moisture

[Dave Fritz]

When do you no longer treat wood with anchor seal? I have wood at 8 % up to 18%.

Curious also when wood is considered dry and not green.

Thanks,

Dave F.

 

[Bill Boehme]

When do you no longer treat wood with anchor seal?....

When there is no longer a chance that the wood will crack from losing moisture. If you are sure that the wood is dry all the way through and not just on the surface then there is no need for Anchorseal since its purpose is to slow down the rate of moisture loss.

 

[MichaelMouse]

No absolutes. Wood gains and loses in step with its environment. Eighteen is as low as you get if it's a standard day at 85% relative humidity. If the humidity were 50%, it's 9 points high. I suppose green is anywhere above the fiber saturation point of ~30% (of dry weight) moisture, curing is anywhere from there to equilibrium, and cured is equilibrium.

Makes a difference what shape the wood in. If it's a block, you treat it differently than if it's a roughed piece. A simple round (short piece of trunk) is vulnerable to end checks opening and radial checking from outside to the heart. A short piece with no juvenile wood is still vulnerable to end checks.

It's the difference between where the wood could be and where it is that causes end grain, where loss is ten times faster than face grain, to check as the surface loses faster than the interior can replace it. Bit of a race from >30% moisture to <18% between mildew growth and checking, just to add another variable.

My experience - if you have a differential of <15% between possible and actual moisture content, leave the short pieces of wood bare or just quick seal the end grain. Bigger the difference, heavier the coat. For people without meters, keep the blank at 80-85% for two-three weeks if you can, or seal. If you go heavy when wet, you may have black mildew that spoils as much length (along grain) as checks. More important to have no extreme heat or great circulation than to seal tight. It's slowing loss to allow the interior to keep the end expanded that you're after. Doesn't have to be anchorseal. Can be dilute glue, starch, PEG, anything that slows passage or keeps checks from forming by bulking or preventing separation as the end grain loses.

Great resource to help you make the call at http://www.fpl.fs.fed.us/products/publications/several_pubs.php?grouping_id=100&header_id=p Chapters 3 and 4.

 

[dbonertz]

MM,

Is there a chart that you are using when you say 18% at 85% humidity. Or is there a formula you are using. Doesn't the temperature of the day play a role? Such as 85% humidity on a 40 degree day would be different than a 80 degree before one would say 18% in a bowl blank. I am not challenging you I just think it would be cool if there were a formula/chart one could use for their own shop condition.

Dale

 

[KellyDunn]

Dale, with you being in Ft. Collins you would have the problem of things drying to fast. But unless the moisture in the wood is frozen 40 or 80 degrees is not going to change how much moisture is there.
There probably is a chart geared towards folks who run big kilns and people who just want to know.
I agree that a block is different than a roughed blank for figuring moisture content. 6 to 12% is considered dry by most. 18% could be had from a 6% piece when it gets really wet outside. It does here in Hawaii anyway. Since I kiln dry most blanks even if only 18% I still wax the outside. You could air dry where as I can not. My average humidity is over 80%. Its 86% right now. Bowls that had been dried down to 6% at least got the bound cellular moisture out. But would be north of 16% on the shelf. If I pulled one and finished it, it would go wonky on me. I put the pieces back in the kiln at least overnight to draw that moisture down. As has been mentioned its dry when little chance of it splitting is left from drastic moisture loss all at once. The heat from tools and sanding.
We tend to get heavy dew and moisture at night. I have solid koa doors on my cabinets. They are one shape in the morning and another as the day dries out. Here you have to take to heart the #1 rule that wood moves. I live on the cusp of the rain forest. But we also have desert here. Some of the best galleries are on the dry side of the island. Your normal climate is what the dry side is. That bowl I said would go wonky would stay wonky if I sent it to you or it went to a dry side gallery. Here in my house it would round back out. So I finish them very dry as very few stay here. They go wonky in the house but round out in a dry climate. I have friends in Colo. Spgs who own my work. Seeing how bad they moved made me change how I work. I know. None of this has to do with you wanting a chart. But it does address part of the general thread question.

 

[MichaelMouse]

MM,

Is there a chart that you are using when you say 18% at 85% humidity. Or is there a formula you are using. Doesn't the temperature of the day play a role? Such as 85% humidity on a 40 degree day would be different than a 80 degree before one would say 18% in a bowl blank. I am not challenging you I just think it would be cool if there were a formula/chart one could use for their own shop condition.

It's relative humidity that counts, which means temperature is not a big player. http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_04.pdf Fig 4-1 or table 4-2 cover things pretty well.

Looks like I referenced the location in the prior post, you just didn't check it. Well worth the effort to look at Ch 3 and 4, really. Answers a lot.

 

[dbonertz]

MM, Your right I did not check that this morning. Still drinking the coffee and checking in early then off to get ready for work. I clicked your link and I have seen and read that before but but it has been a couple of years so it became lost in the memory bank somewhere. In my defense running a business, raising kids, volunteering for the club and etc. keeps me plenty busy where some of the less important things get lost on occasion.

