Question about boiling green wood to minimize cracking/warping

[Kalia Kliban]

Here in northern CA we're lucky to have regular access to madrone. While it's glorious to turn, it's difficult to dry intact since the wood warps and wiggles a lot along the way. Boiling, steaming or pressure-cooking the wood seems to stabilize it. I've heard folks mention that one should use a "non-reactive" pot for this, but it's unclear what reaction I'm trying to avoid. For example, I've successfully used steel, stainless steel and aluminum pots for this. Are there any woods for which aluminum would _not_ be appropriate? And are there other woods for which this process would be useful? I'll certainly experiment with olive next time I get some fresh.

 

[Richard Coers]

If you boiled oak in a steel pot, it would likely come out black. I have no experience with boiling, but I know oak is very reactive. My hands turn purple and little bits of steel wool can produce black spots.

 

[Dennis J Gooding]

Richard is correct. Madrone, like oak has a high tannin content which reacts with iron to produce a black compound. Even enameled steel pots are not safe if they have any pitting of the enamel coating.

 

[robo hippy]

Stainless steel, or galvanized pots/horse troughs would be best. Dale Larson up in Portland boils all of his madrone. He did a demo for the club in Salem and I told him it looked really weird because it was actually round... I turn a lot of madrone, and like mine to warp. I prefer spring harvested trees, turn to 1/4 inch thick, round over rims, wrap the rim in stretch film, then start drying on the concrete shop floor. Up on wire racks after a couple of days. Dry in a week to 10 days max. Some times I will go to 5/16 thick. Summer and fall harvested trees tend to crack more. Other than that, what I didn't like about the boiled bowls was that it tends to muddle the colors together. I like the colors in the unboiled bowls better. I guess I could add that it was, to me, a lot of extra work and cost when making bowls...

robo hippy

 

[Tom Hansen]

How much spalting or mold do you experience when wrapping the rims? I have a copy of an article Dale wrote that details the entire process if you're interested Kalia.

 

[Kalia Kliban]

Stainless steel, or galvanized pots/horse troughs would be best. Dale Larson up in Portland boils all of his madrone. He did a demo for the club in Salem and I told him it looked really weird because it was actually round... I turn a lot of madrone, and like mine to warp. I prefer spring harvested trees, turn to 1/4 inch thick, round over rims, wrap the rim in stretch film, then start drying on the concrete shop floor. Up on wire racks after a couple of days. Dry in a week to 10 days max. Some times I will go to 5/16 thick. Summer and fall harvested trees tend to crack more. Other than that, what I didn't like about the boiled bowls was that it tends to muddle the colors together. I like the colors in the unboiled bowls better. I guess I could add that it was, to me, a lot of extra work and cost when making bowls...

robo hippy

Any thoughts about aluminum? I have permission to co-opt my husband's old aluminum brewing kettle which is big enough for moderate loads of bowls. OR I could go out and plonk down some cash for a steel crab pot.

 

[Hugh]

Kalia,
I have used a enameled pot for my first try at boiling Madrone wood.
Chuck Q used to use a galvanized water trough. He cooked outside, with a wood fire under the trough. Until he tried to burn the hillside while he went to lunch one time. CalFire put the fire out. I would worry about galvanized as if the coating gets too hot, it gives off Zinc fumes, which are not good to breathe.
I have used a galvanized garbage can for a bit also. Outside. Usually, the garbage cans are a bit thin and will burn out on the bottom.
Never had a problem with the iron in the pot coloring the wood.
I finally got my stainless steel pot. Before you go purchase something.....make a trip to Maselli's on Lakeville Highway in Petaluma. Go for a walk in the yard. See what they have available.
I paid a bit under $300 for my nice SS pot. A lid would be nice, but a piece of plywood works for that. Just helps keep the heat in.
Save the colored water for your weavers in the area. Nice dye for wool.
Are the steel crab pots stainless?
I have heard of people using a 55 gallon drum for boiling also. But that would be made of steel. Not sure of the effect on the wood.

 

[Kalia Kliban]

Kalia,
I have used a enameled pot for my first try at boiling Madrone wood.
Chuck Q used to use a galvanized water trough. He cooked outside, with a wood fire under the trough. Until he tried to burn the hillside while he went to lunch one time. CalFire put the fire out. I would worry about galvanized as if the coating gets too hot, it gives off Zinc fumes, which are not good to breathe.
I have used a galvanized garbage can for a bit also. Outside. Usually, the garbage cans are a bit thin and will burn out on the bottom.
Never had a problem with the iron in the pot coloring the wood.
I finally got my stainless steel pot. Before you go purchase something.....make a trip to Maselli's on Lakeville Highway in Petaluma. Go for a walk in the yard. See what they have available.
I paid a bit under $300 for my nice SS pot. A lid would be nice, but a piece of plywood works for that. Just helps keep the heat in.
Save the colored water for your weavers in the area. Nice dye for wool.
Are the steel crab pots stainless?
I have heard of people using a 55 gallon drum for boiling also. But that would be made of steel. Not sure of the effect on the wood.

