I found 4 types of clay please help me choose the right one for the 3:1:1:1 formula.

[ZIYAD]

Hello everyone, I would like to thank all the forum participants for sharing valuable information from their experiences and expertise it made me excited to build my own pizza oven. I started looking for the materials needed for the 3:1:1:1 formula.

For cement i found ordinary Portland cement

For lime i found hydrated lime @ 90% purity

For silica sand i found it @ 98% purity. From what i understand it should be washed sand and for mortar i should use fine sand for casting should be coarse right?

For pp fibers I found it @ 12 mm Length and a thickness of 18 μm or 34 μm

My problem is with the clay, The supplier for clay have 4 types Red Clay, Kaolin, Washed Kaolin ( Low in iron ) and the fourth type is only labeled as clay, The all have different composition for example low or High iron.

I told him I need a clay that is called ( Fire Clay ) he did not know it, So I got the composition of each type of clay from them, I ask anyone who understands clay to please see the attached pictures and tell me which one of them is considered fire clay. Thank you all for your help much appreciated.

[david s]

For the temperature we fire our ovens to, pretty much any clay should be suitable, the iron content only becomes a problem for temperatures over double that to which we fire. But go for the clay which has the least shrinkage because that can be a problem as the brew dries and there’s a high clay content in the mix. Better and probably cheaper if you can source bricklayers clay from their suppliers.

[ZIYAD]

Dear David, Thank you for your response. I went to all the brick shops in my city and in two other cities, everyone says that they have no clay and that they have a problem in the supply chain like the rest of the world because of the disease.

The only source who has clay at this time is the owner of the four attached pictures, and he has no information about ( Fire clay - Refractory clay - Heat resistant clay ) I don't expect he will know which of them has the least shrinkage.


Of the four above how do I know the least shrinkage?

Which of them do you recommend I try first?

Best Regards

[david s]

Dear David, Thank you for your response. I went to all the brick shops in my city and in two other cities, everyone says that they have no clay and that they have a problem in the supply chain like the rest of the world because of the disease.

The only source who has clay at this time is the owner of the four attached pictures, and he has no information about ( Fire clay - Refractory clay - Heat resistant clay ) I don't expect he will know which of them has the least shrinkage.


Of the four above how do I know the least shrinkage?

Which of them do you recommend I try first?

Best Regards

The cheapest. Fire clay for potters is a clay that can resist temperatures exceeding 1300C (2400F), so not required for us. Generally, the clay marked Ball Clay will be the cheapest.I'd suggest you get the one marked Clay which probably is Ball Clay and the cheapest. Some of the oxides listed in the contents can act as fluxes, but not at the temperatures we use so disregard that. Also the high alumina content is not relevant for us for the same reason.

Fire clay for a bricklayer is cheap clay to add to mortar to increase stickiness. Too much leads to shrinkage cracks on drying.

[ZIYAD]

My focus was 100% on alumina, iron and titanium oxide content I now understand that at the temperature used in pizza ovens the oxide content in the clay doesn't matter.

Thank you so much for sharing your time and knowledge with me and the readers.