Oven Dome Mortar Mix?

[EricU]

I will be starting my 42" diameter WFO dome (I have a lot of pics posted in the thread My Build ) and I need some clarification on the mortar mix to use for the fire bricks that make up the dome.

Is the following mix the one to use?

1 part portland
3 parts sand
1 part lime
1 part fire clay

And for the sand, can I use the standard plaster sand that I normally use for masonary work?



Thank you, Eric.

[EricU]

Re: Oven Dome Mortar Mix?

Or should I use "Heat Stop"?

I could not find the link to the FB product? and wouldnt the shipping on a 50# bag kill?

Thanks again, Eric.

[nissanneill]

Re: Oven Dome Mortar Mix?

Hi Eric,
I would use (as I did on my 40" Pompeii build) brickie sand rather than plastering/rendering sand. I believe this is a little more 'fatty' than plaster and.
I personally would not use the refractory cement as I have not been impressed by the many postings in this forum reporting considerable cracking when using it when (please correct me if I'm mistaken folks), but I haven't seen one report of cracks when using the 'poor man's mortar mix.

Cheers.

Neill

[dmun]

Re: Oven Dome Mortar Mix?

As to the question of sand, it's reported that really fine sand makes a difference when mortaring our narrow joints.

[EricU]

Re: Oven Dome Mortar Mix?

So where does one get the finer sand? When I do masonary work, I just go to the yard and ask for "plaster sand"?

Thanks for the help, I really dont think I would have done this project without this forum and your guys help.

Eric.

[dmun]

Re: Oven Dome Mortar Mix?

It's sometimes called "silica sand" and it's sold in various meshes for abrasive finishing, or sandblasting.

[EricU]

Re: Oven Dome Mortar Mix?

It's sometimes called "silica sand" and it's sold in various meshes for abrasive finishing, or sandblasting.

But Where do I get this finer sand?

Thanks, Eric.

[fxpose]

Re: Oven Dome Mortar Mix?

But Where do I get this finer sand?

I picked up a 100lb bag of silica sand at Home Depot.

George

[Tscarborough]

Re: Oven Dome Mortar Mix?

Plaster sand, AKA Torpedo sand, AKA concrete sand, AKA setting sand has too big of aggregate allowed (up to 1/4"). Since the goal is 1/16th joints (but the reality is <3/8"), any fine sand will work. Masonry sand, play sand, sugar sand, finer grade blasting sands, but NOT All Purpose sand.

[EricU]

Re: Oven Dome Mortar Mix?

I picked up a 100lb bag of silica sand at Home Depot.

George

Home Depot I have heard of! As a matter of fact I have my own parking spot and they all yell "ERIC" when I walk in!


Thanks for the lead, Eric.

[dmun]

Re: Oven Dome Mortar Mix?

The term "silica sand" is misleading because that's what sand is: silica, or quartz busted up into little pieces.

[stormy]

Re: Oven Dome Mortar Mix?

Sand can have a lot of different minerals in it and still be called sand but silica sand is considered more pure and is not as likely to explode under high heat. Little pieces of sandstone can still hold water and when heated can expand and blow apart. Silica sand is from quartz rock and is very stable under high heat, very pure silica sand is used in making glass.

[C5dad]

Re: Oven Dome Mortar Mix?

Eric,

Get the 30 Grit silica sand. Sometimes, my local HD/Lowes will have it in super sacks of about 500 lb for the price of 2.5 sacs of regular! It has been great mixing my own mud with the stuff for the last few days!

[azpizzanut]

Re: Oven Dome Mortar Mix?

Hi EricU,

Did anyone answer your specific question about the correct mortar mix? There are several variations and ratios mentioned on the forum when I searched. I recently used 1: 1: 1: 9, fire clay, Portland, hydrated lime, 60 mesh sand, for a small job. I thought the mix was a little heavy on the sand but it handled well and hardened up just fine. Other mixes use more Portland, fire clay and lime. Here is a mix recommended by a popular oven builder who has his own site. 10 sand: 6 clay: 2 Portland: 3 lime.

As to the sand issue, I found silica sand easily at HD, builders supply and brick yards. It is often used for sand blasting and it comes in various mesh sizes (as previously mentioned). I've used both 60 and 120 mesh without any noticeable difference. Fire clay is easy to find at the builders supply stores. My local HD stores didn't carry it.

I used HeatStop 50 for the joints in my precast oven panels and some chimney joints. It is rock solid when the joints are thin. There is shrinkage cracking on joints over 1/4", but that is to be expected since joints of that size and larger are not recommended. The "cracks" appear between the bricks and not along an edge. I just smeared in a bit of fresh mix with my finger the next day and there was no more apparent "cracking". I like HS 50 since a little goes a long way if you use thin joints. You can fill the larger gaps with home made refractory mortar. See "Combine Mortars" in the Newbie Forum.

Cheers,

[wemme]

Re: Oven Dome Mortar Mix?

Hello I'm about to start laying bricks. couple of questions?
1/ Is there a recommend method to mixing?
2/ I hear lime can burn as its costic is this true?
3/ Any other last minute advice?

Regards
Bart

http://www.fornobravo.com/forum/f2/o...-nz-14012.html