PNW Pizza

[Lotus19]

Hi all! Just wanted to introduce myself and say what a great forum this is. So many great builds, with tons of helpful tips and tricks. I've attached some pics of my build.

I'm in Kingston, WA and am currently building a 32" oven. Plan on doing the tried and true homebrew cast over sand method. Using weep holes, a layer of mosaic tiles, 2" calsil and 2.5" firebrick puts my oven floor right at 50", which feels good to me (I'm 6'2").

I have my floor bricks, but I'm having a heck of a time finding 2" calsil board. I don't really want to do 4" of vermiculite, because that will make my floor height a bit too tall. I tried contacting DI, but no response. Anyone know of a local supplier?

Thanks, Joe

[Lotus19]

[UtahBeehiver]

Check with or PM JR Pizza or Deejayho both are from the Seattle area on CaSi source.

[Jeff B]

Hello fello PNW'er. Your stand is looking good! I'll be following your build.

Jeff in Gig Harbor

[Lotus19]

Decided to scrap the CaSil board, and went with 4" of Vermiculite (5:1). Keep covered or uncovered for the next week? I've read both... Thanks!

[david s]

I guess it depends a bit on your weather, but as there is so much free water left in the vermicrete the risk of it drying out too fast is limited. Give it plenty of time to dry out though and cover it if it looks like rain.

[Lotus19]

Thanks, David. Temps for the next week are in the high 70's, so not too concerned about it drying too fast. I'll leave it uncovered...

Should I keep it in the form the entire time?

[david s]

I’d be removing the form work after a couple of days. If left too long sometimes the formwork doesn’t come away from the casting cleanly.

[Lotus19]

Anyone know any good polypropylene burnout fiber suppliers in the states?

[Lotus19]

Anyone know any good polypropylene burnout fiber suppliers in the states?

Bueller... Bueller... I have all my ingredients to cast my dome this weekend, except for the thin poly fibers. Can anyone provide me with a source, or are they really that necessary?

Thanks,

Joe

[david s]

All the castable refractory that I’ve seen contains burnout fibres which reduce the possibility of steam spalling which can create devastating failure. Although the most important factor is to follow a slow firing schedule. Some home builders have got away with not adding them, but it’s risky if you don’t.
Fibres designed for concrete reinforcement can be used, but only the short really fine polypropylene fibres should be used. Try Sika Radmix 48/19 or equivalent. They have the added bonus of holding the mix together, once they are dispersed evenly, making placement easier.

[Sixto]

i found some on Fleabay by searching for "polypropylene fiber concrete"

[Lotus19]

Was able to find the poly burnout fibers on Ebay, so I was able to finally cast my dome this weekend!

Filled the space with as much junk as I could and still ended up using almost 200 lbs. of fine play sand. Once I got the water consistency right, the sandcastle went rather smoothly. I did add some clay to the sand as well.

Dipped my newspaper on a water/flour mixture and covered the sand dome.

Mixed up the 3:1:1:1 homebrew, with a handful of poly fibers per 5 gall bucket. Found 1.6-1.7 parts water was the sweet spot. First batch was just a bit dry, but still workable. Remaining batches were a little wetter, but did not sag. I found this part of the build pretty easy and fun. Used a technique of smashing softball sized balls of the homebrew against the dome, using a combination of slapping and karate chopping the mix. Once finished, covered with damp towels and plastic wrap.

[Lotus19]

The application of the homebrew seemed to go too easy and I was sure I'd jinx myself. Luckily, when I removed the sand I found the the cast went really well. A few tiny voids on the inner dome and a couple larger ones on the face of the entry, but they'll get patched tonight when I smooth over with some of the "peanut butter" mix. Once I'm done with my patching, I'll re-mist everything and wrap in towels/cling wrap for a week. Hopefully cast the gallery next weekend.

[david s]

Excellent work, thanks for sharing. Keep the pics coming so others can benefit.