I forgot about your recommendation for Maselli's. I'll check them out. Seems like there's enough madrone crossing my path that I should have my own cooking rig for it. Do you think that's something Bataeff Salvage might have? It's been ages since the last time I went out there.

 

[Kalia Kliban]

Nobody seems to be responding about aluminum for this purpose. Would it be a problem for tannic woods? I've never noticed the aluminum parts on my lathe reacting or discoloring, and aluminum pots are a lot cheaper and lighter than steel. A local restaurant supply place has heavy-duty 80-quarts stock pots for $110.

 

[Brian Gustin]

I don't know enough about how aluminum might react with wood , but I am quite familiar with aluminum and what happens to it in various conditions (30 plus years in small engine repairs) -- So.. I'd think, unless you regularly clean out and rinse the pot after each use, you might find aluminum very quickly corroding - if you see white powder on your aluminum, it's corroding.. Acidic water (which I imagine might happen from boiling some woods) can also eat aluminum (muriatic acid makes quick work of it, matter of minutes it can eat a hole right through a typical pot) so I'd want to know more about what the water becomes during and after boiling the wood in question before going for a $100 aluminum pot..

 

[Glenn Lefley]

I don’t think aluminum affects tannin. Correction I just saw an article in Canadian woodworker talking about boiling madrone and it said you should look for a large aluminum or stainless steel pot.

 

[Kalia Kliban]

I don't know enough about how aluminum might react with wood , but I am quite familiar with aluminum and what happens to it in various conditions (30 plus years in small engine repairs) -- So.. I'd think, unless you regularly clean out and rinse the pot after each use, you might find aluminum very quickly corroding - if you see white powder on your aluminum, it's corroding.. Acidic water (which I imagine might happen from boiling some woods) can also eat aluminum (muriatic acid makes quick work of it, matter of minutes it can eat a hole right through a typical pot) so I'd want to know more about what the water becomes during and after boiling the wood in question before going for a $100 aluminum pot..

This is very helpful, thank you!

 

[Hugh]

I forgot about your recommendation for Maselli's. I'll check them out. Seems like there's enough madrone crossing my path that I should have my own cooking rig for it. Do you think that's something Bataeff Salvage might have? It's been ages since the last time I went out there.

When I went to Bataeff Salvage, they did not have the stainless steel selection that Maselli's had. But, that was many years ago. The stainless steel pot will last forever basically. Is 80 qt. large enough? If you get a nice truck load of Madrone, how many times will you have to run the boiling process? How much propane will you burn with each boiling? My large pot is about 40+ gallons or so. 22" diameter. I understand the weight problem as mine weighs in at 77 pounds.
Think of the terrific day of visiting both salvage places.......what fun. Take a lunch. As far as I am concerned.....Maselli's is a dangerous place.....so much to look at.

Question: Have you purchased a burner yet? Did you get a pot with it? Maybe a turkey fryer pot? Is it aluminum? Maybe try it?

 

[Mark Jundanian]

How much spalting or mold do you experience when wrapping the rims? I have a copy of an article Dale wrote that details the entire process if you're interested Kalia.

Tom, how about sharing that article for the rest of us?

 

[Glenn C Roberts]

I would go to Good Will or a garage sale and buy an aluminum cooking pot for a buck or so and put in your favorite wood to see what happens.

 

[JeffSmith]

This is very helpful, thank you!

I don't know enough about how aluminum might react with wood , but I am quite familiar with aluminum and what happens to it in various conditions (30 plus years in small engine repairs) -- So.. I'd think, unless you regularly clean out and rinse the pot after each use, you might find aluminum very quickly corroding - if you see white powder on your aluminum, it's corroding.. Acidic water (which I imagine might happen from boiling some woods) can also eat aluminum (muriatic acid makes quick work of it, matter of minutes it can eat a hole right through a typical pot) so I'd want to know more about what the water becomes during and after boiling the wood in question before going for a $100 aluminum pot..

