DNA test

[Gordon Achterhof]

As a beginner, I don't have 6 months of wet turnings just waiting to be finished. So,,,,, I figured that the next best thing would be to test the DNA soak bit. I roughed out four bowls from wet oak and took one of them and put it in a brown bag along with some wet shavings. The other three were drowned in DNA for about four hours and then drained and the outside was covered with either a bag or the local newspaper and sealed around the rim. The results of all this is the bag and shavings didn't make it three weeks until it split from rim to bottom. The other three were weighed every day until they quit loosing weight. Or rather two of them did. The third is still on a weight reduction program. Finish turned the two that are dry and as you can see from the pictures, no cracks. Looks like the DNA wins hands down.

[Jim Dunn]

Thanks for the test Gordon. Some of the stuff I've drowned split and some of it didn't. But then again I'm not one to wait very long for em to dry. Usually 1 week or less

[John Hart]

Yup...the DNA seems to work pretty well Gordon...as you have so aptly shown. Doing nothing has always been a loser for me. Nice bowls by the way!!!

[Chris Barton]

As a beginner, I don't have 6 months of wet turnings just waiting to be finished. So,,,,, I figured that the next best thing would be to test the DNA soak bit. I roughed out four bowls from wet oak and took one of them and put it in a brown bag along with some wet shavings. The other three were drowned in DNA for about four hours and then drained and the outside was covered with either a bag or the local newspaper and sealed around the rim. The results of all this is the bag and shavings didn't make it three weeks until it split from rim to bottom. The other three were weighed every day until they quit loosing weight. Or rather two of them did. The third is still on a weight reduction program. Finish turned the two that are dry and as you can see from the pictures, no cracks. Looks like the DNA wins hands down.

Gordon,

This is a great post! First, the bowls look great! Second, I love science and a scientific approach to learning and you did a great job of that. But, there is a question that remains unanswered. So, the assumption with DNA is that you are displacing water in the wood but, what actually happens is that the water in the wood moves into the DNA. So, if you were to measure the specific gravity of the DNA with a float hygrometer what you would see is that the DNA becomes more dilute with each and every use.

Thus, the questions is; when do you know it's time to change out your DNA? One way would be to check with a float hygrometer. But, it would be interesting to hear what folks actually do.

Again, great post!

[Bernie Weishapl]

Great looking bowls Gordon. Thanks for the info. DNA seems to work well for me also.

[Cody Colston]

Great post Gordon and very nice bowls, too.

Do you find that Oak moves a lot? Even the DNA soaked Oak bowls I've done warped so much that the 1" thickness per 10" diameter rule-of-thumb was barely enough to finish turn them.

Chris, I keep my DNA in a 5-gallon plastic bucket with a lid. Due to evaporation, I occassionally have to add a gallon to keep it at the full level. I figure that accounts for the absorption of water from the bowls.

I know, that's not very scientific.

[Lee DeRaud]

My question is, how long does a batch of DNA last?

Alcohol (especially ethanol) is aggressively hygroscopic. Unless there's some mechanism in play here that I'm completely unclear on, it's mostly acting as a dessicant on the wood and, like any dessicant, it will become saturated with water. But unlike most dessicants, there's no way (except maybe distillation ) to remove the water from it so it can be reused.

(Edit: oops, just saw Chris' post with essentially the same question...so it goes.)

[Chris Barton]

My question is, how long does a batch of DNA last?

Alcohol (especially ethanol) is aggressively hygroscopic. Unless there's some mechanism in play here that I'm completely unclear on, it's mostly acting as a dessicant on the wood and, like any dessicant, it will become saturated with water. But unlike most dessicants, there's no way (except maybe distillation ) to remove the water from it so it can be reused.

(Edit: oops, just saw Chris' post with essentially the same question...so it goes.)

Exactly what Lee says! ETOH will suck water out of the air and will seek to become as dilute as water. Theoretically, you could weigh the bowl before and after soaking and get an idea of just how much water is in the alcohol. Water weight 1 g/cc. I would be willing to bet that most of the alcohol baths used by folks like us after 30 days are less than 50% alcohol.

[Andy Hoyt]

The rule of thumb I've heard (and I think it came from Dave Smith) is that we'll lose more volume from our container by the ETOH soaking into the wood than water getting passed into the container. So as the container runs low, just add more ETOH and the concentration is restored. Dunno if it works, but it seems logical.

[Frank Stevens]

But unlike most dessicants, there's no way (except maybe distillation ) to remove the water from it so it can be reused.

Not neccesarily. While doing a little research on distillation (you can get a permit to produce your own E-85)
I found that there are some crystals or perlite like pieces..(started with a z I think) that you can add to your alcohol and they will suck the water out of the alcohol. You can dry them in a pan on low in your BBQ and reuse them if your careful.

Frank

[Jim Ketron]

Guys all I can say it works!
I have a large container thanks to Big Mike and a 5 gal bucket I have used for about 1 1/2 years.
sure a small amount of water gets in the mix but most of the unbound water is slung off during the turning of the piece leaving the bound water and this is what you are trying to remove to dry it. The blanks that you put in there soaks up the DNA thus you loose some of the DNA with each turning so you need to replenish after so many bowls, so your always adding DNA to the batch.

So how long is long enough?
After 1 1/2 years of using the same bucket, and I have turned and soaked many bowls and hollow forms they still dry in about 2-3 weeks!
So IMO the amount of water that gets in is not very much!
Jim