Wrong cement

[Mike1000]

Hi I have made a gym ball oven and I have mixed mortar instead of cement with vermiculite at 2 parts mortar to 5 parts vermiculite. Am I better off starting again or should I wait a week and see if it falls apart. Any suggestions welcome

[Hattori-Hanzo]

Gym ball vermiculite ovens aren't really recommended around here. Let me guess you saw it on youtube? (Us newbies have all been there)

Vermiculite is an insulator and isn't really suitable for the interior of an oven. It is however used on the exterior of a brick or cast oven to insulate it.

Do a search for gym ball oven or vermiculite pizza oven on this forum to find out more info as to why they are not recommended.

Also do a search on "Casting" a oven using castable refractory cement or "home brew" which is a much more suitable route to take.

If you're at the early stages of the build it's worth stopping and researching before continuing.

[Gulf]

I have mixed mortar instead of cement with vermiculite at 2 parts mortar to 5 parts vermiculite

I'm not a fan by any stretch of the gym ball method. But, my advice is to let it cure and dry, then fire it up. Who knows if it will work. You recipe may be better than the original bad recipe.

But first lets find out what your recipe actually is?. You said "mortar". Did you mean "masonry cement" ? If so, was it Type S or Type N. Type N is 50 % portland / 50% hydrated lime or the equivelant., Type S has a little more portland in the mix. "Mortar" on the other hand is a blend of masonry sand and masonry cement. If you used mortar, then your recipe is a litte lean from the original mix they advise on the utoob reruns. If you actually used masonry cement in the recipe, you aint really all that far off.

Regardless of what you used. It would be great to get some feed back on how well it performs.