36" build in Tallahassee - AKA Bruce's Folly

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I read on the Internet (so it must be true) that the hw 413 was could be used in place of the fb mortar.

Reviving an old thread.
I was trying to find a local San Diego source for refractory Mortar, blanket and Insullation Boards. Found a local distributor (squiresbelt.com) for equivalents to all three, though only the mortar is going to save me any money.

Sent the FB spec sheets to HW and got the following response (my price comparison in parens):

"The Harbison-Walker Refractory equivalent to the RefMix mortar is MORTAR MIX 413 (50lbs = $35; vs. FB 22lbs = $35). As you continue to search for alternate refractory sources for this material, keep in mind that it is important that a high temperature mortar used for outdoor ovens exposed to weather must be hydraulically bonded. MORTAR MIX 413 was developed for this application. Most refractory mortars are alkali silicate-bonded and have binder systems that are somewhat water soluble. This causes them to degrade with extended service in outdoor ovens.

Hopefully this is the case and just my needing to move up the learning curve in terms of the consistency of the mix and it applying to the bricks. I have been watching you tube videos of brick being laid. Depending on weather, I will mix some up and try again tomorrow. I probably needed a reality check about now, the build had been going so smoothly. Bruce

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Gudday Bruce
I have not used hi temp mortar so I hope someone chips in with some better detail.From what I have read. Hi temp mortar doesn't "cure" as such at first only drys off its water content it cures only after it heated during your ovens curing fires. So it appears the bond between the brick will be delicate? ( I hope that's the right word) till fired I suspect.
Regards dave

I'm hoping I have the correct mortar (see the previous post). If not, I'll have to try harder to find a source for the lime. Bruce

[brickie in oz]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Has any of it actually set?
How long have the bricks been laid?

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Has any of it actually set?
How long have the bricks been laid?

It has been about 20 hours now. The mortar seems to have set though none of the bricks stuck together. This is shown in the first two images.

The remaining images are from this a.m. After looking at the videos, it appeared I made a number of mistakes in my first attempt in addition to adding too much water to the mix. I was only buttering one side of the bricks and not using enough mortar. I mixed up a small amount of mortar and tried to get to the consistency of "peanut butter." I hand mixed with the trowel but the mix acted like natural peanut butter with oil (in this case water) coming to the top. The mix would seem thick enough but as the water came out, when mixed back up it would be too thin. When I thought I had the correct consistency, I tried mortaring some of the brick cuttings. I buttered both sides and gently pressed together, using the trowel to remove some of the excess. After the mortar seemed to be setting, I used a wet rag to clean the surface of the first three joints but left the last with extra mortar on top. Looks like these have a pretty good chance of working.

If you look carefully at the last image, water can be seen pooling on top of the mortar. This was also occurring with the first three joints, with very thin watery mortar oozing out the edges of the joints. If the mortar was allowed to rest a minute of so, this would also occur to the mortar in the tray. Does this mean the mortar was still too wet or not mechanically mix enough? Or for that matter, is it normal.

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Reread the High Heat Mortar Primer sticky. Looks like I could have used home brew from the beginning.

Not really sure how I missed this posting and apologize for it...type N masonry cement is mixed at 50/50 portland to lime as is portland lime mix...in this instance it should be 2 parts cement 1 fireclay and 3 sand...that is exactly what I used for our oven build and it dried nice and hard quite quickly...although we haven't fired it yet I am confident in it as a mix...that will also work well for rendering the dome if that is how you plan to finish it as the type N is a bit stickier than other types of mortar...for the render you can add more sand...typically type N gets anywhere from 6 to 9 parts sand when being used to lay brick
Best
Dutch

The type N masonry cement appears locally available.

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I googled for instructions and found this:

Pre-mixed Mortar

This is the easiest mortar of all to make. Pre-mixed mortar is a combination of Portland Cement, Hydrated Lime, and Masonry Sand already blended together in the proper proportions to make a Type S mortar. All that is needed is to add sufficient water to achieve the desired consistency, usually about 5 to 6 quarts for an 80# bag. Pre-mixed mortars are a little unique in that they require a slightly modified mixing procedure.

Mixing Procedure

Put 2/3 to 3/4 of the water into the mixer
Add the Pre-mixed mortar into the mixer, adding water as necessary to achieve the desired consistency
Mix for 3 to5 minutes, turn off the mixer and allow mortar to ?slake? for 2 to 3 minutes, re-start the mixer and mix for an additional 2 to 3 minutes adding water as necessary to achieve desired consistency.
Pre-mixed mortars use a kiln dried sand that has a higher water demand. It takes a few minutes for all of the water to be absorbed into the dry sand, hence the need for a prolonged mixing time. If you do not allow the mortar to set and ?slake?, it will feel gritty on the trowel and will be difficult to work with.

