Roughed Out Bowls - Paper Bag Drying Method Only or Boiling

[Tony Maness]

Has anyone had success with boiling roughed out bowls and then drying? If so, what were the steps involved?

 

[Glen Blanchard]

Tony - I am a big fan of DNA bath for 24 hours and then drying with the rough-outs wrapped in newspaper. Very, VERY little cracking and they dry fast. Here in Dallas, most are dry within a couple of weeks. I've only been turning for a couple of years so I don't have the experience of others here, but I am very happy with the DNA bath.

 

[Rob Wallace]

Drying roughed-out "green" turnings....

Hi Tony!

I think the boiling process can possibly improve the drying effects (disrupts cell membranes and possibly reduces stresses, or simply makes them more uniform), and might shorten the drying process a bit (?), but I think it is a significant added expense due to fuel costs, significant effort to do it, and time; it is not necessary by any means.

If you want to read about an explanation of the boiling process have a look at Steve Russell's web site:
http://www.woodturningvideosplus.com/boiling-green-wood.html

BTW - "DNA" is a frequently used abbreviation for denatured alcohol (methylated spirits). I occasionally use an alcohol soak immediately following wet-wood turning of some cracking-prone species (i.e trees of the Rose family, or "fruitwoods" - a misnomer because all flowering trees produce fruit), but this also adds considerable expense if used routinely; in my opinion, routine alcohol soaking also is not necessary. Anecdotal evidence suggests that this method will work with relatively "fresh" alcohol, but not when the concentration of alcohol drops to about 70% or lower (it gets diluted with each use), so if you turn a lot and this is part of your normal routine, the expense can begin to get significant - the price of denatured alcohol continues to rise (now about $ 15/gallon around here), and you need enough to cover the piece. For large turnings, this can get expensive fast.

Many turners, including me, routinely coat the piece (outside primarily; sometimes inside as well) with Anchorseal (or another similar wax-emulsion sealer) following rough turning of the piece, and then allowing it to dry slowly in a protected area. For me, this is my method of choice. Minimal follow-up time and expense is required, and this method provides good quality results with relatively few losses.

Some advocate the rough-out-in-a-paper-bag method which also works well as long as you periodically change the bag or allow accumulated moisture to leave to avoid molding the surface of the rough-out. If you are willing to keep an eye on the process, this also works very well. After I started using Anchorseal, I never went back to the paper bag method, saving lots of time, particularly when you have 20 or 30+ pieces at different stages of drying which need to be checked at critical times while drying - too much work.

I have NEVER had success in attempting to dry turned pieces in wood shavings - I've had fungus farms EVERY time that it was tried, and I will never use that method again.

Good luck with finding the method that works best for you - try several and compare the results, time, expense, and effort needed to get good quality dried rough-outs with minimal loss. Many, many woodturners go through these same procedures while trying to see what works for them - for me, boiling was abandoned fairly early-on.

Rob Wallace

 

[Bill Boehme]

I'll add an AMEN to all that Rob said.

Some turners also melt paraffin wax to paint the end grain for slowing down the rate of drying. That is fine if your are putting it on log ends or large blocks, but it's not my first chooice for coating rough turned bowls because the paraffin can soak too deeply into the end grain if the wax is too hot when applied (you know it is too hot after it is too late and you see it disappear into the end grain). Anchorseal OTOH mostly sits on the surface of the wood, BUT if you leave it outdoors in the summer sun, it also will completely soak into the wood. If you think about it, coating the wood with Anchorseal to slow down the drying and then leaving wood outdoors in the summer sun just doesn't make good sense so I won't go into detail about how I came to embrace that bit of wisdom.

 

[n7bsn]

Some excellent points made already
To draw a line under some

What works for one person might not work for another, due to wood specie, climate, conditions in your shop, etc.

Personally I only boil woods that require the stabilization it appears to provide; in my case some tropicals, Madrone (burl mostly), some fruit woods and Lilac.

Honestly I often don't bother boiling fruit, as it's just too common. I often don't boil plain Madrone either (same). But then trees grow like "weeds" around here. I have a 50 ft tall Redwood I planted 20 years ago. Red Alder can go from a sapling to mature in 20 years.

Boiling may (and probably does) marginally reduce drying time, mostly what it appears to do is reduced cracking failures.

I do (generally) get good results from bagging with chips, but people in the same climate sometimes have fungus issues, probably due to their shops being wetter then mine.

Get free wood, if it doesn't turn out, remember "There is no turning so bad it can't be burned" (Dale Nish)

 

[JeffSmith]

What works for one person might not work for another, due to wood specie, climate, conditions in your shop, etc.