Nobody seems to be responding about aluminum for this purpose. Would it be a problem for tannic woods? I've never noticed the aluminum parts on my lathe reacting or discoloring, and aluminum pots are a lot cheaper and lighter than steel. A local restaurant supply place has heavy-duty 80-quarts stock pots for $110.

I've been boiling madrone, maple, and, once in a while, oak for almost 15 years in a very large, heavy aluminum stock pot - about 24" dia x 24" high. It has never been a problem. There's absolutely no sign of corrosion and the only sign its been used for wood is a light coat of the red extractives that are common with madrone and maple both. I use a propane jet burner to heat it and, when roughing and coring I get it going first thing in the morning and go as long as possible roughing and chucking the blanks into the pot until I'm either done or can't keep going (then start again the next morning). It has had a lot of use.

There's also been no sign of discoloring of the wood I can attribute to the aluminum pot. I do make certain to keep the boil up continuously, ensure that all blanks get at least a couple hours in the pot, and pull them when the pot is still hot. Some people prefer to let the pot cool with the blanks in the water, I do not. I pull them hot, stack them on the shop floor with their rims verticle so they can cool and surface dry (a day or so). When surface dry I restack rims down, stickered to sit for a couple of days before finally stacking on wire shelves to fully dry. I've found that if I leave them in the pot to cool before pulling they are more prone to mold while drying. I do spray with a boric acid solution before final stacking to keep mold and critters at bay...

 

[Tom Hansen]

Tom, how about sharing that article for the rest of us?

After more posts it seems Kalia had more specific questions than this covers but here it is. I just finished turning my first chunk of madrone today. Ridiculous how nice of a finish I got with shear scraping. Is a timely thread for me as I was wondering if I should use only stainless or aluminum.

 

[Dennis J Gooding]

I have used aluminum successfully. I expect that enameled steel would be fine if there are no cracks or pits in the enamel. However, I had a failure a couple of months ago with an old enamel pot. As for stainless steel, it comes in many flavors, some which may not be suitable. Do a test run with scrap wood if there is any doublt

 

[robo hippy]

Well, not being from your area, I have no sources. Up here, If I wanted a big aluminum pot, I would go to a place that sells used restaurant equipment. If nothing else, put a couple of small pieces in the pot and see what happens.

As for mold, When I tried to wrap some maple, it looked like it had a bad case of measles except the spots were dark grey. Most of the maple is pretty stable.

robo hippy

 

[Karl Loeblein]

Use at your own risk, but I use an inexpensive extra large stainless steel bowl on a turkey fryer. Google will provide many sources like this one for $15:

https://www.webstaurantstore.com/ch...z3FFTwZtu8EFo9U9Fh6ny-Eg2NyLa6XBoC4SMQAvD_BwE

 

[JeffSmith]

Well, not being from your area, I have no sources. Up here, If I wanted a big aluminum pot, I would go to a place that sells used restaurant equipment. If nothing else, put a couple of small pieces in the pot and see what happens.

As for mold, When I tried to wrap some maple, it looked like it had a bad case of measles except the spots were dark grey. Most of the maple is pretty stable.

robo hippy

Found mine in the scratch and dent section of a restaurant supply store in Seattle pretty cheap. Its about 1/4" thick - they offered a lid but. it was new and not dented, but they wanted more than the pot was marked...I passed

 

[Tom Willing]

Here in northern CA we're lucky to have regular access to madrone. While it's glorious to turn, it's difficult to dry intact since the wood warps and wiggles a lot along the way. Boiling, steaming or pressure-cooking the wood seems to stabilize it. I've heard folks mention that one should use a "non-reactive" pot for this, but it's unclear what reaction I'm trying to avoid. For example, I've successfully used steel, stainless steel and aluminum pots for this. Are there any woods for which aluminum would _not_ be appropriate? And are there other woods for which this process would be useful? I'll certainly experiment with olive next time I get some fresh.

Hei, Kalia,

I believe Dale's boiler is a salvaged stainless steel water tank our of a sailboat, at least that's what I remember him saying when I asked him. I boiled a round in his boiler once and have boiled quite a few in 21"ø aluminum kettle fired by a propane burner. I have never had reactive problems, but I know regular steel kettles (canning kettle with cracks in the enamel will turn your madrone a pretty yucko grey color. I am roughing and boiling tomorrow as it turns out.

Be safe, stay healthy.