Do these instructions sound right, if so, I have not been mixing nearly enough. Bruce

[cobblerdave]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Gudday Bruce
Mixing small batches .....get one of those cheap paint mixers the one designed to mix 20 lt cans. Just put it on your electric drill . Full a bucket of water and use a dipper so you have better control over how much water goes in, never be tempted to use the hose!

The trowel pictured is easy to use due to the round end( brickie by this stage is not impressed as its use is for plastering )
The vinegar is to take the sting out of your hands after you can't help yourself and play with the mortar. No it will not heal them the damage is done
Regards Dave

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Gudday Bruce
[ATTACH]35324[/ATTACH]
The trowel pictured is easy to use due to the round end( brickie by this stage is not impressed as its use is for plastering )

Look what I have:

[brickie in oz]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Gudday ( brickie by this stage is not impressed as its use is for plastering )

I think youll find it was Rockcutter who said that......

That style of trowel is used mainly by roof tilers here in Oz, not plasterers.

[brickie in oz]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I was only buttering one side of the bricks and not using enough mortar.

You should only have to butter one side.

I mixed up a small amount of mortar and tried to get to the consistency of "peanut butter." I hand mixed with the trowel but the mix acted like natural peanut butter with oil (in this case water) coming to the top.

I always advocate a small dash of dish washing detergent, it will coat all the particles in the mix and stop them repelling the water.

I worked with so many other bricklayers over the years who absolutely struggled with their mortar and the water bleed off, they would spend all day knocking up the mortar, (remixing) it gets even worse in hot weather.
They can not believe the difference in the mortar when I tell them about using a surfactant in the mix.

The mix would seem thick enough but as the water came out, when mixed back up it would be too thin.

See above.

with very thin watery mortar oozing out the edges of the joints. If the mortar was allowed to rest a minute of so, this would also occur to the mortar in the tray.

This again is water bleed, your bricks are obviously wet, in the trade Ive had to lay wet bricks due to the weather catching us out, it happens mainly with solids but they actually float on the thin film of water, and you can see it oozing out from between the brick and the mortar.
Its not desirable because the bond from brick to mortar is lost.
It wont happen to wire cuts, the ones with the holes, as the water fills the holes.

Does this mean the mortar was still too wet or not mechanically mix enough? Or for that matter, is it normal.

5 minutes is plenty of time to mix mortar.

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Brickie (Al), thanks for your help.

You should only have to butter one side.


I always advocate a small dash of dish washing detergent, it will coat all the particles in the mix and stop them repelling the water.

I worked with so many other bricklayers over the years who absolutely struggled with their mortar and the water bleed off, they would spend all day knocking up the mortar, (remixing) it gets even worse in hot weather.
They can not believe the difference in the mortar when I tell them about using a surfactant in the mix.

5 minutes is plenty of time to mix mortar.

I think the main problem was not using enough motar the first time (when none of the bricks held together), along with too thin and poorly mixed mortar. My second attempt, even with the bleed off appear to have set and look good. So I am at least crawling up the learning curve.

I will try the dish washing detergent and mixing for about 5 minutes with the drill and paddle. Looks like the rain is holding off this a.m. and I should get a chance to give it a try. Bruce

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Was able to mortar most of the way around the perimeter doing some in the am and some this evening. Seems to be going better and mixed the mortar with a little detergent per brickie and used the drill attachment per cobblerdave. I would guess about 3/4 of joints will hold, most of the rest broke when I moved the adjacent bricks and separated the joint. Still, think I am done crawling and now taking baby steps on the learning curve.

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

I would guess about 3/4 of joints will hold, most of the rest broke when I moved the adjacent bricks and separated the joint. Still, think I am done crawling and now taking baby steps on the learning curve.

Rain again today. I pulled up the edges of the tarp and checked the joints. Turns out almost all the joints held together except for two bricks that caught up on the edge of the plywood when I pushed it too far back after the mortar had set. Looking forward to getting to work on the dome.

[cobblerdave]

Re: 36" build in Tallahassee - AKA Bruce's Folly

Gudday Bruce
Good to find out that the brick works holding and now and it just down to bond time.
I laughed when you said you were taking baby steps . My wife recons I am going back to childhood.....playing with mud ....fascination with fire!!!!
Regards dave
Sunny day in my part of the planet so back to playing with my brick veneer

[Bec1208]

Re: 36" build in Tallahassee - AKA Bruce's Folly

The rain stopped for awhile so I was able to cut and layout the next course. Can I use the vertical bricks on each side of the entry?