Mortar Choices

[tdibratt]

Hi I have a question for the community. The last oven I built I used a combination of pre-mixed refractory mortar for the inside joints and then filled the outer larger joints of the bricks with a mix of sand, clay and portland cement as described in Allan Scott's Bread Builders book. The reason for this is because the pre-mixed stuff did not reccomend large joints and it was more expensive than the home made brew. So far 2+ years later no visible issues or damage has occurred to it. But as usual I always try to improve on things and after all it is a big exepense to build one and last thing I would want to see is it fail and crumble before my eyes.

Are some of you just using Heastop 50 dry mix and filling the entire gap? As you roll the top of the dome those outer edges are pretty big gaps.

Thx.

[e15757]

Re: Mortar Choices

I just completed my dome last weekend. Used Heatstop for the whole thing. The best thing I liked about it was the tacky quick-set properties. I didn't use any forms to build my dome. Once two bricks were set in a course they would support themselves in place...vertically. The downside is that I used 2.5 40lb bags at $60 a bag.

The rest of the story is that I started with one of the premix refractory cements, forget the name at the moment. Was to thin for my liking and I found it difficult to work with...have nearly a full bucket sitting in the garage and not sure what to do with it.

The other panic attack I had was that my local distributer only had two bags of Heatstop and I polished that off just as I was at the final 3 courses....yeah the toughest ones. So I bought the fireclay, mortar, and sand and tried that approach. I'm sure it works great but after building with no forms up until that point I didn't want to stop what I was doing and start working on forms, and my fireclay mixture was not going to support those last few courses without a form. So I called my distributer and he luckily had found another bag...so the day was saved.
Summary: of the three I tried; Heatstop, Pre-Mix, and homemade the Heatstop was by far the easiest to work with.

[e15757]

Re: Mortar Choices

I should also mention that I did use the "Homebrew" to do the cladding coat once the brick work was complete.

[tdibratt]

Re: Mortar Choices

When I did the last one I could not find fireclay specifically. I ended up buying Gold Art Clay which is used for making clay products and is fired in kilns to get it's strength. Got it from a local art supply store. When folks refer to fireclay is this the same thing or actually another product that is best suited for the home brew?

Thx

[RCLake]

Re: Mortar Choices

I used 4-50 lb bags of Heat Stop 50 to do my 42" dome. I needed to fix a crack from the arch area to the top (also redid my vent) and felt I should send some business to James so I bought a bag of refmix from him.

The refmix was by far much stronger but a bit harder to work with (keep the bricks wet!). It's to bad the shipping cost is so high or I would recommend everyone going that way. Getting a bag to do the tie in of the dome to the front opening is something I would suggest strongly.

[RTflorida]

Re: Mortar Choices

I used the Heatstop 50, good stuff. No issues with the wide joints - then again, my largest joints were only 1/4" between courses (on the outer face of the bricks), minimal to no mortar on the inside or on the sides (cut to fit with only enough side to side gap for a thin "glue coat" or mortar). Really would have like to try the refmix....I was even willing to eat the high shipping, but FB was out of stock and it was backordered.....I had no patience and couldn't wait. RC is one of a few that have used both and all seem to agree it sets stronger and harder than Heatstop. I would say if you can afford it, go with the best (and don't worry about the gaps, unless you are really deviating from the basic plans and creating some huge gaps - which case I would rethink the project).

RT

[tdibratt]

Re: Mortar Choices

Seems I am having trouble getting HeatStop 50. A local masonary supply store carries Alsey Flue Set Mortar which he says is essentially the same thing. Comes in dry form 50 LB bag and costs $90.00.

Alsey Refractories Co.: Firebrick, Mortar, Castables, Stain and Private Brand Products

Does anyone have any experience with this?

Thx

[RTflorida]

Re: Mortar Choices

OUCH! They think highly of their refractory mortar in Toronto......I only paid $55 for HeatStop 50. You should send a message to CJ (CanuckJim), I'm sure he can help you in sourcing affordable materials in your area. He is one of the most knowledgeable and helpful forum members.

RT

[sarah h]

Re: Mortar Choices

Tdibratt,

I'm in Ottawa and ran into the same problem last year - $90, almost double the U.S. prices everyone else is paying, and especially irritating when the two currencies are pretty much on par (give or take a few cents)!

