[OP]
Contributor
I have a stickered stack of 4/4 white oak, most are 12" wide and have been in a commercial metal frame building, unheated, for over 2 years. I do not have a moisture meter, and am wondering if I am making a mistake to start without knowing the % moisture. Any advice?
Last edited by Joe Cowan; 12-18-2012 at 11:24 AM.
Member
To start what?
Cut into one and take a looksie. You could weigh a section, and then cook it in the oven for a few hours on low heat while the Mrs. isn't around, and then let it cool and weigh it again to see how much water has left.
If you know what wet wood feels like, you might not have to go through the cook test.
No rocket science here.
Todd
Contributor
I will make a statement, and am curious to hear the reaction:
It doesn't matter what the actual moisture content is
What I mean by this is, that it's possible to be too 'low' in content if the environment in which the finished produce will be is a high moisture environment. Most times though, the storage environment is different than the house where it will finally rest. And some inside environments can vary greatly over th course of the year.
2 years in a storage space sounds good to me. But that assumes this storage space has some protection and control, and also I would worry about the pieces closer to the floor if it's concrete. You could have differences through the stack that could be a lot. Also sometimes it can get really hot in the summer inside some spaces, which would drive moisture out only to go back in during the more humid months. (or if no ventilations, could make the space more humid even)
Consider the air inside the storage space, and consider the air in your house, and go from there......
Contributor
I never use lumber w/o knowing what the moisture content is. Just doesn't make sense to take a chance, and that goes for KD lumber, too. You have 3 options that I can see. Use it and hope that ignorance is bliss. The two better options are to do the oven dry test described above to determine the moisture content or to just measure the humidity inside the storage building. Hang a low cost hygrometer next to the wood and go check it several times over a week. Your wood will have an EMC close to that value that corresponds with the average humidity you observe. Here's a chart of EMC vs. RH: http://en.wikipedia.org/wiki/File:Ha..._EMC_graph.svg Now compare that with the RH and corresponding EMC for your shop. If the EMC is within a couple of percent you could use it after only a few days acclimization. But if your shop is say 40% RH while the storage barn is 75%, then the difference in EMC is around 7 vs 14% and using the wood right away would just lead to problems. At a minimum, you would have to sticker it in your shop for several weeks for the EMC to come down to within a couple of percent of where your shop is.
A serviceable moisture meter really doesn't cost much. To me, it's as important as any of my other tools.
John
Member
I think the basic premise of your paragraph is OK....although it seems to ignore the possibility of the wood being too wet! I guess I just wouldn't have started with this phraseOriginally Posted by Carl Beckett
Now there are many different uses of wood and each will dictate ideal moisture content. For instance, construction lumber is usually higher moisture content, IIRC about 16% +/-....which is actually good. If it gets too dry it's harder to cut and tends to split when your trying to nail it! A lot of turnings benefit from wet wood as well. Most interior work is better in the 6 - 8% range however. While it will still move when put into service, and seasonally after that, that movement range is very generally speaking pretty small. And as long as one uses good design should be OK. If however one tries to build a piece of quality furniture using wood that's say 20% + moisture content.....your looking at impending doomThe amount of shrinkage while that piece continues to dry out over time, depending on the complexity and method of construction, will certainly have a pretty negative affect on the piece.
So while it's probably not going to be a problem if the wood is a little outside the ideal MC range and is understood when designing the piece. If the wood is overly wet that's just not good!
My concern is whether the wood was dried out properly? I'm no expert on this topic, but my understanding is that wood which is going to be air dried should initially be done outdoors with adequate air circulation. Was this wood dried before being taking inside the building? Or has it been there since milling? I think buying from an established lumber supplier can be fairly safe without utilizing a moisture meter....however if I was using air dried I think I'd want some sort of insurance
good luck,
JeffD
Contributor
This is the point. The moisture meter is a means to an end, and the value needs to be compared against the final environment of the finished piece! Too often people just quote a moisture value.... Not the complete picture.
And I do believe 'how' it's dried matters. Looks for checks and cracks and spalling, etc. That usually takes care of itself just by observation.
White oak, I believe, takes longer to dry than other species (I have a stack but haven't cut into it yet.... It's only been a year)
[OP]
Contributor
After thinking about it (worrying) I am going to go back to a stack of kiln dried red oak I have and get started. Will work on a white oak project in another year. Maybe have a moisture meter by then.
Contributor
With regards to building furniture, let me try this in a more direct way. When you work wood it should ideally be at the same moisture as the shop in which you are working. When building you should design/build for the anticipated moisture content range where the furniture will reside.
