36" Midwestern Pompeii

[RandyJ]

Make sure you have very small joints as there heat stop will crack if you are over 1\8". And yes it is pretty expensive stuff. Why did you decide to go that route and not with the home brew? You could have made all the mortar you need for the price of one bag of heat stop, and probably less. Just wondering.

Randy

[UtahBeehiver]

Heat Stop 50 is an expensive product but that is the builder's choice. However, 1/8" is only a recommended joint width. From the Heat Stop 50 spec sheet is the following:

• HEAT STOP-50 is provided in a 50 lb. bag only.
• For estimating purposes approximately 50 lbs. will lay up 100 firebricks (2 ^½ inch thick) if joint thickness is 1/16 to 1/8 inch as recommended.
• Joint thickness up to 1/2 inch is acceptable with this product and is quite common.

That said, you may need to taper your vent and front arch bricks to try and keep the outer edge of the joints within this tolerance.

[Larry P]

The joint size recommendations for heat stop 50 are intended for people building boxes (fireplaces) not domes. For that, you should be at 1/8" and would never exceed 1/2". There are plenty of builds here (including mine) using heat stop, and joint size has never been an issue.

Why did I chose heat stop? Because the calcium alumate cement will stand up better to heat than portland-based cements, and its expansion properties under heat are closer to that of firebrick. Does that matter? Based on experiences here, it's probably overkill, but on the other hand I would have saved about $100 by going with homebrew, on a project that will cost in the thousands. The cost is trivial enough to not question IMO.

[Saluki]

"Make sure you have very small joints as there heat stop will crack if you are over 1\8". And yes it is pretty expensive stuff. Why did you decide to go that route and not with the home brew? You could have made all the mortar you need for the price of one bag of heat stop, and probably less. Just wondering.

Randy"

I went with it simply because trying to source the contents of the homebrew looked to be a pain in the rear. The brickyard where I bought the firebricks from is about 2 miles from me and they gave me a great deal on buying everything from them. Will I have joints bigger than 1/8"? Sure I will, who doesn't?

I guess if its rated well past 2000 degrees at 1/2 joints, I should be good up till about a 3/4 joint

We'll see how it plays out once its fired but after reading builds on here for sometime I have yet to see an oven disintegrate regardless of joint thickness.

And when I need more, I can run to the yard and be back in less than 10 minutes.

[JRPizza]

Build is looking good. What kind of mortar are you using? The color is quite a bit different than the homebrew I used.

Hey, I wasn't trying to start a fight. I just saw the light grey color and was hoping you didn't use a predominately Portland mix

[UtahBeehiver]

I don't think there is any fight going on, different strokes for different folks. We just need to make sure that all the product parameters are presented, pros and cons. This is how we learn and pass good knowledge on the the next generation of builders.

[Saluki]

JRPIzza - I saw it nothing like that - Questions and answers stimulate discussion, which has helped me to jump into this project to begin with and can hopefully help others along in the journey.

[Saluki]

Got my IT together, had the innards from a half barrel I tore apart to hopefully start homebrewing and connected that between a bracket using all thread and the other end is welded to a magnetic door stop.

[RandyJ]

Sorry I must have been thinking of a different mortar. I was told by the guy I bought a lot of my bricks from that the mortar he had would crack if it had over a 1\8" joint, and I remember someone on the forum around that time having that happen to them. It must have been something else. I did not want to be mean just a warning. I guess I was misleading you. Also if you got a deal then that is good. It will be a little easier then too as you won't need to premix bigger batches and then portion it out.

Randy

[Saluki]

Well, I'm past the arch, which is a relief, although it gets a little tougher to reach in and clean the mortar from the inside.

[Saluki]

Its prob the same stuff Randy. I had actually planned to do the homebrew all along until it came time to gather supplies, then things change. I'm sure they'll change several time before I finish it.

[UtahBeehiver]

Saluki,

Looks like a little dreaded droop. Try and correct over a couple course rather than one course. Will need to get back on track (level) before you close the dome.

[Saluki]

It's not too bad, hardly noticeable really.

[Saluki]

I did learn something thou that may help others. I used the IT to determine the angle on the inside of the arch bricks. That angle works great for half bricks, but if you are making a custom cut, place a half brick in the bracket and trace the bottom of that onto the arch brick, it makes for a greater angle and the half bricks will fit better. I figured this out after cutting the last three unfortunately.

[UtahBeehiver]

I guess the picture skews things, looks like at least a couple inches lower in the front than the back from the pic.