Stucco vs. Mortar PLEASE HELP

[ShawnNoffy]

So I hired someone to finish the oven with stucco. He showed up today with 3 bags of mortar mix. Also, he said he is putting paint into the mix to give it the color I want.

Has anyone heard of this? He sounded like he knew what he was talking about but I had to check here.

[BenKeith]

You are doing what I've been researching on doing to mine. My future son in law is also a licensed contractor an I was just talking to him about it. From what I've found, any cement is going to crack over time and if the oven it not under a shelter it's going to start leaking if there is not a special skim coat applied over it that will not crack. The ones we checked on for that was fairly expensive, one being rubber based and considered the best but very expensive since it's not sold in small amounts needed for an oven. The supply house specializing in stucco finishes recommend a synthetic stucco, it will not crack. However, it's a soft outer layer and will puncture if hit very hard with something and poked.
Since at the present time, I have no plans to cover mine, I'm going with the synthetic stucco outer layer.

[SableSprings]

So I hired someone to finish the oven with stucco. He showed up today with 3 bags of mortar mix. Also, he said he is putting paint into the mix to give it the color I want.

Has anyone heard of this? He sounded like he knew what he was talking about but I had to check here.

Yes Shawn, the coloring additive for mortar and cement is sold in both powder and liquid form and has been around for quite a while. The only caveat is that normally you will need to mix several batches to complete the dome. Hence, it's very important to get a consistent mix and amount of the coloring agent so the entire dome has the same shade. I prefer the dry powder because I can evenly mix up all the dry amount of mortar I'll need for the job (+ some extra ) with the coloring powder. Then I take what I need of the dry mix, add water, and apply. I feel my coloring will look better on the overall final coat with this method than mixing the coloring agent into each batch...did I add three cups or four before I took that phone call?

In addition to synthetic stucco as Ben mentioned, there are also additives you can buy for concrete or stucco that provide pretty good waterproofing. Look up Xypex or Kystol additives through the Internet (concrete waterproofing additive). Also as Ben's future son-in-law infers there is no perfect, one-time way to waterproof an oven other that put it under a roof. The old saying is that there are only two kinds of concrete...one that has cracked and the other that will crack. By the way, also look up synthetic stucco on the Internet...some interesting issues.

Post some pictures of the stucco job during the process and when it's completed.

[UtahBeehiver]

Are we talking paint or liquid colorant?

[SableSprings]

Good clarifying question Russell. I couldn't imagine someone using regular paint to color the stucco, so I assumed the person Shawn was hiring knew what he was doing...but you are absolutely correct--never assume

Shawn, please let us know if he just said "paint" because it was easier to say than liquid colorant or coloring additive

[jbez]

You are doing what I've been researching on doing to mine. My future son in law is also a licensed contractor an I was just talking to him about it. From what I've found, any cement is going to crack over time and if the oven it not under a shelter it's going to start leaking if there is not a special skim coat applied over it that will not crack. The ones we checked on for that was fairly expensive, one being rubber based and considered the best but very expensive since it's not sold in small amounts needed for an oven. The supply house specializing in stucco finishes recommend a synthetic stucco, it will not crack. However, it's a soft outer layer and will puncture if hit very hard with something and poked.
Since at the present time, I have no plans to cover mine, I'm going with the synthetic stucco outer layer.

What you discovered in your research is almost exactly my experience. First, my stuccoing skills are very limited. I applied three coats of homebrew stucco over my insulation. Within a year it had cracks large enough that water was finding its way into my oven chamber. Small amounts, but still enough to make any residual ash damp and clumpy. I patched all the cracks with a caulking recommended by the supplier and then applied a coat of acrylic stucco over the existing render. It's been five months and so far, so good. I had to to run a series of curing fires again but the oven is now performing like a champ again.

I can also verify what SS said about inconsistent coloring. My limited skills could NOT produce consistent color batch to batch, hence a blotchy appearance. The Parex product has a wide color pallete and is fairly easy to apply. I used about half of this bucket to cover my oven and, I believe, it cost about $80 at Continental Stucco Supply.

[Gulf]

Traditional stucco starts at the mesh layer to which the scratch coat is applied. Some feel that applying mesh to a dome is too hard to do. For those, the newer stucco mixes have fibers included in the mix. Yes, reinforced concrete, mortar, or stucco will get season cracks for which a flexible finish coat can accommodate. Mesh and/or fibers are considered reinforcement. No reinforcement = gaping cracks. A flexible coat can't accommodate for that. Do one, the other, or build a roof over the oven. just sayin' .