I tried haggling with no success so I drove to Watertown. You might want to consider taking a drive to Buffalo.

Where the flue set mortar, I don't feel qualified to comment on its suitability but I wouldn't just take the saleman's word for it as many people on this forum have been wrongfully assured that lots of other products are a good substitute - most are not. RTflorida's right - ask Canuck Jim (send a private message to ensure he sees it).

Good luck!

[tdibratt]

Re: Mortar Choices

I actually sent Superior Clay an email on this and here is what I got back. Seems i may be able to get it special order and I am sure it will be pricey. Most other places just carry CPD premixed. Alphatherm sells Superwet 3000 but they tell me they do not think it is non-water soluable.

Tony,

I looked around at the history of our dealers in the Toronto area and I didn't see anyone who was likely to stock the Heat Stop 50. There were several folks who had the Heat Stop Wet Mix. Any of those dealers would be able to order it for you. Your best bet would probably be Mason's Masonry. They have yards in Mississauga and Richmond Hill. I would contact them (I'm sure you already have once) and see if they'll order it for you. It shouldn't be a problem. There aren't as many people who currently inventory the dry mix Heat Stop. That trend is changing and I think within the next several years it will be more commonplace.

Thank You,

Dave Kopp
Superior Clay Corp.

[SpringJim]

Re: Mortar Choices

The rest of the story is that I started with one of the premix refractory cements, forget the name at the moment. Was to thin for my liking and I found it difficult to work with...have nearly a full bucket sitting in the garage and not sure what to do with it.

Has anybody added some sand to the thinner premix to fatten it up?

(I think it's best use is for flat firebrick mortar and brick dipping)

Jim

[mannextdoor]

Re: Mortar Choices

I just completed my dome last weekend. Used Heatstop for the whole thing. The best thing I liked about it was the tacky quick-set properties. I didn't use any forms to build my dome. Once two bricks were set in a course they would support themselves in place...vertically. The downside is that I used 2.5 40lb bags at $60 a bag.

The rest of the story is that I started with one of the premix refractory cements, forget the name at the moment. Was to thin for my liking and I found it difficult to work with...have nearly a full bucket sitting in the garage and not sure what to do with it.

The other panic attack I had was that my local distributer only had two bags of Heatstop and I polished that off just as I was at the final 3 courses....yeah the toughest ones. So I bought the fireclay, mortar, and sand and tried that approach. I'm sure it works great but after building with no forms up until that point I didn't want to stop what I was doing and start working on forms, and my fireclay mixture was not going to support those last few courses without a form. So I called my distributer and he luckily had found another bag...so the day was saved.
Summary: of the three I tried; Heatstop, Pre-Mix, and homemade the Heatstop was by far the easiest to work with.

Just getting started on my oven. I would like to know if you cut every brick on a tapper and how thick you joints were?

[e15757]

Re: Mortar Choices

Hi yes I did cut every brick on taper.. Not sure I'd do that again. I also oriented the bricks vertically in the long direction rather than horizontally. I started by creating an arch on a flat surface to get my measurements. What I totally forgot to account for is the three dimensional aspect of a dome and the fact that a double angle cut is needed on each brick...actually three cuts on most bricks (angle on vertical top and vertical bottom to form the dome and a taper on horizontal either left or right side to account for curvature going around the dome. Most of the inward facing joints have small joint, only where I squeezed the mortar through. Back side still has the gaps most in the 1/2" to 3/4" range. Hope that helps, if you have more questions let me know.

[mannextdoor]

Re: Mortar Choices

Thanks. That is a big help. Did you use the heat stop 50 to cover the dome as well when finished? Some ovens have 2" or more of a cap put over it. Did you do this and how thick of a cap did you use? I am trying to find out what kind of coverage you were able to get out of you 2.5 bags of heat stop, and where it went.

[e15757]

Re: Mortar Choices

For refernece purposes the dome I created is 39". Two bags of Heat Stop got me up to about the final 15-20 bricks, including a very light skim coat of mortar on the outside of the dome I probably only used 1/4 or less of the third bag. I prob actually have close to 3/4 or more of the final bag remaining. As it stands now I have 1/2-3/4" of cladding on the outside that was made with the fireclay-mortar homebrew. I guess that's my question to the board as well. Am I good with this cladding or should I put something thicker?