Wet Turn and Sand - Now with Pics!

[Rich Aldrich]

I turned a bowl and sanded it wet. It is in a paper bag drying. Is there anything else I should do to it? It wasnt flinging water, but it was burl off a slab of a log cut sometime last winter. We just sawed it into lumber yesterday.

Normally I soak wet bowls in DNA, dry in a paper bag, finish turn, sand and finish.

I will take pictures tomorrow and post.

[Dennis Nagle]

Why do you and others soak bowls in DNA??? how long do you soak them for?

[Dan Forman]

I've never done a bowl this way, but when I turn a hollow form to finish green, I let it soak up as much finish as it will, either oil or wiping varnish, then bag it loosely for a few days. That's all that seems necessary for hollow forms.

Denis --- the DNA bath (usually overnight) allows the denatured alcohol to replace the water in the green wood, which then will evaporate much more quickly, allowing it to be finished turned in a few weeks to a month or so if I recall. I did this for a while, but wasn't that taken by the process, still got some cracks, and went back to bagging and waiting, or anchor sealing during dry times or for difficult wood.

Dan

[Dennis Nagle]

Thanks Dan. I agree. Everytime I try to speed up the drying process I see cracks no matter how I do it. I have not dried the microwave yet.

[Reed Gray]

Well, I always wrap the rim with stretch plastic film, and make sure to round over the rims. I turn to final thickness, about 1/4 to 1/2 inch max. I do let them dry before sanding, mostly because it takes more time to sand green bowls than it does to sand dry ones. The problem is with warped bowls on a lathe. You need speeds of about 20 rpm to be able to keep any abrasive on the wood, and the phase converters can be programmed to go that slow, but the big name companies don't want to do it because they fear over heating. I have done it for over 10 years, and the lathe runs cooler at sanding speeds than it does when I am turning. I tried bagging, and got mixed results. With the plastic shrink wrap, success was much higher. I do start them out on the concrete floor where it is cooler and has higher humidity. Concrete, unless there is a vapor barrier under it, will always have water in it. They are dry and done warping in 7 to 10 days, and if you are in a hurry, they can be sanded in 3 to 5 days. The DNA soaking does nothing for thin turned bowls. Nothing is in crack control, stabilizing, or drying quicker. I do LDD (liquid dishwashing detergent, cheap brown Costco, mixed 50/50 with water, 24 or so hour soak, rinse, and dry as normal) soak because it makes woods much easier to sand out.

robo hippy

[Rich Aldrich]

This is the bowl. It is about 3/8" thick. I didnt have the courage to go thinner. I had sanded through 600 grit before I posted last night. Some of the sanding dust is in the bark and has to be cleaned out when it drys enough.

My wife thinks I am nuts. Who would want a bowl with holes and bark? It is supposed to be a form of art.

[Rich Aldrich]

Thank you for the input. I agree about the DNA soak for finished bowls. Besides, the DNA is so dark, you would have to cut the surface wood off to get back to true color. I did sand it wet and it did take longer. I have found that burl wood sands out very well compared to regular wood probably because the density is more uniform. I would think that fiber distribution and size is more favorable with burl wood - you dont have the end grain issues.

As far as DNA soak, I have had very good luck. I probably turn 50% cherry and have talked to experience turners that have problems with cherry cracking. The only issues I have with cherry cracking is where there are defects such as knots. Sometimes you dont know the knots are there until you start to turn.

Reed - I like your method of sanding at the slower speeds. The VFDs at work we are able to program either with a laptop or a screen. I am interested in getting into the programming of the drive and messing around with the low speed. I might try another vendors drive on my lathe at some point. They are in the range of $175 for a 2 hp the last time I checked.

