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Gordon Vizecky
09-27-2010, 12:38 PM
First the story and then, I’ve got couple questions for the bowl boilers out there.

I don’t have pictures at the moment but I will post soon.

I’m in the process of finishing my boiler. I couldn’t use an oil drum because some of my bowls would be too big. After racking my brain for a while on a suitably sized alternative I decided I would fabricate one myself, and found some cold rolled 12ga on craigslist for $30 a sheet so I picked up two. The 12ga was thicker than I wanted but the price was right and I figured I would just make a wood bending form and clamp in place until I could get it tack welded. What could go wrong?

The sheet was ripped in half with the torch and cleaned up with the grinder (so far so good). With a bit of effort it was bent into enough of a “U” shape that a nylon ratchet strap would go around. Long story short the metal was much tougher than anticipated and after a two hour fight I was standing in my driveway breathing heavily and holding a broken ratchet strap. The piece of steel however mocked me rocking to and fro like some evil invisible rocking horse.

Back to Craigslist, a sheet metal fabricator was located and for a $30 he would run it through his slip roller and weld it together for me (Score!).

Now the lid and bottom need to be cut out and the bottom welded on (maybe this weekend) and then it is off to the boiling.

Anyway since my biggest bowl is a theoretical 24” and Steven Russell recommended 6” of additional space for circulation I was targeting a 30” dia. boiler. A full size sheet of steel is 96” on the long side which would yield a 31” dia. boiler (close enough). I used to do a bit of all-grain brewing so heating up liquids on propane burners was familiar enough, but the deceptive capacity of the cylinder was nagging at the noggin (time to do some math). Holy misjudgment Batman! Spitting distance from 80 gallons if I made it 24” high. …lets see get out calculator 8 * 79….632 pounds if it were full of water!! Considering the BTU requirements to heat up that much water I could see in my future, a second mortgage to pay the LP bill.

I thought about it for a bit and decided why did I have to have immersion? Why not steam the bowls like steaming broccoli? It would take far fewer BTUs to heat up 5-10 gallons of water and even at a pretty hard boil I wasn’t going to lose much more than a gallon per hour. I could put a rack in the pot a couple inches high and a lid on top and I should be golden. It would even allow me to steam for the appropriate time and when the cycle was done I could just leave them in the kettle to cool down, reacclimatize and pull them out and paper wrap them the next day.

Anyway sorry for the long post, here are my questions:

How profound are the color changes in walnut with the boiling process? (I’ve seen reports that the surface color changes a bit but it is turned away during finish turning, what can I really expect?).

Anyone else steam like this or does everyone boil?

Do you keep bowls in plastic bags until turning day or how do you store them until you have enough to cook?

This kettle is going to be pretty heavy (the steel weighs 140# per sheet) and I still need to find a place to store it but, I’m excited about getting it fired up.

Thanks for any advice you have.

Gordon

Frank Van Atta
09-27-2010, 3:25 PM
I have been pressure cooking green wood for years - lots of steam and pressure, too. I find that color changes, usually darkening, are consistent throughout the piece and not just on the surface. The other result is that the wood is usually harder after pressure cooking.

Gordon Vizecky
06-02-2011, 10:05 PM
I was all gung ho on the bowl steaming thing but then it seemed like the rough bowls weren't really showing any signs of cracking so I didn't push on getting the project done before winter (mistake). Anyway I'm now the proud owner of 8 20"+ bowls and a host of smaller ones that are cracked terribly. Apparently even with anchor seal and storing them on the floor in a quiet corner of the basement, the desert dry of Minnesota winter pulled out the moisture too fast.

I still had a bunch of walnut left and didn't want to have more crack so I finished up the boiler, roughed out some bowls and took it on a maiden voyage of sorts tonight.

I used bricks to keep the bowls out of the water, poured in 9 gal of water waited until I had steam coming from under the lid and I steamed everything for 2 hours.

It was quite windy so I ended up using my garbage cans and some flagstones as a wind break.

I'll pull the bowls out and anchorseal them tomorrow morning. Hopefully no cracks as they dry.

The pic showing the roughed bowls was before the last 21" went into the pot.

I'll post an update as to whether I get any cracking later.

Gordon

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