Should I scrape the mortar on the inside before it falls?

I noticed when I was cleaning that there were little chucks of mortar and when I looked up I could see pieces falling off. I pulled a few down but there are still loose sections, should I bang/scrape these down?

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No! (but a qualified “no”)

In general, do not scrape or bang inside the oven. One of those chunks could pull out a whole joint with it, and then you have a bigger repair job. That’s problematic because of the risk that the repair job itself could fail. (There are special compounds that can be used for mortar repair; search these forums.)

If you are concerned that some of what looks like “flash” may fall into your food, try a wire brush or your mason’s coarse-bristled brush that is one of the recommended tools. But you must resist the temptation to start picking at the joints, testing them, and so on. Just brush gently and remember that firebrick is fragile and a little brittle.

Do not approach this with a lot of energy, or you will cause some damage that you are sure to regret.

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on that topic - I’m a little worried that after I removed the foam there’s areas that have gaps/cracks between the brick where’s there isn’t mortar. Will this be a problem structurally?

Hi Mark, and welcome to the Brickwood forum!

Gaps won’t be a huge problem structurally, unless of course they are holes that go right through the joint. The arch structure tends to keep order.

If they are very concerning to you, you can use a high temperature silicone mortar patch (search these forums for a couple of threads on the topic). It’s applied like caulk, and it cures with heat, so don’t use it outside your oven space.

But again, gaps that go an inch or so into the joint are not a major issue.

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Thats great info @bikerbudmatt - thanks for that. Would I want to ‘smooth out the mortar/caulk’ after applying to even it out in between the cracks - or naturally let it get in the spaces?

Here is my “now it’s morning and I’ve had my coffee” reply.

The good news is that you can still use high-temp mortar to fix those cracks as long as you have not yet fired up your oven. This is preferable to using the silicone mortar patch.

Here is a FAQ on the subject:
Should I fill in the voids or leave them alone?

As you’ll see, it all depends on whether your oven has had a fire in it yet.

Good luck, Mark, and keep us posted!

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very good - thanks for the reply (after coffee lol).
I haven’t fired up yet so I’ll fill the cracks and let it sit for a few days before firing up the oven.

Thx again for advice and help. can’t wait!