Microwaving boiled bowls........?

[Doug Rasmussen]

I've had good luck microwaving small green bowls. The ones I've done were finish turned to size then microwaved and lightly sanded after drying. In difficult wood a couple cracked immediately after turning before I could get them to the microwave. My hope is the boiling will eliminate the post turning cracking with madrone and holly.

Somewhere on one of the turning forums a poster implied boiled wood tends to air dry faster than unboiled.

My question is, are there any issues with rough turning, boiling and finish turning, then off to the microwave? If the theory of faster drying of boiled wood is valid then my assumption is microwaving would also go faster.

As to boiling....if you have a spouse does boiling in the family kitchen rank right up there with washing greasy machine parts in the dishwasher? Or, is it a fairly odorless, clean operation? I suspect I'll have to do it on the barbeque in the back yard. Stainless container or will aluminum be okay?

Another question, do you put the wood in boiling water or bring the cool water up to a boil after the wood is put in? Some "boilers" also suggest letting the water cool before removing the wood, is this necessary?

 

[olaf Vogel]

My brief foray into these two technique gave some insight. (also did a ton of reading on the commercial uses and research papers to support them - I'll see if I still have the papers)

Both methods seem to break down the lignins in the wood. So they essentially do the same thing. I have to assume that heat and time are the main ingredients in achieving this.

Boiling wil add moisture.
Nuking will remove moisture.

My microwave is too small for most of my work, so I moved on to boiling.

So to your questions:
- you "might" be able to dry a bowl faster after boiling, since the internal tension is lower/gone. So you can dry more aggressively. Have not tried an A/B comparison
- I have not gone through 4 step of Turn, Boil, Turn, nuke. Sounds like too much effort to me. Someone around here had a good saying: "Maximum effort doesn't always get you best results"
- Lobster pots are huge and can handle big bowls, but usually require a BBQ type burner. Heck a BBQ will work - if it can handle the weight. A full lobster pot is really heavy.
- Any container will do. Large pots are AL, since SS is much more expensive.
- I just drop the bowls in when its boiling. There's no point bring the temp up slowly, it will just soak the wood. Drop in as many as possible, then add a big rock.

My next experiment is steaming. That can be any size, less moisture, higher temps.
For commercial lumber, steaming is used. Rarely nuking or boiling.

Good luck

 

[Mike Johnson]

I have pressure cooked a number of green wood blanks and depending on the wood
type you will have some odor that releases from the heated wood. Since you are starting
with green wood you really won't add any moisture to the wood blank. The wood blanks
seem to dry quicker after they have been boiled. Having a number of wood blanks and rough
turned bowls simplifies the process over time.

 

[hockenbery]

Doug,
Madrone - I have turned very little madrone. The wet madrone I turned thin and watched it move.
Dale Larson turns really nice bowls and always boils the madrone after roughing.

This article is how Dale does it.
http://www.serioustoolworks.com/wood-turning-a-madrone-bowl-01.php
Note he uses a stainless steel pot.

Holly - I have turned lots of American and dahoon holly. I did not find it difficult to dry but these were all east coast trees and sometimes west coast woods behave differently

Madrone needs special attention either thin and air dry or boil.
Have fun.

 

[robo hippy]

I love warped madrone, and the more it warps, the better it sells. I don't like boiling because it is way more work, and it muddles the colors a bit. I guess you could microwave the wood after boiling, but to me that is extra work/time. To thin turn madrone, get early spring trees. For reasons I don't understand the spring wood will crack less than summer/fall wood. No more than 1/4 inch thick.

robo hippy

 

[JeffSmith]

Depends on the protocol you use to boil. Some swear by quenching the blanks in cold water after boiling. I prefer to pull them hot from the pot and sticker and stack them upright (bottom down) until surface dry - usually just a matter of an hour or so, let them sit overnight, then stack bottoms up with good spaces for air circulation on the floor for a week or so, then onto wire shelving to dry thoroughly before returning to the lathe when the moisture gets down to less than 12% or so.
I usually treat both Madrone and BL Maple the same way.

If I want to play with a little warping, I won't wait for full dry before going back to the lathe. Full disclosure - most of what I do doesn't fit in my microwave...

 

[Owen Lowe]

I have pressure cooked a number of green wood blanks and depending on the wood
type you will have some odor that releases from the heated wood. Since you are starting
with green wood you really won't add any moisture to the wood blank. The wood blanks
seem to dry quicker after they have been boiled. Having a number of wood blanks and rough
turned bowls simplifies the process over time.

Are you saying that there is nothing more in the pressure cooker than the green wood piece?
How long do you “cook” it? I’ve wanted to try pressure but just haven’t delved into it yet — and don’t really want to spring for a cooker that would accommodate an 18” bowl.

 

[Bill Boehme]

I have pressure cooked a number of green wood blanks ......

It would take a lot less boiling if the wood blanks were rough turned first rather than boiling all that wood that will just wind up as shavings on the floor.

Are you saying that there is nothing more in the pressure cooker than the green wood piece? ......

I would recommend a ham hock and purple hull peas.

 

[Mike Johnson]

Are you saying that there is nothing more in the pressure cooker than the green wood piece?
How long do you “cook” it? I’ve wanted to try pressure but just haven’t delved into it yet — and don’t really want to spring for a cooker that would accommodate an 18” bowl.

Owen,

I add enough water to float the wood blank off the bottom of the pressure cooker. The more water you have in the cooker speeds up the cooking process, I usually wait for the pressure cooker to start releasing pressure before starting the timing of the process. Larger pieces take longer to heat up all the way through. Once the cooking is done and heat is shut off I wait for the pressure to equalize in the cooker and remove the wood and add a fresh batch to the hot water and add additional water if needed and start the next batch.

 

[Bill Boehme]

Mike, what size pieces of wood are you talking about?

 

[Doug Rasmussen]

Lot s to think about here...thanks to all who replied.

I may stop at the Goodwill to see about a used pressure cooker.

 

[Mike Johnson]

Bill,

I have pressure cooked a number of round bowl blanks that just fit inside the pressure cooker,
I used an eye bolt screwed into the center to make it easier lifting them out of the cooker.
16" to 18" in diameter

 

[Dennis J Gooding]

An alternative to microwave drying for small turnings, with or without previous boiling, is to soak the piece in DNA (shellac solvent) for a few days and then let it dry. Depending on the thickness and size, the drying time will be reduced to a few days or a few weeks. The alcohol usually can be re-used several times.