It has also been rainy, but I've kept plastic over it. We had a warm sunny day and I found that the mortar has hardened a much more than it has in the past, so I'm a little less worried about it.

Are you able to get dry mortar in Austin? I'm heading that way in a couple weeks, and could pick up a bag.

[Tscarborough]

It is Able out of Houston, which is an air set-fire cure, not good for anything over 1/4 to 3/8" or outside, although I used it on all of the inner oven parts of my oven.

The good stuff is probably available in Dallas, and is certainly available in Austin. The guys that host this forum also sell it and are competitive, with freight, to local prices.

[Neil2]

"It got to freezing here while the mortar was wet, so I'm sure that didn't help."

If it froze, that could kill it. Neither portland or refactory mortar can take any freezing when it is curing.