DNA drying method failure

[Rob Holcomb]

I was hoping to speed up the drying process on roughed out bowls and read many posts offering different methods of drying bowls. I decided to try the DNA method and followed the instructions exactly as has been described on here and other web pages. I did two bowls. The first was my very first rough out using Cherry wood and the second was a much better roughing out using white oak. Both bowls cracked quite a bit. They both became firewood. I know most use anchorseal and that will be what I try next. I know some people swear by the DNA method but I am curious if others found that method to not work very well like I did?

[Aaron Wingert]

DNA certainly isn't a cure-all, but it greatly increases your chances of success. How the soaked blank is roughed-out, how long it soaked and stored after soaking has a heck of a lot to do with how successful the end product will be. I find the method to be successful most of the time, but certainly not on every piece of wood.

If you go into detail and describe what you did and how you did it we might be able to identify where you might've gone wrong.

Anchorseal is almost a staple in drying of blanks but has the most value in slowing/preventing initial moisture loss through the end grain after cutting, and instead forces the moisture to escape through the cell walls....Very slowly.

[Brian Effinger]

If you go into detail and describe what you did and how you did it we might be able to identify where you might've gone wrong.

+1 for that. ^^^

I usually fully immerse my turnings in the DNA for at least 24 hours, sometimes more. Then I let it drip dry for a few minutes. After that I wrap the outside of the bowl with brown paper bag paper, and let it roll up over the rim. I secure with some rubber bands, and then weigh it and record that number on the bag. I'll then set the bowl on something upside down near the floor. I figure that air will still be able to circulate underneath, but not too much. I'll weigh it every few days and when things start to slow down, I'll sometimes move the bowl to another location, still upside down, but higher off of the floor. I should also mention that this goes on in my basement.

Also, some woods, like oak are more prone to cracking, so the process has to be slowed even further. I've worked on some pin oak, and for that I initially set the wrapped bowl on top of the wood shavings pile for a few days, before moving it to another location near the basement floor.

I hope that helps.

[Jeff Nicol]

I just can't see the need for having something that is very flammable in a tub, bucket, bag or whatever to try and speed up drying a bowl. I most likely will never try it for just that reason. I think you picked 2 of the worst woods for cracking to start your process. All of the fruit woods are prone to cracking quite a bit. The oaks are fast drying woods as they have larger pores and let the water evaporate much quicker than most other woods. With that being said, I use anchorseal or parrafin if I am out of anchorseal. But like already said the thickness you leave the roughed out blank and the process after you rough it out have a lot to do with how it will dry. I think with the DNA method you could/should turn the bowls thinner than when you are going to seal them and set them on the shelf for 6 months to a year. If I am in a hurry to get a piece done, I work on it a little bit every day, either putting it in the sun for a few minutes, or by turning away a little bit every few days, keeping them in a grocery bag, paper or plastic at night then take them out while I am in the shop so I can keep an eye on what the bowl is doing. I can get a bowl finished in a couple weeks this way with very little warping or cracking, it jus takes time and perserverence.

Good luck,

Jeff

[Scott Hackler]

I use the dna method exclusively and have almost 100% sucess with it. Some woods really warp (ie oak and hackberry) but hardly ever crack. The only species that have cracked were ornamental plum and apple. Both are extremely hard to keep that from happening.

Most times I rough to 10%, soak for min of 24-72 hours and wrap with 2-3 layers of newspaper (taped shut) poke a few holes in the open part of the new package, write on the tape whats in it and when I wrapped it, sit of shelf upside down for 6-8 weeks, unwrap and finish.

Works for me a lot better than just anchorsealing (which work well) becuase it takes 1/2 the time or less using Dna. Just wrapping with no Dna didnt work well at all for me. That caused a lot of cracking.

[Ralph Lindberg]

Ron

You have hit why the Forest Products industry does not use DNA, it's not remotely predictable. For them, they need 100% predictable and cost effective (the other reason they don't use chemical drying)

The only "industry" I am aware of that uses chemical drying is Archeology, and they have years to burn (see Mary Rose as an example)

Me, I want something that is predictable and reliable. Slow drying and boiling appear to me to be the only two methods that are both

[Scott Hackler]

Yeah but Ralph, the industry doesnt "slow dry" they use a kiln, which is a ton faster than anchor seal or just wrapping it up and waiting. If I had a kiln I would definitely use it and fore go the Dna method, as I am impatient and dont want to wait a year for my rough outs to dry. Each person will use the method that serves thier own purpose and timeline. For me the Dna method works GREAT and its fast. I have dried approximately 30-40 projects using it and have about 98% positive results. These projects range from super small (green pen blanks) to 2 monster maple bowls (15" diameter roughed).

:)

[Bernie Weishapl]

Rob I to have had excellent luck with DNA. I like Scott have had 99% positive results. I soak fruit wood such as cherry, apple, crab apple, etc for at least 5 days, then wrap in brown grocery sack. Oak is a bad wood and does a lot of cracking anyway but have had pretty good luck with it. Most woods I soak 3 to 5 days, flash dry and then wrap. I cut a opening in bowl portion up to the rim. I have around 34 or 35 dry now with no cracks in any of them and 12 are cherry. I also store them on or near the floor in a cool room that stays around 40% or maybe a little higher in humidity.