I'm in the moist Pacific Northwest as well, and find boiling helps with woods prone to cracking on drying - for me that means most fruitwoods and particularly Pacific Madrone, especially burl, but I also boil even straight-grain madrone if there's even a hint of twist or swirl to the grain. Once I get going, anything that moves goes into the boiling pot. The picture is a madrone burl roughout that was boiled and a chunk of cutoff from the same piece of burl about the same thickness and dried under about the same situation. These have both been sitting in my shop for about 8 weeks.

The procedure isn't particularly time consuming or difficult, at least the way I do it - yet it seems to work. Get my prepared blanks together, setup the boiling pot (100 Qt stock pot on a propane turkey cooker). Takes about 10 - 15 minutes to get setup. Start roughing and coring the blanks, chucking the roughouts into the pot as I go. About an hour in, the pot is at a slow boil. Keep on roughing until everything is roughed out and cored. Depending on the size of the blanks, I can get 12 to 24 roughouts in the pot at the same time. If I need room, I take out whatever has been in there the longest (its usually been boiling for at least a couple of hours by then). As you might have noticed, I don't approach the process with a slide-rule and clipboard; sometimes they'll sit in the pot for several hours before being pulled out.

At the end of the day's work, pull them out, stack them on edge somewhere with good air circulation until they're surface dry. Some people quench them in cold water first, but I haven't seem a benefit. After the initial surface drying (sometimes a couple of days, they are stacked rim down with plenty of separation for air circulation on the shop floor. There they sit - checked on once in a while - until they're ready to turn. I use the smallest cores to check on MC - just turn them and let them dry and see how much they move. I've played with the idea of letting them sit in the cooling pot overnight, but have found that it seems to promote mold growth on the blanks while they're drying.

With this 'process' I haven't lost a madrone burl piece in a very long time. Perhaps a DNA soak would do the same thing, but why mess with success? If I'm roughing other species along with madrone or even maple burl, I'll chuck everything into the pot - don't know if it helps much with all of it, but it doesn't seem to hurt and I loose very few roughouts to cracking. It's just part of the roughing process for me.

 

[Dennis J Gooding]

I have used boiling only on madrone (regular and burl), which is more prone to cracking than most other woods that I work with. I find that it considerably reduces the rate of checking during drying. One negative point that I have noticed is that the boiled madrone will mold seriously if sealed up for drying, whereas the raw madrone pieces usually will not. The cost is not a factor for me, because I heat the vat with scrap wood or brush that would be burned anyhow. It is important not to use a vat made of non-stainles steel or the boiled wood will blacken from an iron-tannin reaction. DAMHIK.

Regarding alcohol drying, I use it occasionally, but only when I need to complete a piece very quickly. It reduces the drying time of rough turned pieces from months or years to a few weeks and I have not observed any increase in likelihood of checking. I also would not expect to see any decrease since the alcohol merely displaces the water in the wood and probably does not produce any chemical changes such as boiling does.

 

[robo hippy]

Boiling is just too much work for me. For most woods, and if you are twice turning your bowls, rounding over the rims, sealing, keeping in a cool place out of sun, wind, and heat will do fine. For problem woods like madrone, a different approach is needed. I turn to final thickness, let them dry and warp, then sand and finish. Trying to dry with wet shavings can be a problem because of mold, or other types of discolorations. I did hear of one turner who used cat box litter (clean of course) which worked well. Some old timers would take madrone and sink it in a pond or rain barrel for a year or so. That seemed to do what the boiling does (breaking down cell walls so that water can go out). It can mess with your wood colors, but not always in a bad way. I haven't tried the DNA method for a long time. On my green turned bowls, it made no difference at all in drying time (7 to 10 days), warping, or cracking. I don't think I have ever done twice turned bowls. Rims seem to be the most likely to crack areas. Turn out ALL cracks and defects if you can, round over the rims, and I use stretch plastic film (Office Max or any shipping supply place), and put several wraps over the rim to put it under a little compression. That helps a lot. Mike Mahoney says his wine cellar is the perfect environment for bowl drying.

Drying is another art form.

robo hippy

 

[Jerry Bailey]

I too have been experimenting with the 24 hour DNA bath, but only with my extremely spalted/punky woods
it produces no cracks when finally dried, and seems to have fortified the wood itself a bit so there's less of a tear out on the end grain sides
drying times for me have been reduced to a couple weeks at most, allowing me to finish turn,
then apply my finishes a lot more quickly, getting the pieces to market sooner ........

I have placed 2- 4x8 sheets of plywood on my rafters in the garage/shop
put all my pieces up there for drying, can't think about putting them outside, as summertime here it gets anywhere from 100 to 125 degrees during the days
( hit a high of 128 last year), that would definitely spoil and ruin my woods
"shop" stays environmentally controlled, constant 75 degrees and 18% moisture (so I can work same either winter or summer)
besides, I have 100's of lineal feet of regular lumber (exotics) that I don't need twisting/warping/cracking, would be a huge waste of $$$$