drying oak - avoiding cracking

[alex grams]

This is a side bar/follow up to a previous thread on my attempts to alcohol dry some red oak blanks.

From all I have read, it seems to be one of the more crack-prone woods.

I have tried turning to 1/2" thickness and alcohol soaking,but still am getting cracks. My next thought is to turn to final thickness and alcohol soak, then do some spot treatment of anchorseal on the end grain of the bowl.

Does anyone have some direct experience or input to drying the wood to help avoid cracking?

Thanks in advance.

-Alex

[Reed Gray]

Red oak is prone to splitting. On drying, one rule of thumb is that if you dry it too fast, it will crack, and if you dry it too slow, it may rot and/or spault, which is not always a bad thing. Thing is there is a huge amount of variation on how to do this depending on the wood, and local humidity/weather. I would not suggest the anchor seal, unless you plan to turn it off. I don't know of any other way to remove it. With the soaking, you need to first make sure you round over the rims. The sharp edge will not only cut you, it tends to promote cracking where the rounded rim helps stop it. Also with the soaking, it is important to wrap the rim. Most of the DNA soakers will wrap the outside of the bowl with newspaper, and tape it to the rim, leaving the inside open. I do it different by wrapping the rim with some of the stretch plastic film (5 inch wide rolls from office supply). About an inch inside/over the rim, and the rest on the outside. This can be done with the news paper as well, but I haven't used the paper for a while. Important part here is to stretch the film out and go around a couple of times, at least twice. This puts the rim under some compression which helps prevent splitting. Next, when drying, you want the area free of drafts, heat, and direct sun light. I start out on the floor of my shop (higher humidity and slightly cooler temps). Down there for a few days, then up on a wire rack to finish. A 1/2 inch bowl is dry in about 10 to 14 days. Thing here is are you planning on twice turning (turn, dry, return) or turn to finish thickness (turn, dry and warp, sand and finish). With 1/2 inch thickness, you may be able to return a 6 inch bowl with that wall thickness, but not much beyond that.

The art of drying means learning what works best from where you are, and how to deal with the different woods. Just because it works once, doesn't mean it will work again, or maybe it will work a few times, but not others. Every wood is different, and each piece can be different, even from the same tree.

robo hippy

[Prashun Patel]

If you think oak is bad, try beech. When in doubt, it's wax (sometimes two waxings) and bag for me. After roughing, I wax the whole thing, let it dry for a day, then put it in a double brown bag or put it in a waste bin full of shavings. Take it out every couple days to check and to watch for mold. If it molds, I leave it out for a day or two, and then back in the bag. After a couple weeks, it can come out of the bag for good.

It is a balance, but given the choice between black or crack, I choose black. it usually turns right off.

[charlie knighton]

oak: the day the tree is cut down, cut in blanks, no achorseal or anything, put in cardboard barrels (55 gal), seal, let set for at least 4 months, some blanks will crack, 90% will be good to go, the rust problem with tools and lathe bed is gone also

for 4 months large blanks inside will be moist and may warp, unless hollow form, the shape will prevent warpage mostly

2 years probably no warpage

[Dennis Ford]

I have had good results with oak when turned to finished thickness while wet. I have had OK results with oak turned to 10% while wet and then coated completely with Anchor-seal. The Anchor-seal slows (does not stop) drying. My climate is more humid than yours, you may need a heavier coat (or two coats) of Anchor-seal. Turning to more than 10% increases the chances of cracks and less than 10% will likely result in a warped bowl that can not be made round.

[Bernie Weishapl]

I also anchorseall all my bowls and turn to 10%. Another thing I have found is to round over the rims. A square rim has more of tendancy to crack IMHO. I also store mine on the floor in a cool place with little to no air flow. I have also had ok luck with oak.

[Dave Bunge]

I had a terrible time with oak in the past. I tried anchorseal and/or bagging, one bag or two. Usually I would get cracks or mold, often both on the same bowl.

Then I got some humidity meters and started snooping around. My basement shop, where I had tried drying with no luck, is about 60F and 30% RH this time of year, warm enough for mold to grow, dry enough to encourage cracking. My garage is 20 - 35F and 55 - 80% RH. Too cold for mold, humid enough that blanks dry slowly. I have several bowls rough turned to 10% thickness drying in my garage now in paper bags. They are halfway to dry with no sign of problems yet. (Fingers crossed.)

[alex grams]

Dennis, when you turned your oak to final thickness, did you just DNA soak and wrap then let dry? Or what was your method for drying when you turned to final thickness?

[Dennis Ford]

Alex: I am too frugal for DNA soaking. For final thickness turnings, I wrap them in in brown paper for a few days until they dry out. Then I take them out and sand / finish.

[Prashun Patel]

I'm going to move my bowl drying rack to the garage. Thanks, Dave.

[mark ravensdale]

Yep beech can be a real pig to dry, it seems to crack/split just because you looked at it the wrong way, I rough turn it then dunk it straight into my gloop ( washing up liquid diluted with abt 20% water and around 2-5% household bleach) for 48 hours, then left to drain for around 1 hour then into brown paper followed by several sheets of newspaper (broadsheet ( tabloid too small)) then left on a shelf for at least 6-8 months, this has proven quite successful for me with only around 10-15 cracking/splitting (which can still be used by making a feature of the crack/split (wood burning or lacing))

Sorry if this is a little off subject but someone mentioned the problems with beech:)