[Reed Gray]

Rich,
Which lathe do you have? The old PM3520A models would go down to that 20 rpm range, then they changed it to 50 rpm for shut off and start up speed, and owners are locked out of the converter. When I asked why, they told me it was because the motor would over heat, and you would fry the electronics. When I told them I had sanded out thousands of bowls at those low speed ranges with no problems, I was told that it was impossible, and their 'lab' tests showed the motor over heating. I told them I had used the 'hand test' to see how warm the motor was and found it not hot at all, they still insisted it was impossible. If I wanted one reprogrammed, I had to send the unit to them, they would fix it, and then they would void the motor warranty. I have had my Robust reprogrammed so it will go that slow for sanding, and it runs cooler than when I am turning. I also had it reprogrammed to run at higher speeds because the low range was just too slow for me, and the mid range was also a bit slower than I liked. There is a lot that can be done with the converters, and I can see why they might not want a person like me messing with it because I only know what I want it to do, and not how to do it. Being an electrical engineer would help you figure out what the hand book for the converters is talking about. There was a long thread over on the AAW site in the Tips and Techniques section about the code for getting into the converter for Jet/PM lathes.

For drying finish turned green wood bowls, after a lot of experimenting, I liked the DNA soakers idea of wrapping just the outside of the bowl, covering the rim, and leaving the inside open. Theory was that the inside would dry at a slightly quicker pace, and kind of 'pull' the outside inwards, in a compression mode. When I tried that part on my bowls, success rate went way up with my Madrone bowls, which warp insanely, and crack when you pull the chainsaw out of the truck. I tried the tape method, and it worked, but was a bit of a bother. I then used the stretch wrap, and it secured the paper pretty well. I then wrapped just the rim, and the success rate was unchanged. Now, I just wrap the rim. The DNA soaked bowls (I did several hundred dried in DNA) did seem to be 'harder' to sand out than non soaked bowls, and the LDD soaked ones were far easier to sand out.

I did read about another turner on another forum (can't remember which one) who took to sinking his bowls in a clear water stream behind his shop for 2 weeks. Cured his drying problems. Interesting, but I don't have a stream to experiment with. The water soaking method has been around for a while, and rain barrels and horse troughs, and even ponds have been used. Problem with them is discoloring of the wood as in slime, mold, mineral stains, etc. A clear stream would keep the water fresh and clean. Maybe it is a slow way to accomplish what boiling or steaming does.

robo hippy

[Rich Aldrich]

Reed,

I have the Jet 1642 so I will check out the thread on AAW. That could prove to be interesting. I am a mechanical engineer but with my job that I just started 9 months ago, I have to know a lot more about electrical engineering.

I will have to get some stretch wrap and try your method. I noticed the same thing that bowls soaked in DNA tend to sand harder than bowls not soaked in DNA. This could save some sanding time and reduce sandpaper usage. I havent tried wrapping the outside of the bowl yet, but now it is on my trial list.

We actually steam beech at work. It gives it a red color similar to red oak. It really improved sales. We have a beech disease that is killing most of the beech in the Upper Peninsula. There is a lot available so the steaming process helps the whole cause.

I had not heard of the water soaking method. That will be something to try.

I also thought about bringing a couple of roughed blanks into work and having our kiln operators kiln dry them. I am going to talk to our head kiln operator and see if he would be willing to let me put a few blanks in to see what will happen. The stretch wrap might really help in this process as well since it protects and supports the rim.

[Donny Lawson]

Why do you and others soak bowls in DNA??? how long do you soak them for?

Soaking bowls in DNA for between 24-36 hrs ( I have left them in the DNA for a week) just make them dry out faster and can be finished faster and sold faster so you can make more faster. After taking them out of DNA let them air dry for a few hours then wrap them in newspaper and they should be ready to finish in a few weeks instead of a few months.

[Steve Kubien]

Hey Reed, I just thought I would chime in that my Stubby goes low enough in rpm's that you need a calendar to track them. I've started doing a few bowls the way you do and so far, I've been pleased with the results.

[Reed Gray]

I have never turned on a Stubby. They look pretty alien to me, but those that have them love them. Yes, the low speeds are necessary for sanding warped bowls.

robo hippy

[Brian Finney]

Well, I always wrap the rim with stretch plastic film, and make sure to round over the rims. I turn to final thickness, about 1/4 to 1/2 inch max.
robo hippy

Reed,

Do you mean that you cover the top of the bowl ie there is no drying from inside of the bowl, except thro the wood ?
Or are you just covering the rim.

Brian