36" Beginner WFO

[danjmath]

Thanks Gulf, I'll do that.
Did you use the reclaimed cuttings as thermal mass, or just in home-brew in place of fireclay?

I got a 10% box store coupon, so I am planning on ordering all the portland, lime, and possibly sand at once. Whats a rough estimate of how much I would need for 36" over(18" high)?

Also, I hear all sort of different home brew ratios.
Is the 3,1,1.,1, Sand, Fireclay, Portland, lime best, or has anyone come up with a better ratio?

Also, does the type of sand matter? Can I just go to my local quarry and load up a truck, or I am better buying the more expensive quikrete bagged sand(price may not matter to much depending on how much I need.)

*Edit-just saw quicrete playsand is on sale now as well, its a finer grained sand, would there be any problem in using that?

[david s]

IMO stick with the tried and tested 3:!:!:! recipe. Some folk would argue that it's too rich a mix for mortar, however if the portland fails then the only active ingredient is the lime. The clay at our WFO temperature range will not be rendered permanent (sintered), so it can also be considered as a fine aggregate only, leaving the resultant ratio at 5:1.
If you alter the recipe to 6:1:1:1, then when/if the portland fails you'd be left with an 8:1 mix, too weak IMO.

Regarding sand, any fine sand will suffice.

[Gulf]

Dan, David,

I'm all for the 3:1:1:1 recipe.

David,

I don't think that we can count the clay totaly out in the recipe when the portland fails (and, it will fail). I'll let the engineers do the pie-r-square, but a little lime added to a bunch of clay does wonders for the clay. I've seen muddy, undrivable roads, and construction locations turned into red concrete by just turning in some lime to the clay. There is a reaction beween the two that has nothing to do with heating it up to clay vitrifcation temps. It may not be rock hard but I believe that it will still hold the bricks apart.


Dan,

What ever sand you end up with, screen it before use in this application. I have bought truck loads of masonry sand, and bags of all purpose sand that had fairly large rocks in it. A small (less than pea gravel size) rock may not be a problem in normal use mortar. But, it may be in a refractory mortar that is subject to the temps that your oven will reach.

Edit:

Did you use the reclaimed cuttings as thermal mass, or just in home-brew in place of fireclay?

I could not access fireclay localy, so I reclaimed. I did not use any for thermal mass. But, I have seen folks go to extremes to crush firebrick chips up for grog when they probably threw enough away to do the job .

[danjmath]

Laid the structural hearth layer on Monday, and on Saturday I plan on putting down my 3" of p-crete.

I also went and bought my CaSi Board, ceramic blanket, and what was supposed to be fire-clay.......

I could only find one place around me that sold fire clay, and they only had 3 25 pound bags left in stock, $22 each. I left work a little early to pick them up, and got there just before they closed.

When I got home I looked at what I had picked up, and realized it was "FireRock Adhesive Mortar", and not just fireclay.
It kills me to, because I had planned on buying 1 bag and using reclaimed cutting for the rest, but since it so so far out of the way, I decided to just grab 2 just in case. I don't really feel like spending the hour and a half to go return them either.

I have heard some comments from people on the forum saying they would not recommend using it, but no comments on anyone that has actually used it.

So now for the questions
First, anyone have personal experience using firerock, or know if there are certain applications in the oven it would be good for, or if I could use it in a modified home brew?

Second, I am about to cut the bricks for the floor, and was wondering how people do rounded cuts on a tile saw? Are they just a series of strait cuts, or is there some trick to it.

Finally, also for the floor, I plan on doing the dome around, rather than on the cooking floor. Should I put a gap between the floor and first course, or just put them as close as possible.

Thanks for all the help. just updated my album as well.

[UtahBeehiver]

Is this what Interstate brick sold you as fire clay? It should be Muddox fire clay, abt $6 a 50lb bag. "Small" straight cuts and you can feather the points by using the side of the blade. Gulf did a diagram awhile back, do a search on his posts. Leave a gap, place a strip of cardboard between the floor edge the first course, it is about an 1/8" gap, leave in during build, keeps errant mortar out of expansion gap, it will burn out after a few firings. Also, run a duct or blue tape along where the expansion gap is to keep mortar out too. There has been some incidences of oven cracking due to the expansion gap being plugged up with mortar and the expansion has now where to go.

[danjmath]

Yea...thats what they sold me as fireclay, thought it was expensive, but couldn't find anyone else that carried it....

