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Homebrew set-up time?? - Forno Bravo Forum: The Wood-Fired Oven Community

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  • Homebrew set-up time??

    Hi everyone!
    I went out today to lay the second course of sailors, (I am stacking three sailors to gain some wall height before my dome starts. I surrounded my oven floor with the first course) as I buttered up my first brick with my Homebrew (3:1:1:1 mix) and put it down. I gave it a few taps with my rubber mallet I broke a few bonds on the course below. I lifted the first course off the insulation board. Some joints held and some joints broke off. The mortar would flake clean on one side of the brick and I could tap off the mortar on the other side of the brick. I cleaned off all the mortar with a hammer and chisel quite easily.

    My question is-
    How long does the mortar take to make a strong joint?

    I waited about 4 days before trying to set my next course. Everyday I noticed the mortar was getting harder but I could still scrap mortar off the sides of the bricks with my fingernail if I tried hard.

    Could it be my technique. I soaked the bricks for 30 seconds. Made a peanut butter mix. I also dipped the brick real quick before buttering , then I set the brick and tapped it with a rubber mallet into place.

    Some thoughts are-
    • Maybe I should not have dipped the brick then put mortar immediately on the brick.
    • Maybe I should not be tapping the bricks into place with mallet, this may break the bond
    • Maybe I should not use an old bag of Portland I had laying around


    I removed all the first course and since I had the mortar mixed (this time using new portland) and some more sailor bricks cut, I dipped the brick super quick, wiped it with a sponge, buttered just the brick in my hand and placed it. I did continue tapping the brick with a mallet, I like seeing the mortar ooze out the joint, maybe this is not making a strong bond.

    Is there a test I can do on my sailor course to tell if the joints have bonded before I start laying more bricks?

    •Do I need to butter both surfaces that go together or only on surface?

    Does everyone who use the Homebrew mortar mix feel like they could go out and give one of their bricks a slight yanks after a day or two and feel confident the the joint is strong OR does it take about a week before the mortar is strong and set-up?

    I have read every post that I could find about the Homebrew mortar but haven't found anything to cure my Mortar Anxiety.

    Thanks your patience!

  • #2
    I forgot to say I am using #30 silica sand in my Homebrew mix. Not sure that matters.

    Comment


    • #3
      You answered you own question, old portland will not set, the moisture in the air finds it way into the bags over time and makes it useless. FYI, three sailors would make the side walls quite high, see attached pic. and would require some type of buttressing to support the outward pressure from the dome.
      Russell
      Google Photo Album [https://photos.google.com/share/AF1Q...JneXVXc3hVNHd3/]

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      • #4
        Given that the base of a dome is the weakest part of the form, cracks nearly always start from the base, therefore long vertical joints are asking for problems in one course of sailors let alone three. Sailors are thinner than soldiers which further exacerbated the problem. Brick ovens are generally 4' thick. Laid on edge, only 3" thick is not considered strong enough because of the reduced thickness of the mortar joints. If you proceed with this design, please report back in a couple of years time as to its structural integrity.
        Last edited by david s; 09-09-2019, 01:21 PM.
        Kindled with zeal and fired with passion.

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        • #5
          Sorry Utah and Dave for the incorrect word use. I am stacking "stretchers" (flat half bricks stacked three high), Two of those courses are above the floor.

          Its been 24 hours since I laid my second attempt on my first course. I can use my finger and scrape scrape the excess mortar of the butt end of my half bricks fairly easy although the joints seem to be hard. Is this normal, do I need to be patient and let it dry more? I tried lifting straight up (minor force) on a second course start brick that I placed yesterday and it seemed solid. I didn't want to lift any more and break any joints. I just can't tell if I should continue upwards and onwards until I feel confident with my bricks bonding.

          I talked to a mason store manager. He said he never heard of such a home-brew mortar. He did say I should use mason sand for the sand mixture for strength. Maybe I will make up a couple batches, one for the tight joints on the face bricks and the mason sand to fill in the back gaps.

          The manager also suggested that when I dipped the brick right before I buttered it there was standing water on the bricks and that the bricks face could not have the hydraulic effect that it needs to bond. He also said that I could use a rubber mallet to lightly tap the bricks in place and I have more than a few seconds to mess with the bricks as long as I am not picking them up or sliding or moving them inches. So hitting them until the mortar squeezes out from the joints is ok.

          I want to tell myself that everything will be ok and I should continue but I would think the mortar would be hard and sticking to everything in a 24hr period.

          Comment


          • #6
            The bricks can be damp but not wet on the surface. Your cement, being old might not be working. Lime does have a retarding effect on setting time with Portland cement. Do you have the right lime? It should be builders lime (hydrated). What kind of powdered clay are you using? What is the ambient temperature range currently in your location?
            Kindled with zeal and fired with passion.

            Comment


            • #7
              After I removed my first course bricks because of a bond issue, I mixed up a new Homebrew with new Portland and re-layed the first course using new bricks as well. I quickly dipped each brick in a clean bucket of water and wiped off the bricks with a sponge.

              I am using a Hydrated lime type S. I am using Lincoln Fireclay. It is in the high 50's with lots of rain currently. The lows have been in the mid 40's. That is probably the perfect temp for mortar to take its time setting up. I just want to get the bricks laid before snow season (which will probably be here next week!)

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