Thursday, August 27, 2009

Devil in the Details

What they don't mention is that bricks, Super, High, Medium and Insulated Fire Brick (IFB) are not the exact same size. I am using the 3" x 4 1/2 x9 inch series of brick and have mixed the various grades of bricks in the kiln. I used Super duty around the firebox, High duty for the inner shell and medium duty for the door and upper chimney. The outer shell is made from IFB. As you can see from the photos below, these bricks differ just a bit in height. If you are using a mortar, then the difference is taken care of. I am doing a bit of mortar in critical areas, but for the most part I am dry stacking the bricks with just a skim coat of fire clay and sand to seal and level a bit.

So at the header course, I have to deal with cutting the IFB back level to the hard brick. A pain, but not too bad as the IFB easily cuts with a hand saw. Unfortunately, my brick saw will not handle the brick on edge without making a double cut. The 4 1/2" is just too tall to make the cut in a single pass. Only two more header layers to go, layers 14 and 18. Layer 18 is the base for the arch.


  1. Making them all uniform would be just a tad too easy. And besides, this way you get to use your engineering skills.

  2. That looks familiar. Ours were just a tad closer and we made up the difference with some extra mortar. Hope that wasn't a mistake!

    We are utilizing used hard bricks of different brands and types, so there's been even more than the usual discrepancies in size!! Alot of sorting, pounding, cutting and cussing has ensued!

    Will make some great stories for the grand-kids, right?!

  3. Mistake, no, I don't think so. There is always a big debate about using mortar in a kiln. Some say it is the devil incarnate others laud it like a cure all. When I talked with Jim Wunch at Larkin, he was adamant for it saying that it was the way they did their big commercial work. My old Prof., Vince Pitelka was just as strongly against it. My main idea of using it sparingly is that I may need to move the kiln in a few years. It will cut down on the grinding to reface the brick.

  4. At this point, I'd be all for cutting down on any future grinding!! We've ground every side of every hard brick we've used not counting the arch!! If there's another kiln in my future, I'm planning on buying new bricks or not building one (yeah, I say that now!)

    My husband reminded me why we couldn't saw the soft brick down for my header course (that's a great solution, btw!) Unfortunately our height mis-match was the opposite of yours, the hard bricks were a tad taller than the soft!! A little extra mortar seemed like the right fix!