Mark's 42" in MN

[AtTheLake]

Re: Mark's 42" in MN

I laid the floor on a 50/50 mix of fireclay and sand over the insulboard.
That mixture had water in it.
I think that is what the Pompeii instructions say to do.

[dmun]

Re: Mark's 42" in MN

I understood from the begining that keeping things dry was and is a big deal.

This is true whatever mortar you use. A wet oven is an unhappy oven.

[SCChris]

Re: Mark's 42" in MN

I too used Sairset and havn't had any problems. I understood from the begining that keeping things dry was and is a big deal. I wasn't going to be happy dealing with a wet oven and having to cure and recure whatever mortar I was going to use. I decided to build an oven enclosure and with the enclosure decision I gained insulating space. I'm delighted with the oven's performance, the ability to hold heat is amazing in my opinion. Sairset or whatever is fine as long as the environment and the mortar are matched..

Chris

[Tman1]

Re: Mark's 42" in MN

Wait a minute! Your insulation board is soaking up moisture? Is it wicking from the course bricks so its mostly on the outside? You need to make sure that gets dried out.

[AtTheLake]

Re: Mark's 42" in MN

Where's my Advil?
Aside from a major backache the first day went pretty well (I think).
Laid the floor and 2 courses of brick.
Worst part was dealing with the insulboard sucking the moisture out of the fireclay mix under the floor. It wouldn't have been so bad, but I had a brain fart starting my herring bone pattern and had to lift and reset about 10 bricks. Must of got too excited to finally be setting bricks.

Can't seem to be able to post pictures from my phone.
All I get is a grayed out Choose File button on the attachment page.

Mark

[AtTheLake]

Re: Mark's 42" in MN

Thanks Dmun and Splatgirl
I had already decided to not use the wet premixed.
My only indecision is about buying Forno Bravos mix. (shipping costs)

Mark

Ps please pardon my spelling and punctuation errors
I am At The Lake now so everything is via my phone
But don't worry I am not into the OMGs, LOLs, IMHOs, and all the other texting slang.

[dmun]

Re: Mark's 42" in MN

Splatgirl used sairset, and therefore is qualified to speak on the subject in a way that I'm not.

That said, the history of wet premix mortars goes back a long way on the board. I read every post for a year before I put shovel to dirt, and learned a lot from multiple builders before I begin. The original ovens were very simple affairs, with brickset halved bricks, and angle iron over the doors. An early and influential builder was Paulages. This was in the summer of 2005. He was an early brick arch adapter. His was the first corner-entry build. He was one of the first to scope out Harbison-Walker, and all they have to offer. He was the first to use tapered firebricks, medium duty firebricks, refractory tiles, castable refractory for the vent. He was the last to use the vermiculite layer under the support slab, and his build was one of the main reasons we don't do that anymore. One of the things he got from H-W was wet, premix mortar. He found it so unworkable that he re-did the courses he built with the stuff.

It's really interesting to go back and read Paulages' build, as i just did. He was in a real sense my teacher here, and you tend to stick to the things you learn early, unless there is a real reason to jettison them.

We've had lots of subsequent problems with the "wet stuff". This isn't exactly an irrational prejudice. What I would say to those contemplating using wet premix mortar is that they should plan on keeping their oven as dry as a cobb oven.

[splatgirl]

Re: Mark's 42" in MN

With all due respect to the dmun, every example here where wet premix mortar "has proven problematic again and again" is when people have allowed their ovens in progress to get wet or rained on. As far as I know, beyond that one known issue, we have no other long or short term info to judge it on.

I used Sairset, kept my oven dry during my build, and it was and continues to be perfectly fine. I found not needing to worry about the timing of cement based mortars a HUGE advantage as it allowed me to work in dribs and drabs without having to mix/slake/waste mortar just to get in a half hours' worth of work. It's a decision I would be fine with making the same way again.
Of course I have no idea how my oven will fare in the next 20 or 30 years vs. ovens mortared with homebrew or Heatstop, but I don't know how my person or anything else about my life will fare in that time period, either. I guess I have better things to worry about.

[dmun]

Re: Mark's 42" in MN

Wet premix mortar has proved problematic again and again. You won't regret the decision to use the homebrew.

[stoveup]

Re: Mark's 42" in MN

If the nations of the world would put aside their differences, build a bunch of Pompeii ovens and bake some warm bread to share, we would all be better for it.

Well said, Tapir Force. Let's argue about recipes, not religion and politics.

[AtTheLake]

Re: Mark's 42" in MN

I decided to forgo the Grog for now. Like Splatgirl said I can always use scraps to fill in the voids.
My greatest concern/anxiety is the decision to use Homebrew mortar. I know there are many builders on this forum that use it. That is why I went away from the Sairset. But when I consider the total investment in this project, time/money I would hate to have something go wrong trying to save a few dollars.
So I am thinking about calling FB and ordering 4 bags of their mix. Call it a Piece of Mind thing. Besides I feel like I owe them something. I could call it my donation to a good cause.

Mark

Also, Splatgirl
1 layer 2" thick
I bought enough insulboard for 6x4.
I will be cutting a little of the length and adding it to the side to get to the 51" required width.

[dmun]

Re: Mark's 42" in MN

In my misspent youth as a potter, grog was crushed fired pottery, added to clay to reduce shrinkage for thick wall hand built (as opposed to wheel thrown) pottery. This said, we got it out of bags labeled "grog", not from smashing failed pots, so I don't really know what it was.

Wikipedia seems to think it's a refractory material.

[Tman1]

Re: Mark's 42" in MN

Italian Master builder Stefano Ferrara builds his ovens by filling in the cracks with some 'grog'. If you look into stuff on the web long enough you can find a bunch of info about it. I wouldn't think FB has a problem with me posting stuff about him, but just in case I'll let your fingers do the walking.

[splatgirl]

Re: Mark's 42" in MN

p.s. that is a lot of insulation board...are you putting two or three layers under the hearth, or what? If that's the case, consider adjusting the height of your block stand or your opening will end up pretty high.

[splatgirl]

Re: Mark's 42" in MN

I haven't heard it referred to as grog, but the suggestion of using scrap wedges of brick in the bigger joints is out there. I did it--more as a means of propping up and maintaining the angle on the steeper courses while my mortar set--but either way, it is a valid method for reducing the amount of mortar/joint size.