[UtahBeehiver]

Print off the pic I attached and take the fire mortar back and tell them this is what you want. HC Muddox mortar clay. It may be a little more than 6 bucks now but can't be that much more. It is a core material for bricklayers and masons. Who ever helped you must of miss understood what you needed. I assumed you went to the main plant on Old Bingham Highway in West Jordan?

[Gulf]

That's funny. A few weeks ago, I called the local Boral Brick and asked if they had fireclay. They said sure. So, I made the1 hour drive to their store. They were calling Heat Stop 50 "fireclay". There must be a conspiracy in the industry to steer folks away from affordable refractories .

There are several posts/threads about FireRock. Like you, I could not find processed clay locally. I started out with FireRock that I had bought from that same Boral Brick store. They had it on close out for half price. They were no longer selling RireRock fireplaces which the mortar went with. I think that FireRock is only rated for 1/8th inch joints. However, I did cheat on that up to about 3/8ths. I had some very wide outside joints that I later pointed with 50/50 FireRock and reclaimed fireclay homebrew mortar. I used all reclaimed homebrew on my entry and chimney. It is all still standing but, I am not advising that to anyone. If I had it to do all over again, it would be all homebrew. If I were you, I would not give up on trying to find the processed fireclay. I'm not sure about the chemistry. But,It might even react with the lime better than reclaimed fireclay. A mix of the two may be the way to go. That said, you would be surprised at how much material that you can get from the pan on your wet saw. If you will cut your floor brick and maybe the first row of dome brick, you will be well on your way to having enough clay to get started. Last week it took me 3 days to process my cuttings from the saw. I had 3 large baking pans that I set out in the sun. As the clay drys it becomes easier to break up. Each day I crumbled the chunks into smaller pieces. At the end of the 3rd day, I screened it and am now using that clay on my outdoor fireplace. Like, Russell, my advise is to take the Firerock back to the store.

[danjmath]

Finally ready to get back to work after a several weekends of "Vacation". I went back to Interstate and returned the Firerock then got the same fire mortar as Russel(I think its 6.99 now, not 6), they call it mortar clay, but its the same Muddox brand.
Been doing the math some more, and I for sure will not have enough brick. Close, but not quite. I guess that means some low-medium duty new stuff (rated to 1800, not sure what that makes it). Where would it be best to put this brick in the oven? I was thinking of using it for the cooking floor, but could also use it as the "soldier" row, or near the top if there is any reason to.

[danjmath]

How long should my Oven Landing be? It seems for ease of use you would want it to be as short as possible. Just planning on where to center my cooking floor before I get it in place.

[david s]

How long should my Oven Landing be? It seems for ease of use you would want it to be as short as possible. Just planning on where to center my cooking floor before I get it in place.

I agree,the first oven I built was a simple updraft design with a flue in the centre of the dome. The big advantages were no smoke at start up, it drew like a champ, and no entry to have to work past. I think the front flue design is better, giving superior circulation from the cross flow design and also more fuel efficient. If you are building the entry in brick it makes it difficult to build it shallow. I cast mine which enables a much shallower distance. Mine is only 5" deep with a decorative arch another 2.5" thick leaving a total of 7.5" allowing good access and the use of short handled tools.

[danjmath]

Got my CaSi down, and the floor all marked and ready to start cutting today.

I noticed that most entry arches usually go one of two ways, a full circular-ish arch, (Like the attached one I used from UtahBehivers), or one with strait sides then an arch on top (similar to the one in the Forno Bravo PDF).
Is there any advantage one over the other, or is it more of a aesthetic decision.
(Any tips or links to creating them wouldn't hurt either)

Also, how much of the home brew should I mix at once? Would it be a good idea to dry mix the ingredients together in large batches, then wet as needed, or would that not work.

[UtahBeehiver]

Builder's choice. However, depending on the type of chimney, ie brick vs SS pipe, the vertical walls of a straight wall will a partial arch "may" need some buttressing due to the inherent lateral forces of the arch on the vertical walls. On a hemisphere, this force is nominal. In either case, recommend a tapered inner arch to make the dome to arch transition smoother. Similar to what I told Mike.

I mixed 5 gallon homer buckets of dry home brew then mixed what I need. How much depends on how fast you can lay the bricks. Be sure to give bricks a quick dip in water before putting mortar on.

[david s]

Be careful about pre-mixing the mortar ingredients. Sand is usually quite moist when you buy it, I dry and seive my sand and then store it in sealed bins. If you add active ingredients like lime and cement to moist sand it will end up reacting with the water present and go hard and lumpy. Because of the hassle of drying the sand it is probably easier to make up small batches as you go.

[UtahBeehiver]

Good point, I used quartz sand that had been process dried.