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Mark Horst

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  1. Castable Recipe For Pizza Oven

    So, I've finally got around to posting the results of my pizza oven project... From what I've heard the ratio of the dome height to the door height is pretty important for getting a natural draft going so I went with the dimensions of a commercial oven maker. The interior height of the dome is 16 inches and the height of the door is 10.5 inches. It just so happens that a five gallon bucket has a diameter of about 10.5 inches... so that's what I used for an arch form. I used sand as the form for the dome and covered it in wet newspaper before slapping on the castable. I used the recipe listed above for the castable. Once it was dry I dug out the sand and let it dry for a few days. Then started with a very SMALL fire in the doorway to dry and cure the castable. I used the lid from an old electric kiln for the base and then a layer of firebrick to hold heat. I used firebrick for the arch and the first two layers of the dome just to save on the amount of castable that I had to mix. The arch was a little tricky because I didn't have any arch brick, but it's held up pretty well. The idea for a face on the front came from a pizza oven that I have used in PA at the Union Project wood kiln near Pittsburgh. If you have any questions let me know. You can also see more pictures on my facebook page www.facebook.com/markhorstpottery It makes pretty good pizza... and only cost me about $100 Cheers, Mark
  2. Castable Recipe For Pizza Oven

    I've built the pizza oven... Hopefully I'll soon get pictures off my camera and post them with some more details about my wood fired pizza oven.
  3. I've got a bunch of leftover hard brick from an old kiln that I tore down and want to build a pizza oven in my backyard. I'm planning on using brick for the floor and the door, but want to use castable for the dome. Does anyone have experience with this? I've found this formula for kiln castable, but was wondering if there are any specifics that I need to keep in mind when thinking about pizza as opposed to pots. 2 Fireclay 2 Grog 2 Sawdust 1/2 Alumina Hydrate 1/2 Portland Cement Thanks in advance, Mark
  4. Problems With Clumping In Glaze

    Thanks for your replies. Ben, I'd be interested in the calculations that you mentioned to replace the Neph Sy and Lithium... Thanks, Mark
  5. I'm having some trouble with one of my glazes clumping. It is not a settling problem because it mixes back up fine, but with the exception of pebble sized clumps of something. I'm assuming it's silica because once fired the places where these clumps end up are clear and don't have any color. It's like little pebble sized clumps that feel like sand when I rub them between my fingers. In the past I've sieved the chunks out, but am worried that I'm tampering with the formula... here's the formula: Hirsh Satin Matte Blue 9 Lithium Carb. 35 Fint 32 Gerstley Borate 4 Neph Sy 4 EPK 17 Whiting 2 Bentonite 1.5 Copper Carb. It's a cone 04-02 glaze... any thoughts would be helpful. Oh, and it hasn't frozen, so I'm sure it's not that. Also, it seems to start happening about 4 months after it is originally mixed up. Thanks, Mark
  6. Electric Kiln Conversion To Propane

    I just unloaded my first firing with my new converted electric kiln. I'm using propane and a weed burner. I got it up to cone 10 in about 9 hours. I used a pyrometer and cones to figure temperature, but as other posters have said it's pretty hard to measure how much gas you are actually putting into the kiln. I do it mostly by sight and sound of the burner, and smell of what is coming out of the chimney as well as flame speed observed through the peep holes. I also add wood and soda into the kiln which i had some problems with this time because I didn't have enough air to fully combust the wood and had to make some adjustments during the firing to get more air. Make sure you have enough propane on hand to finish the firing. I used a 100gal tank and used about 1/3 of it. So if you plan on using the normal gas grill tanks make sure you have two of them so you can switch it if you run out. Also, I had some trouble keeping the weed burner lit during the first two hours of the firing because it was a little breezy and since it doesn't have any safety stuff on it I had to monitor it until it got to red heat and could reignight itself if the wind blew it out. My kiln is a little different than other converted kilns because I had a bunch of hard brick laying around that I used for the floor and the first two courses, then I set the electric (skutt 1018) kiln on top. The burner port and wood stoking port are in the first two courses. Those bricks are laid endwise with wadding filling the gaps. Hopefully the attached picture helps a little. Let me know if you have any other questions and I'll throw in my 2 cents. Mark
  7. Even Wax On Bottoms Without Hazards?

    I've found that my wax resist gets those little balls of wax built up if I use the same container for a long period of time. Some of the wax starts to dry and then clumps together. To remedy this I use a small disposable container to hold a small amount of resist and when it is empty I just fill a new container. Also, I use foam brushes to apply wax resist. This gets an even coat and they are really cheap so you can use them for a day or so and then throw them out. This also alleviates the problem of stray bristles getting wax where you don't want it to go. hope that helps, Mark