OK, why did I say it that way? Well, if you bring wood into your shop that has a different moisture content than your shop, moisture will move into it or out of it depending upon whether it's drier or wetter than what your shop is. While it's doing that it will move when you cut it, cup when you resaw it, bend when you rip it, on and on. Sometimes it will straighten out if you wait for it to equilibrate, sometimes not. Worse, if a piece bends when you rip it and then you joint it back straight it will bend again as it dries, and now you are really cooked. The extent to which this happens depends mostly upon how far the MC of the wood is away from the EMC of your shop. If you cut wood that is in perfect harmony with the EMC of your shop it will not cup, bend, etc. when you cut it unless there are internal stresses in the wood. You have no control over those stresses, but you do have control over the MC, so you are wise to minimize problems by making sure the MC is in harmony with your shop.
If you build a piece of furniture with wood having a MC equal to the EMC of your shop you can still run into problems later if you do not build properly for seasonal movement in the location where the furniture will reside. The two classic examples of this are drawers/doors that won't open in the summer, and panels that shrink out of their frames in the winter. These problems must be addressed both in the design and build phase of the project. If you don't know what the MC is of the wood you are using, you are likely to make a mistake in the build phase even if your design was good. Building tight in the summer and loose in the winter is nice to say, but I've seen a lot of old furniture with the problems I just mentioned above. So the builders didn't now about proper design, didn't care, or didn't know what the MC was of the wood they were using. I'm sure all three were the problem depending upon the circumstances. What I know for sure is that moisture meters didn't exist a hundred years ago. Today they do. There are also many good reference books available from which we can all learn about how to design for seasonal wood movement. Together, they cost far less than the cost of wood for one project, and it just makes no sense to me why so many people don't have either. I'm sure someone is going to come back and say they've never had a problem; well, good for you. I knew a farmer when I grew up who could tell how dry hay was just by rubbing it between his fingers. I know of other farmers who's barns burned down because they thought they could tell how dry it was.
John
Even when
Member
White Oak is unique in that it can take much longer to air dry than other woods. Reason is the lignan capillaries (think of wood as a tight bundle of straws) have internally distributed axial seals that function much like watertight bulkheads in a submarine or ship... That's why it is the only source of Oak that can be used in coopering barrels for aging wine, whiskey or brandy. Keeps them water-tight, leak-proof, and acts to limit the "angels share" over extended periods. As mentioned, there are a number of useful empirical tests readily conducted that can reveal moisture content other than investing in an electronic moisture meter.
Member
The rule of thumb is that it takes 1 year per inch of thickness to dry green wood. I would think that 2 years in a protected building would be past that. I recently bought some kiln dried ash that had been stored in an open metal shed and the moisture level had gone back up because of the extended humid days (yes, even in Texas sometimes) and the wood needed to be stickered in my shop for several weeks before using. You might need to take the shop humidity condition into account when starting your work.
Contributor
Depends on what you are going to build as well. Display cabinet with tall doors, I'd say the doors will likely warp in the house this winter. Small table, no problem.
Member
This is a great question/thread. I have similar questions and thoughts...what is the final location of what you are building?
I have a similar issue-that I'm not sure how to resolve. I've got a huge stack of beautiful red oak from a large tree I cut down in my yard. It has been air drying for close to a year. I've been told to bring it int he shop, let it acclimate, and slowly work it. What I'm not clear about is how to keep it relatively straight while it acclimates to my shop.
Contributor
If the wood has been stickered properly and out of the weather it is likely now somewhere below 20% MC. You don't say what relative humidity your shop is, but if it's in your house it could be down below 50% by now. Mine is around 45% right now. You should be able to bring anything 6/4 and less into your shop for final drying; 8/4 or thicker might need to AD longer outside - I'm not sure. When you bring it in you should sticker it again, and you can stack cement blocks on top or band it if you are worried about it twisting, etc. I never have, but it's cheap insurance. To know when the wood has acclimated you can check it with a moisture meter or use the oven dry method. When the center of a board is in equilibrium with your shop, it's ready. I'm guessing it will take several weeks in a heated shop at 50% RH or less. A fan blowing gently through the stack will speed up the process, but better too slowly than too fast, although red oak is pretty tolerant. If it's an unheated garage it'll take a lot longer - like next Spring/Summer.
I have no idea where the comment to "slowly work it" comes from. When the wood is in harmony with your shop it's ready to be worked, fast or slow. If it cups, bends, etc. the moisture content is not uniform from outside to the center and it's not ready.
John
Member
By "work it slowly" I think he meant that when I began to surface the rough material, to do both sides, then let it sit in the shop for a day, before going to cut it to width, then let it shit, then cut it to length...sort of a way to making sure you aren't releasing too much pressure at once?
Contributor
If it's in equilibrium with your shop, there will be no pressure to release, at least none due to differential moisture. But I've heard/read that advise and there's certainly no harm with that approach. I've just never found it necessary with well conditioned wood.
John
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