Thick Dried Cherry
Thoughts on drying a large chunk of Cherry in order to make a custom clock, including a brief discussion of alcohol drying methods. March 26, 2013
Question
I thought I would like to learn about woodworking and make a mantle clock but I am learning that it is impossible to find a piece of dried cherry that is six or seven inches thick. Is it possible to dry a piece 24 x 13 x 7? I would like to know if it’s possible to get a piece this big that can be worked.
Forum Responses
(Sawing and Drying Forum)
From contributor Y:
I have dried cherry larger than that. You have asked two questions - can it be worked? Of course it can, all you need is the proper tools.
From Gene Wengert, forum technical advisor:
It is very difficult to dry this thickness in cherry (and some other species too). What is likely is some fine interior checking, along with several years of drying time. It is also likely that the core will not be as dry as the shell. For this reason many people will take a large piece, cut it into several thinner pieces, then dry it and then glue it back together in the order it was sawn to give a fairly good looking piece free of defects and dried in a reasonable time.
From the original questioner:
Contributor Y - I am encouraged by your success. I have been hearing that a piece that thick would never give up all the water and it would check and have other defects. I have asked many wood suppliers I found on the Internet.
Gene – your idea is good about gluing two pieces together. It would sure be elegant to make this project out of only one piece.
From Gene Wengert, forum technical advisor:
Short pieces do dry more easily. If you are in the mood for experimenting, you might try soaking the piece in alcohol for a while and then drying it. This approach does work well; I can probably find some more details if you want to try.
From the original questioner:
Contributor Y - did you have internal checking problems? Did you kiln dry it? How about this: I'll find a thick piece and cut out some of the wood from the slab to make it easier for the moisture to leave it. I'll wax the ends and dry it slow.
Gene - alcohol, you say. Would the entire piece need to be immersed in a big tub?
From Gene Wengert, forum technical advisor:
First, just to make sure you understand: The alcohol is for the wood. Alcohol replaces the water, so if you put the wood in a bag with just a little alcohol, soon it will be severely diluted and no longer effective. So, you need a large container and then submerge the wood in adequate alcohol. Keep it covered to avoid evaporation. Keep it at room temperature.
Once the wood is saturated with alcohol, which replaces the water but without shrinking, then you take it out of the alcohol and let the alcohol evaporate (not in a closed room or where it might pose a fire danger). There is not a lot written about this method, so you will have to try a few different procedures until one works for you. Vacuum drying is a good option for thick lumber, but this might be a bit too thick.
From contributor Y:
You need to think about this in a new way. Since you are making a clock, and ultimately the center will be hollow, hollow it out while the wood is green. Get it to near net shape with a uniform wall thickness, and then dry it slowly over time. When you get it to about 10-12% MC machine it to your finished dimensions.
From the original questioner:
Gene, thank you for the clarification. I think I understand. The alcohol replaces the water then the alcohol leaves the wood very quickly.
Contributor Y - It is interesting that you mention carving a "near net" shape while it is still green because I just had the same idea yesterday while speaking with you guys. As a matter of fact I made some preliminary sketches to help me plan. After every cut I could seal the sides to avoid checking. I am willing to go to a lot of trouble to achieve a quality result. I am dreaming about a heirloom to give my daughter.
From contributor D:
Vacuum drying could do it but I can't do it. How's that for an answer? Let me explain. In a vacuum kiln you create a pressure in the water with heat, then with the vacuum you vaporize and remove the water. In a conventional kiln you are vaporizing off the surface. In vacuum drying you vaporize from the surface and below. The depth below depends on the density of the wood. With vacuum drying you can remove water much quicker but there is still a limit. The vacuum isn't going to have any effect on water in the center of a 7" thick piece of cherry. I would have to experiment to learn how much and when to add heat. It would be an interesting project if I had a tiny laboratory size vacuum kiln but I can't tie up one of my kilns for a piece of 7" cherry.
From the original questioner:
To contributor D: Thank you for explaining the vacuum drying process. You must experiment with large pieces and document your work so you can patent your process. My reason for wanting a large piece is that one solid piece seems much more elegant. More trouble, yes, but worthwhile things are always more trouble.
From contributor D:
I have experimented with Douglas fir up to 24" thick. I couldn't get it dry. I can dry up to 18". I have had investors who spent a fortune patenting the process to protect their investment worldwide.
I should add that it is difficult for me to patent a process when I have been giving away the details at forums for years. Also, I have cut all ties with investors. I really prefer to work with my small family business without the interference of investors no matter how deep their pockets are.
From contributor E:
To contributor D: If he rough cut it to size, allowing 1/2" in all dimensions of the final size, and cut the hole for the clock (also allowing 1/2" for drying) there would probably be no thickness over about three or four inches to any edge so vacuum drying would work then correct?
From contributor D:
To contributor E: It would be almost impossible to get that roughed out block to heat evenly. I would rough it out and then use the alcohol.
From the original questioner:
To contributor D: Douglas fir two feet thick, sounds like a pillar or mantle to me. Is it possible to keep such a large piece from checking? Thanks for experimenting so the rest of us can learn from you. I hope you are documenting your experiments and writing and publishing somewhere. If you don't, all your knowledge will be lost.
I am intrigued about alcohol assisted drying but because of my inexperience I want to be careful before I dunk an expensive piece of wood into alcohol. I trust it will not change the appearance or durability of cherry.
From contributor D:
To the original questioner: It's not possible to dry a 24" square without checks. Most pieces had heart center.