 

[Tim Tucker]

Stainless steel, or galvanized pots/horse troughs would be best. Dale Larson up in Portland boils all of his madrone. He did a demo for the club in Salem and I told him it looked really weird because it was actually round... I turn a lot of madrone, and like mine to warp. I prefer spring harvested trees, turn to 1/4 inch thick, round over rims, wrap the rim in stretch film, then start drying on the concrete shop floor. Up on wire racks after a couple of days. Dry in a week to 10 days max. Some times I will go to 5/16 thick. Summer and fall harvested trees tend to crack more. Other than that, what I didn't like about the boiled bowls was that it tends to muddle the colors together. I like the colors in the unboiled bowls better. I guess I could add that it was, to me, a lot of extra work and cost when making bowls...

robo hippy

THIS makes a lot more sense to me than the creation of an entire other hobby...That of tending a boiling pot over a fire outdoors....I am guessing ( but would like your confirmation...)that the place you are storing them is cooler, and your humidity norms are lower than the rain forest I live in. And, being as they are directly on the concrete, there may be some drawing out moisture from the wood into the concrete?

 

[robo hippy]

We do have a very mild climate. Even in summer time, it can get up to 90 to an occasional 100, but it cools off to mid 50s to 60 at least during the night. You have high humidity in the summer where you are. Drying is as much of an art as the turning, and selling, if you do that...

I do think the concrete floor is a good start, and away from any wind and sun light. There is always some water in concrete unless they put a vapor barrier under the slab...

robo hippy

 

[Tim Tucker]

BTW...I am still "experimenting" with the alumina based dessicant bead and very encouraged with the results thus far.....

 

[Lars Hansen]

@Tim: Do keep us informed, please!

 

[Tim Tucker]

Will do Lars!

 

[Glenn C Roberts]

Tim, why did you choose alumina over silica? Silica can be moisture indicating, can alumina?

 

[Tim Tucker]

Either can have a color change indicator added. But the alumina based will adsorb 40% of its weight . The silica based adsorbs 25%

 

[John Tisdale]

I've boiled every piece since 2008 except mesquite - don't do bowls, only hollow-forms. My pot is aluminum - I was looking for the largest available and it just happened to be al. The dimensions are 24" dia and 24" tall.
I "rough" a green log to dimensions that allow me to re-turn to round. Assuming a radial turn (face grain), a 20" diameter walnut requires a wall thickness of almost 1.5".

• Turn the outside to it's final shape - don't think you can refine after dried
• Hollow the inside to a wall thickness that allows for shrinkage - read Bruce Hoadley. Tip: wrap with plastic pallet wrap - minimizes the little cracks
• Boil asap - put in the log, fill with water, and start the fire. Sash weight with 3" cords attached, will keep from floating
• I boil about 3-hrs - you have to constantly watch in case of flame-out - destroying the neighborhood is bad form
• Turn off and let it cool - do NOT remove from the pot when hot - duh! The cords will allow you to remove the sash weights - even then, if a large hollow-form, get ready for a struggle.
• My drying room has a dehumidifier running 24/7. The first stage of drying is the most difficult - I put my stuff in a sealed double-strength cardboard box and rely on the cardboard to retard the drying. A 2" computer fan on maybe a 12" length of PVC, PULLING air out of the cavity assures uniform drying. I keep it sealed from full-saturation to 20% MC, usually 3-months or more. After that I can take it out and be more aggressive. Acccording to Gene Wengert, VA Tech Forestry, full-saturation to 20% is where cracking losses occur.
• Then back to the lathe. First step is to re-true the faceplate-tenon (can't imagine using a chuck without monster steady-rest)
• If you were thinking boiling reduces warping, sorry - it has zero affect. Secondary turning is more demanding than the roughing.
• Regarding pot material, I don't think it matters. It's a guarantee that your pretty turning will come out of the pot an ugly grey or maybe darker. I found that to be superficial - the secondary turning removes the ugly. I've boiled boxelder - when returned the reds are just a vibrant...for a while.

 

[Jeffrey Corwin]

I've boiled every piece since 2008 except mesquite - don't do bowls, only hollow-forms. My pot is aluminum - I was looking for the largest available and it just happened to be al. The dimensions are 24" dia and 24" tall.
I "rough" a green log to dimensions that allow me to re-turn to round. Assuming a radial turn (face grain), a 20" diameter walnut requires a wall thickness of almost 1.5".

