Stucco / Mortar Shell Question


I am preparing to wrap my oven in the ceramic blanket and do the first half inch layer of mortar. I have two questions about the procedure:

  1. Since I will be using mortar, should it be a little thinner than normal mortar to make it easier to smooth over the blanket and chicken wire?

  2. Once I begin applying a shell layer do I need to finish the layer in one session? If so how much time should I set aside for applying a layer of mortar?

Thanks very much.

Hi Greg,

The chicken wire matrix will take the mortar just fine. Mix it as recommended. And yes, 1 coat in one session. The first coat will look a little scruffy and some wire may stick out of it, but don’t try to make it pretty. It’s the second coat you want to take some more time with.

It goes on fairly quickly, and with the second coat any small imperfections get smoothed out when you use the wet sponge on it.

Thanks very much Matt. The directions call for three 80 lb bags of mortar, so I should plan on mixing 1.5 bags for the first layer and the same for the second. Are there any tips for keeping the thickness of each layer at half an inch? Maybe toothpicks stuck into the blanket? Sorry, I’ve never applied mortar this way before and I am trying to avoid a mess.

Thanks again!

Toothpicks would work if you want. Everyone’s different but honestly I wouldn’t worry too much about it. Stucco is one of those things you get a feel for.

If you do toothpicks, have them out a full inch from the insulation, and do half a toothpick for the first coat and bury it for the second coat. They won’t do any harm. Try not to cover your work surface in toothpicks! Just a few so you can stay oriented as you complete each coat. (And again, that first coat is going to look a little rough and don’t worry about it.)

Thanks Matt, your advice is very timely and helpful. I probably am over thinking it.

I finished the back of the oven, the end of the firebrick phase. :slightly_smiling_face:


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You have a great barrel there! The beautiful thing about this is you’ve no doubt discovered how difficult it is to get a perfect curve cut into those end bricks—even though yours are excellent. The exterior is completely hidden by insulation, wire matrix, and stucco, so it’s good you’ve taken photos now because you’ll never see this view of your oven again. :wink:

I’m sure you’ll have no trouble with the stucco, and thanks for keeping us “in” on your build, Greg!

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Thanks Matt, your encouragement is helping me make it closer to the finish line! I completed the first coat of mortar. You were right, it wasn’t too bad. It looks rough, hopefully the second coat will look much better.

Yes! That looks exactly as it should for a first coat. You’ll find the wet sponge is truly your friend for the second coat. It will also raise the sand for a proper sandy stucco finish.