[Reed Gray]

While I turn to final thickness, and let them warp, one general rule for drying bowls is that if it cracks, you are going too fast, and if it molds, you are going too slow.

The one thing I picked up from the DNA soakers is to wrap the outside of the bowl, and leave the inside open. The idea is that the inside dries at a faster rate, and as it shrinks, it 'pulls' the outside inwards. I did try totally enclosed in the paper bags, and it didn't work too well. I did the newspaper with tape, and the open center, and it worked a lot better. I tried the paper on the outside, and secured to the rim with 6 inch stretch film a couple of times around the rim, and that seemed to be the best trick. I now, just wrap the rim with the stretch film, about an inch on the inside, and the rest on the outside. The idea is compression of the rim. I do start them out on the floor for a few days, then up on a shelf. Dry in 10 to 14 days. On the thin bowls, the DNA and LDD (liquid dishwashing detergent) soaks make no difference in drying, but the LDD makes it easier to sand out. I

Do make sure to round over the rims before you take the bowl off the lathe. A sharp square rim is much more prone to splitting. It also can slice your hand up if you use it as a steady rest, which I do.

robo hippy

[Bernie Weishapl]

Reed is right and I forgot to bring that up. Rounding over the rims will definitely slow down or eliminate the cracking on the rims. Reed and Mike put me onto this and haven't lost a bowl since.

[Rob Holcomb]

My procedure was to rough out to 10% and I did round over the edge of both bowls. Then I soaked the bowls in DNA for more than 24 hours but less than 36 hours. The exact time, I don't know. Then I let them drip dry for about 45min to an hour and then completely wrapped them in 3 layers of newspaper. I secured the paper with masking tape and then cut out the top to expose the inside of the bowl. This caused the newspaper to need more tape around the top edge to keep the newspaper in place, which I did, all the way around it. Then I placed the bowls upside down to dry inside my house on a shelf I have in a storage area that has no door so air can move around in there. The shelf is one of those wire mesh shelves. I don't know what the humidity level was in the storage area but I would guess around 50% on average. I weighed the bowls every couple of days and when they were losing no more than 1/100th of an ounce daily, I took the newspaper off and saw the cracks. Both were about 1/8th inch wide and an inch long. I'm willing to give this method another try if there are things i did wrong or things that you think need tweaking. Currently I have on hand..logs of Cherry, White Oak, Ash and Rock Maple. Because Cherry and Oak tend to crack more than other types of wood, maybe try Ash or Maple?

[Steve Schlumpf]

Rob - I have been using the DNA method for a few years now with pretty good results - but I do get cracks ever once in a while. Any chance we can see a photo of one of the cracked bowls?

In addition to what everyone else mentioned - I found that the tenon area was very susceptible to cracks if the inside of the bowl was too thick. The 10% rule works well but I found that my cracking problems almost went away when I made sure the bottom of the form was slightly thinner than the walls. Also, make sure your tenon isn't over-sized as that adds to the bulk.

Judging from your description of your procedure - you did everything right. There could have been hairline cracks in the cherry even before you started drying it - you just never know.

[Rob Holcomb]

Hi Steve, Unfortunately I don't have any pictures of the bowls. They became firewood after I saw the cracks. I didn't see any problems with the tenons. The cracks were on the top of the bowls. I'm going to give this another try and see what happens using Ash and Maple.

[Reed Gray]

Rob,
Were the cracks off the rim, or in the middle or bottom of the bowl? If you leave the center/pith of the log in the bowl, you can guarantee a crack. If you don't turn out ALL of the cracks before you start to dry, they will get bigger. Any knot will generally spawn cracks. Try the stretch plastic film on the rim, it doesn't take much compression to prevent cracking.

robo hippy

[tom martin]

I agree with Jeff on having a large open container of dna in the shop.I heat with wood and don't need a shop full of solvent in the air. Besides I really don't like the smell. I did try it a year or so ago with fairly good results, but I'm in the "keep on roughing til the first ones dry" camp. I anchor seal the whole bowl and "Set it and forget it".
I have also tried a product called "Cedarcide" which is food safe dries wood faster than DNA and stabilizes punky wood -to a degree. The down side is that it's $50.00 a gallon when purchased in a 5 gallon pail! I only use it on special pieces. The rest get anchor seal which is only $27 for 5 gallons when my turning club buys a 55 gallon drums.

[tom martin]

One thing I forgot to mention in my previous post. I saw a video on utube that showed a production bowl shop in Michigan (I think)and they steamed their bowls after coring. I don't have a steamer, but I do have a canning pot on the stove that will boil water (during the winter).
I had made a set of bowls out of a beautiful birch burl from and for a good neighbor and the second largest bowl developed a 1/4 inch wide crack from near the rim all the way to the bottom. I was upset and thew it into the canning pot and left it there for a day. I pulled it out and the crack had sealed shut! I CA'd the crack and bagged it and set it on the floor to dry. Hopefully it will stay shut.
I have seen other videos that promoted boiling as a drying method. They used a turkey fryer and a 55 gallon drum. The claim is that it speeds up drying and equalizes internal stresses to eliminate cracks.
Good luck
Tom

[Roger Wilson]

... If I had a kiln I would definitely use it and fore go the Dna method...:)


Well build one then. It's not difficult, not expensive, and bowls take no more then three weeks to dry. See link for articles on building kilns:


http://www.woodturningonline.com/Turning/Turning_articles.html#drying