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blacknoir 07-06-2009 06:52 PM

Mortar not sticking
I hate to ask this but here goes. Some of my bricks have a tendency to come undone after a day.. an example is my arch.. it looked good but I bumped it while working and it shifted. I looked closer and there were a few connections that weren't sticking. It's an arch so it stays up but I'd prefer it stick together more.. I've also had bricks come loose on me... Do I just need to be patient and wait a few more days for them to firm up or are the ruined now that they've come loose? I've slabbed on more mortar where I've seen some come loose but I worry about that arch.

I've worked with thinset before and that stuff stays stuck.. but that's inside where the temp and moisture is fairly even.

The first time this happened was the day after I had setup my soldiers. I bumped one while setting up to do the next row and a whole section of soldiers moved. The section seemed rock solid but it still came away cleanly between 2 bricks. I checked the rest of the soldiers and there were a few breaks like this. That time I shaved off the old mortar and put new mortar on. I really don't want to have to rebuild the arch since I've already started putting chains against it.

dmun 07-06-2009 07:40 PM

Re: Mortar not sticking
Mortar doesn't reach anything like full strength for a week or so. Keep all new masonry moist, and avoid shocks and stress for a week, and you should be all right.

You wet your brick before laying them, right? Dry bricks can cause the non-adhesion you're talking about.

blacknoir 07-06-2009 08:21 PM

Re: Mortar not sticking
Oh yeah, my bricks sit in water for at least over night.. I also wet any dry areas before adding bricks to them. I'll just leave them and hope for the best.

timo 07-07-2009 07:34 AM

Re: Mortar not sticking
I am working with the home brew mortar and can say that it takes about 4 days to get hard.

On the other hand, between the sun and air, it sets in a few minutes. I am constantly soaking bricks and spraying the next course for the next brick.

What mortar are you using?

pizza_bob 08-06-2009 05:48 PM

Re: Mortar not sticking
I called the manufacturer of Heatstop 50, which is what I am using for my oven. I asked them if the firebricks should be soaked in water prior to mortaring. They said absolutely not! I have heard so many people say they soak the bricks but is this really the correct method? I have been going somewhere down the middle...I keep a spray bottle on hand and lightly mist the brick surfaces that will be getting mortared. The bricks seem to set quickly so I have to hurry to get them properly aligned.

Will mortar stick to a brick that has a thin coat of mortar on it? My soldiers have a 20 degree angle cut on them and when I mortared them together I left a very thin coat of mortar on the 20 degre face. Now I'm concerned the second course will not adhere properly to this...


Les 08-06-2009 05:57 PM

Re: Mortar not sticking
If the mortar has a good bond - absolutly. BTW, I never soaked any of my bricks either and have had zero problems.


dmun 08-06-2009 07:26 PM

Re: Mortar not sticking
Firebricks are pretty porous: if they are bone dry, they will suck the water out of the mortar, and endanger the bond: mortars need to keep wet to set properly.

My experience with heat stop leads me to believe it will stick to anything. I don't think an existing layer of mortar will be a problem at all.

diy 08-07-2009 07:38 AM

Re: Mortar not sticking
For application with Fire bricks you must use proper refractory cement. For outdoor application Heatproof Screed is the correct material to use.

enasfournos 08-07-2009 08:04 PM

Re: Mortar not sticking
Have the same problem using fire clay,does any one know the correct ratio to mix cement and fire clay?
Have mixed 1:1 no luck, can't get it to stick to fire bricks,also tryed 2:1 no luck.if anyone knows the receipe please reply.

FIREANDFLAMES 08-08-2009 04:53 PM

Re: Mortar not sticking
When i build my oven i had a bucket of water and soaked the bricks for mabye 5 min. And a year later no cracks or nothin!

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