Kelly,

Your right about what you say on blanks drying to fast in my climate. When I air dry I have to put anchorseal on the entire blank or lose it. Don't need to worry about mold much like some parts of the country. The kiln where I dry most blanks holds somewhere in the neighborhood of 150 bowl blanks so I understand and enjoy talking with you about kilns since you have a very good understanding about them.
It amazes me actually that I can put a log in the field for a few years and cut 4 to 6 inches off the end and be down to good usable wood. I read all the time how people have to rush to process their logs or lose them do to bugs and rot. I am really spoiled with not having to worry about bugs and rot here. Drying wood really fascinates me not only from my climate but also what people do around the country and really the world to be successful. One of those topics that I hope to gain a complete understanding but am afraid that it will allude me. On the surface it seems so simple but there is more to it than meets the eye.

Thanks for the responses,

Dale

 

[Mjonesrdg]

Equilibrium

When do you no longer treat wood with anchor seal? I have wood at 8 % up to 18%.

Curious also when wood is considered dry and not green.

Thanks,

Dave F.

Dave, EQUILIBRIUM with local atmospheric condition is more important for the turner than what the actual numbers read on your moisture meter. To find equilibrium in your area, use your moisture meter around your home...check your kitchen cabinets, door jambs, desk, etc., and although you will find differing numbers, this will be attributed to the different species you are checking, and most moisture meters come with a chart of conversions for various species. Then, know this: a couple of degrees above or below your "target" MC will not affect the performance of the wood in resisting movement appreciably. Further, know, that a well sealed piece of wood gains and loses at an infinitesimally slow rate.

 

[MichaelMouse]

OR, save yourself the fuss and leave the nail holes out of the woodwork. Buy a hygrometer (humidity gauge) and use that.

They make some fancy ones that mount in turnings, too!

 

[Doyle McEntyre]

Moisture Content

Let me add my two cents about moisture in my bowl turnings. I do about 50/50 solid to segmented bowls. I generally don't like the warped look on solid bowl and use the 10% thickness method for rough turning drying. I anchorseal the whole bowl (have used paint, works OK, little more loss), but I don't use a moisture meter. Being an old retired chemist, I have taken a million conductivity readings and know you are reading the material between the probes. I use a gravimetric method, I weigh the wood. Just buy a cheap balance and weigh the bowl every month until the weight is constant (I air dry). I like to mill my own wood and this the method I use for drying it also. After milling the wood and sealing the ends I stack it with slats and spacing, I mill a section of wood about 50% thicker than the rest and a length that is easy to weight as my test for the whole batch. Wood is always going to move to some extent, dry it, turn it and give it the best seal you can (inside and out) and let nature judge your work.

 

[Odie]

When do you no longer treat wood with anchor seal? I have wood at 8 % up to 18%.

Curious also when wood is considered dry and not green.

Thanks,

Dave F.

Dave.......

Those bowl blocks registering 8 percent MC, are likely KD (kiln dried). Anything 10 percent (and below) MC, and you can forgo the seasoning process.

Different woods and different pieces of the same wood will behave differently........so, there is no one set rule that can be relied upon in all cases. The speed at which wood dries is dependent on many things......like the thickness of the wood, heat, humidity, etc. Bottom line: You can't expect absolute perfection, and should be willing to accept some amount of loss.......average loss is probably around 2-4 percent.

In the past, and as a general rule of thumb, I rough out, and completely anchorseal anything above 12 percent MC. Occasionally, I rough and season with less MC for very special, unique, and/or expensive pieces of wood......just to be on the safe side.

It is best to use a moisture meter to determine the MC at time of roughing. As Doyle says, in the post above this one, moisture meters aren't absolutely necessary, but they are very handy to give an initial idea of just how much MC any bowl block, or roughed bowl has. Moisture meters can also help you to control the dreaded mildew on your roughed bowls. Mildew can be a problem with any wood above 18 percent.

Also, as Doyle says, the best way to stabilize the MC, is to use monthly weighings. My rule of thumb, is to consider the roughed bowl ready for final finishing after three consecutive months of no weight loss. I have many more bowls than I can possibly turn in the near future, so I am allowing more months of no weight gain to pass lately......but, three months without weight loss is the general rule, here.

There may be months of no weight loss, or even a slight gain on rare occasions......but, the general trend will be to lose weight until the MC stabilizes. Seasons of the year, your location and climate, will also effect the rate of weight loss.

Roughed bowls with initial high MC (26-38 percent), will generally loose weight faster in the beginning of the seasoning process, then less, and less. Roughed bowls with lower MC(12-24 percent) will mean they have already lost some MC prior to your possession of it.

You already have a moisture meter......that's good! Postal scales are very cheap and have good repeatable accuracy........get one!

ooc

Edit note: I roughed a Claro Walnut bowl block in the past week that had an initial metered MC of 10 percent. After roughing and rechecking with the moisture meter, the roughed bowl now registered a reading of 18 percent MC. This indicates that a turner cannot rely on the moisture meter as an absolute. It's a useful tool, but not conclusive as to the MC in the interior of any given piece of wood. The thicker the wood block, the more likely the surface of the wood is NOT the same as the interior. Many bowl blocks are 2" thick......these are more reliable for accurate readings.