Refractory Mortar Poll Tools, Tips and Techniques Discuss Refractory Mortar Poll in the Pizza Oven Design and Installation forums; Thanks a lot. Maybe I'll use homebrew for most of it and buy one bag of HeatStop for the arch, ...

[kebwi]

Thanks a lot. Maybe I'll use homebrew for most of it and buy one bag of HeatStop for the arch, or something to that effect. I don't really know.

I need to get the "right" homebrew ingredients I suppose. Is there variation in fireclay or lime? I honestly don't know. As to sand, my understanding is really fine white sand is my goal, finer than normal playground sand.

Is that right? What about lime or fireclay? Is there variation in those?

[Lars]

I am sure in the Seattle area you have many clay artists and fireclay suppliers. The sand is often called silica sand, ( about 4-5$ at Lowes or Home Depot)

Lime is lime... Portland come is 90lb bags for about $12
So, to get started, you will only spend about 12+20+12+12.~ $56 for 150lbs of sand, 80lbs of fireclay, 90 lbs of Portland, and 90 lbs of lime... enough to do most of the oven, if not the entire thing.

[DimTex]

I used the home made formula from the plans. For me it worked out well and I felt I had a little more control in how it worked (sand particle size, amount of fireclay). Building this oven in Texas during the hottest summer I can recall made this control all the more important. Besides the cost of buying sand, fireclay, lime and Portland cement locally was so much cheaper I would probably do it again.

[cynon767]

I am only on the third chain up, but have been using a homebrew mix slightly higher in sand and clay than the one in the plans, of 4:2:1:1. So far, anyway, it is going well.

[kebwi]

@cynon767: May I ask your reasoning for altering the ratios? I'm unclear on the motivation for the original ratios.

[cynon767]

kebwi- Initially, it was an accident. I had extra clay/sand left over from leveling the floor, and mixed it into the rest of the ingredients at the incorrect proportion. After reading up on the forum out of fear that I had done something terribly wrong, I came to the conclusion that it was probably fine. The word around the forum is that portland burns out at higher temps, so it's basically just there to harden up and hold things together until the clay/lime/sand can fire into dozens of little keystones. With extra fireclay, the mix was very creamy, spreadable, and sticky. The extra sand seems to balance out the clay and I haven't had any real cracking from shrinkage. I did end up with a few cracks in the soldier course while setting the second in place, but I'm pretty sure that was from a combination of having set the soldiers too dry and too-vigorously tapping the bricks in the second course to fit into place.

Upon reflection, the mix was more like 3.5:2:1:1 (3 1/2 sand, not 4 as previously stated.) Very similar to both Lars and Berryst.

If I remember correctly, the original mix was based on a low-portland mortar with fireclay added for thermal stability.

[papavino]

Heatstop 50. It was readily available, albeit about $76 a bag. Used about 3 1/3 bags for my 36" pompeii.

[philiph4@ameritech.net]

I used Plibrico Super Demon pre-mixed mortar. Has anyone else used this stuff?

[dmun]

I used Plibrico Super Demon pre-mixed mortar.

Is this the wet stuff in tubs? This has a bad reputation around here (won't dry, isn't waterproof etc) but let us know about the brand you're using.

[ThisOldGarageNJ]

is it refractory ?