• Turn the outside to it's final shape - don't think you can refine after dried
• Hollow the inside to a wall thickness that allows for shrinkage - read Bruce Hoadley. Tip: wrap with plastic pallet wrap - minimizes the little cracks
• Boil asap - put in the log, fill with water, and start the fire. Sash weight with 3" cords attached, will keep from floating
• I boil about 3-hrs - you have to constantly watch in case of flame-out - destroying the neighborhood is bad form
• Turn off and let it cool - do NOT remove from the pot when hot - duh! The cords will allow you to remove the sash weights - even then, if a large hollow-form, get ready for a struggle.
• My drying room has a dehumidifier running 24/7. The first stage of drying is the most difficult - I put my stuff in a sealed double-strength cardboard box and rely on the cardboard to retard the drying. A 2" computer fan on maybe a 12" length of PVC, PULLING air out of the cavity assures uniform drying. I keep it sealed from full-saturation to 20% MC, usually 3-months or more. After that I can take it out and be more aggressive. Acccording to Gene Wengert, VA Tech Forestry, full-saturation to 20% is where cracking losses occur.
• Then back to the lathe. First step is to re-true the faceplate-tenon (can't imagine using a chuck without monster steady-rest)
• If you were thinking boiling reduces warping, sorry - it has zero affect. Secondary turning is more demanding than the roughing.
• Regarding pot material, I don't think it matters. It's a guarantee that your pretty turning will come out of the pot an ugly grey or maybe darker. I found that to be superficial - the secondary turning removes the ugly. I've boiled boxelder - when returned the reds are just a vibrant...for a while.

John,

I just watched a video of a demonstration that you gave the Dallas Area Woodturners. I was impressed by the apparent ease of turning that you achieved with the custom-made tool holder you used in the hollow form turning. Would you be able to post either the plan for that tool holder, a photo of it, or information on where I could get one? Thanks, Jeff

 

[John Tisdale]

John,

I just watched a video of a demonstration that you gave the Dallas Area Woodturners. I was impressed by the apparent ease of turning that you achieved with the custom-made tool holder you used in the hollow form turning. Would you be able to post either the plan for that tool holder, a photo of it, or information on where I could get one? Thanks, Jeff

Happy to share. I have my tool-rests made at a machine shop - you would need to do the same.
There are a lot of nuances associated with using my internal rest - my technique comes with baggage:

• I'm 6' tall and the lathe center is about 53" off the ground. It is on 2x8 glue-ups that extends the footprint and allow a platform which puts me at the normal 44" for doing the outside turning.
• I have high-bright LEDs on the rest lighting up the interior of the hollow-form
• I used the large Rolle Munro with the standard shaft for most pieces
• To my thinking, my technique is great for large hollow-forms with 3"+ openings - that's all I do.
• Not sure it makes sense for a woodturner that does a variety of work or for a woodturner working out of a garage..

Again, happy to explore if it makes sense for your situation.
John

 

[Jeffrey Corwin]

Thanks for describing the constraints. I’m not ready to tackle hollow forms of the size you make, and may never be. I am mostly interested in the overall shape of the internal portion of your tool rest. I was intrigued by how effective it seemed to be, but not able to see the internal part of the rest in the online video.
Do you think that your tool rest might still be useful if its dimensions were reduced to fit inside of hollow forms with smaller openings?

 

[John Tisdale]

Do you think that your tool rest might still be useful if its dimensions were reduced to fit inside of hollow forms with smaller openings?

I don't know - haven't given it much thought. Perhaps the question should be: Is there anyone smart enough to figure it out? Of course that answer is "yes" but the caveat is: does that person have the desire to work through seriously stupid mistakes?
The primary constraint is: what minimum hole size? Mine is about 3.25" diameter, large enough for my hand. The stack-up of bar, plate, tie-wrap spacing is a bit is about 1.375" That gives wiggle room for maybe .25" clearance and allows for a 3/4" tool with the cutter at 3/8".
Let's say you want to do hollow-forms with 2" holes. Would a .5" thick plate, maybe 1" wide, provide the stiffness? Maybe. Or you could go 5/8" thick (no bar, just plate). With a trapezoidal cross-section, I would guess it would work. My rest has threaded holes on both sides for the pivot pin - that was dumb - one side is all that is needed.
I've been using "flash light bulb LEDs" which are huge - there are some minis out there with encapsulated emitters that will withstand the rather brutal environment inside the form being hollowed - I'll be investigating in the coming weeks.

Actually, the necessity of a toolrest that goes deeply into the work may not make sense on smaller pieces. Perhaps a 3/8" platform that goes in maybe an inch or two WITH LED's and, most important, with THREADED HOLES to allow at PIVOT PINS at the opening

It's easy to have grandiose ideas with somebody else's money. They again, you may own a machine shop and work out of scrap - or maybe a brother-in-law machinist.

 

[Jeffrey Corwin]

Thanks for the photo and the additional explanation, John! Those helps me to get a much better understanding.