Easily the most emails I receive from people who are having problems with their wood and or their wood projects are issues that come from using wet wood. That is ... wood that has a moisture content above the recommended 9% that is often used as the guideline for making quality furniture. Most who I talk to don't even know what the moisture content of their wood is and very, very few own moisture meters.
Watch it on Youtube: https://youtu.be/tNHcNjTrTf0
Moisture content is almost never talked about but it is THE most important issue when you are buying wood because almost everything that falls out of your builds that becomes problematic is a result of the high moisture contained in your wood.
What is very popular, and has been for a long time, is using construction grade 2x4s, 2x6s, and other construction grade lumber to make things. I understand that many people want to build things from wood and practice their woodworking, and inexpensive lumber is one good way of doing that. Where issues with doing this surface are when the expectation of what you are building does not match the reality of what takes place as the wood dries and often cracks, warps, joints come loose and the finish starts falling off in places or it starts to discolor because is mold or mildew.
All of these are symptoms of using wet wood, but hey! ... if you know all this ahead of time, and your goal is just to make things from 2x4s by all means do it ... just don't necessarily expect good long-term results from your project. Maybe go ahead and make things but just alter your expectations on the outcomes and what you want to build. We all love to build things but trying to build quality furniture from construction grade 2x4s is usually a miss match of wood to project.
I went to the lumber store to pick up some wood for this video, knowing I would be purchasing wet wood, but I brought my moisture meter along just to see how wet the wood is. The only wood they had in 8-foot length was marked SPF, which stands for Spruce Pine Fir, and that means the lift of lumber could contain any or all of these species of wood. As it turned out the pile was ALL Spruce, which is a very soft wood and even softer when wet, or "green" as it is referred to.
I looked through the bundle and the wood looked OK in terms of knots, few of them but tight knots as for the straightness, I have learned that you really can't judge too much on straightness until the wood is dried out and you certainly can't pull straight ones out of the middle and hope they will stay straight ... some will some won't, all depends on the tree and the amount of moisture it contains.
So I checked a few and they were all somewhere between 18% and 19% so surprise there.
Quality of Wood
When we are buying wood, we need to try to purchase wood that matches the kind of projects we are making, or to understand that if we making utility items, the quality of the lumber does not need to be as high as if we were building a bookcase for example.
When you are looking for lumber, there are 2 things you need to know,
1) what are the dimensions of the wood and
2) how wet is the wood
For the latter, you need to have a moisture meter. Now you can get by without one, but you can also get by without a table saw too. If you are serious about woodworking and want to eventually produce some good quality pieces, you need to purchase good quality lumber, and knowing the moisture content will be paramount.
The picture below is the moisture content of one of my 2x4s after it had been in my shop for about a week or so.
I am always amazed at how many woodworkers do not own a moisture meter, these are critical tools for knowing the state of your wood.
There are both "pinned" moisture meters and "pinless" and anyone serious about woodworking would be selecting a pinless moisture meter because they are faster to use and you don't need to ask the wood owner, every time you want to check lumber and poke holes in their wood to find the moisture content. As a woodworker, you probably wouldn't appreciate finding little holes in your lumber after you got it home and started jointing and planning it only to find little holes from someone else's moisture meter.
Below is the picture of one of the pinless moisture meter from Wagner that is listed in the Woodworkweb Amazon Store
The problems with using wet wood for furniture making are long and complex, mostly because wood is always moving. When trees are cut down they are often in excess of 40% moisture content and to dry them down to the often recommended 9% means a lot can happen to the wood, like cracking, bending, warping, knots falling out, wood shrinkage as well as hardening of the wood.
Joining wood together can be one of the most challenging aspects of using wet lumber, there just are not a lot of good choices when you know wood is going to shrink for sure, and possibly also warp, bend and crack.
Pocket hole joinery is currently a very popular way of joining wood but when you are using softwood, which construction grade lumber is, and it's wet, which makes it even softer, pocket hole joinery would be the weakest joint you could select. The other factor is that often using screws in wet lumber invites even more cracking as the wood dries so pocket holes are not the best selection, aside from the fact they leave the telltale signs of what they are.
Some people who own joiner tools like those with loose tenons or even biscuit joinery will be wondering about these.
Biscuits were never intended as a joinery solutions for natural lumber but many people have adopted them. The real problem with biscuits is that they only connect such a small amount of wood there really is little strength in them. For isolated use in something that doesn't move you make get some use from this.
Loose tenon tools and similar, especially the larger size may be a useful joint
Dowels, particularly the larger half in size, and mortise and tenon are probably near the top for joinery strength.
The very best joint for wet wood is lap joints, and that is because of the large gluing surface. The glue seems to adhere OK to wet woods, but be careful, there is a limit to what ordinary yellow carpenters glue will withstand. There are glues specifically made for gluing wet wood, but there are very expensive and are primarily used in the boat repair field.
So if you are using wet wood and you want something to last, use glue and lap joints as much as you can.
Finishing wood is easy, there are lots of great products ... finishing wet wood is a whole other issue. The first step in finishing if you want to alter the color of the wood is to add a colorant which is often "stain" which is basically crushed rock mixed with some sort of oil and spirits. We all know water and oil don't mix so what you can end up with is a stain in very wet wood which can give a blotchy look and take days to dry. The other thing you can use is a wood dye, which is often mixed with water, which means it doesn't impede the drying of the wood, and it happens to mix with the water that is already in the wood. If all you are going to do is "color" the wood and not put a top finish on, you may be fine ... may be.
If on the other hand, you are wanting to put a top coat finish on, here is where most of the problems with wet wood will show up. There are basically 2 kinds of top finishes.
Film Finishes, like Varnish, Polyurethane, and even Paint. All of these finishes lie on top of the wood and as they dry they adhere themselves to the wood. If the wood is wet, that wetness is going to wick out of the wood, no matter what, and in the process, it will "lift" any of the films finishes right off the wood. I have heard of some coming off in sheets. Coating wet wood with any film product is an invitation for problems.
Oil Finishes are the second kind of finish and these are things like Tung Oil or Linseed Oil (linseed oil is marketed under many different names, it's still basically linseed oil) and something very popular lately called hard wax oils, which are similar to pure oils, but with some more additives. All of these oils have a bit of an ability to allow moisture to pass through them so they will not lift, but I have seen some that seem to trap moisture within the surface and can mix with molds and mildews to discolor the wood, which is not great either because then the wood needs to be re-sanded and resurfaced again ...
There is no "best" finish for wet wood, about the only thing you might be able to get away with is coloring using an aniline, water soluble dye.
Copyright Colin Knecht