opinions on uni-bond 33 mortar?

[semlin]

is anyone familiar with uni-bond 33 mortar from united refractories? i searched and it is described as "alumina-silica, super duty, air setting, mortar that is used for laying, surfacing, and bonding firebrick"and the chemical analysis is "AI₂O₃ 48.5% SiO₂ 44.5% Other 7.0%" which seems like high alumina firebrick.

the refractory place i used said it would be fine for this application and they have supplied it for pizza ovens before, but i have seen the warnings here about using pre-mixed mortar here so i wanted sto check. i can't find an application guide for it. here is the information i can see.


https://www.soundingstone.com/produc...ant=9850962372

http://urc4u.com/urc-products

[UtahBeehiver]

I see the links on the manufacturer site has a Request for Information, have you asked for installation specs from them?

[semlin]

i have emailed the manufacturer, but i am not 100% sure what to ask. i asked if it was suitable for wide mortar joints.

[UtahBeehiver]

Installation Specs, that said, most of the refractory mortars I have seen, IE HeatStop 50, etc recommend small mortar joint 1/16" to 1/8" with a max of 3/8". You will see mortar joints larger than this on the back side of the dome. There have been some builders on the forum who have used HeatStop 50 on the larger than 3/8" joints. Have you consider homebrew?

[shanxk8]

My memory (albeit foggy) is that the premixed heat stop was water soluble, while the dry version was not water soluble.

[shanxk8]

I am using heat stop 50 ( dry) currently, and it seems to be working well with back (outside of dome) joints large than 3/8"

[semlin]

i did ask for an application guide. i will see what they say. do you think i can blend this stuff with sand or firebrick if need be?

long story short, i received three buckets of this stuff shipped on a pallet with my bricks and blankets from a refractory supplier. i did talk to the refractory place about wide mortar joints and they were reassuring this was suitable and was basic firebrick mortar. i misunderstood and thought i was getting three bags of dry mortar so i was not too worried, but now am worried due to other threads where buckets of refractory mortar do not seem to work..

[UtahBeehiver]

Can't comment on mixing in sand or firebrick with a commercial product, never have done it. I will defer comment to those who have used commercial refractory mortar on large mortar joints.

[Toomulla]

I believe the caution expressed on this site relates to using the product in joints wider then the size recommended by the manufacturer. I used tapered bricks and cut the size bevels to maintain a 1.5 mm joint and used a similar product very successfully. If you intend to install the bricks without cutting the tapers and bevels necessary to maintain the recommended joint width I would not use this product

[shanxk8]

Would commercial refractory mortars be different than what FB sells dry (bagged) in the Pompeii kits?

[SAG]

How did you get on with the unibond?