Furniture Making

You are not logged in. [ Login ] Why log in
(NOTE: Login is not required to post)

Quickly reverse timber shrinkage?

Matt Cooper

Hi all, I'm looking for some advice about slightly increasing the moisture content of timber rapidly. I make circular tables that I edge with a steel ring. I'm really careful to dry the timber in my kiln prior to joining and cutting the boards to create the top, and I then roll a steel ring that fits very tightly. The timber I use is Norway spruce and I try to get a <7% surface/12% core reading with my moisture meter so that when the tables eventually go into a home they'll take on a little moisture over time but not shrink (resulting in a gap between the edging and the timber). This has worked so far without any issues, but I have one table top that's undergone further shrinkage after fitting the edgeband because I had to keep it in the kiln overnight to cure a finish. I didn't switch off the dehumidifier.

I am currently attempting to rectify the problem by putting the top back into the kiln and injecting steam to increase the RH, but I don't know whether this will work in the time I have left prior to meeting the deadline for shipping. The worst case scenario is that I roll a new steel ring to replace the current one, but I'm looking for something that's a fix for future instances of this problem.

These tables sell very well and I don't want to change the design or stop making them. Can anyone offer me some advice?

View higher quality, full size image (3264 X 2448)

3/14/17       #2: Quickly reverse timber shrinkage? ...
rich c.

With a moisture gradient between the core of the wood, and the surface, it's going to move. Steel frames and wood don't play well together. Wood is always going to expand and contract. No amount of kiln drying is going to stabilize it for no shrinkage in the future! It swells one time, it may crush some cells to stay in the ring, but then shrink away when the humidity drops. Especially considering those wide flat sawn planks. Quarter sawn would be a must for me, but if you don't want to see any gaps, you should run a rabbet around the table and have the wood set over a ring. I'd say you are still going to get some issues. Can't fool Mother Nature.

3/14/17       #3: Quickly reverse timber shrinkage? ...
David R Sochar Member

Rich is correct except for the part that "no amount of kiln drying will stabilize it for no shrinkage in the future". There is a way....

Get all your boards to a good 7-8% all thru the lumber, then build the table and finish it well. Then rush it to a museum with state of the art HVAC set to make stable humidity and temperatures. This preserves the art work that is often fragile and at risk with temperature and humidity variants.

You can see the old style chart recorders in the better museums as a means of protection and insurance. Newer ones are digital recorders, but they serve the same purpose. This what helps keep those 200 yr old pieces of furniture looking good. It can work for your tables also.

3/14/17       #4: Quickly reverse timber shrinkage? ...

Matt Cooper:

If I read your post correctly, you have a problem with one table because you made a variation in your production process to only this one table.

If you have had no issues in the past with however many tables you have built, perhaps the problem is confined to only this table and the single episodic variation from your standard production process.

In the States we say "If it isn't broke, don't fix it." You may come out ahead, from both a profit and stress standpoint, by rebuilding the errant table using your standard process and moving on.

I would only concern myself with this shrinkage issue if it proves to be replicated on tables that you have built using your standard process.


3/15/17       #5: Quickly reverse timber shrinkage? ...
Dave Nauman  Member


Polyethylene glycol? polyethylene glycol peg green wood stabilizer

3/15/17       #6: Quickly reverse timber shrinkage? ...
John Member

After looking at the table top I read your name and smiled. Anyway, I agree with the first couple of responses. No matter what you do the boards will expand/contract with changes in RH. There is no way to stop that. The way I would deal with the issue is make the steel hoop in two pieces, with one overlapping the other. Orient the ends of the hoops at the centerline of the table top. Attach each hoop to the boards but not to each other or, if you do, make sure that connection can slide. Now when the wood expands/contracts the hoop halves will move with it.


3/20/17       #8: Quickly reverse timber shrinkage? ...
Matt Cooper

Thank you very much for the responses, guys! Quite right about the change in the production process for this top, I shouldn't have put it in the kiln with the ring on it - bad idea.

I have considered putting a flat ring into a rabbet to hide gapping and help support the edge ring, but rolling one accurately with my "hand mangle" would be very challenging indeed, and it would add cost to the customer. I have also considered making the ring in two or more parts, but because all boards are able to contract at the ends then isolated gaps are still possible IYSWIM.

I've looked at PEG but I don't have any of the required equipment (vats etc) and can't dispose of the waste easily/cheaply, and in any case it ought to be unnecessary given that I've had no other issues (YET!) apart from the very first table I built this way (which has just come back to me for the second time for a ring refit... I learned a lot from this one).

I've decided to halt production for a few weeks so that the timber that's in the kiln right now is dried to a point where it has little or no gradient, and I think this will produce the safest material to work with. Fingers crossed.

Does anyone have a suggestion for the least permeable finish available (in the UK if possible)? I'm thinking that if I can slow moisture exchange as much as it possible (by coating all surfaces including end grain with it) I can mitigate the risk of movement even further...

"After looking at the table top I read your name and smiled" - haha, well spotted ;-)

3/20/17       #9: Quickly reverse timber shrinkage? ...
John Member

Your wood is going to move with changes in RH no matter how much you dry it. The only way to stop wood from moving is to keep it at constant RH. Since that's not practical in any setting other than a museum you need to adapt the ring to accommodate the wood. The other way around will never work with that design. Finish only slows the exchange of moisture, it won't stop it.

You need to make a design change in order to solve the problem.


3/20/17       #10: Quickly reverse timber shrinkage? ...
rich c.

Yep, no matter what you do with the kiln or finish, the rings are going to be loose with flat sawn stock during heating season. Always, always, always! People crossing the prairies in Conestoga wagons were always glad to ride through water once and a while. The rims would tighten back up on the wheels.

3/26/17       #11: Quickly reverse timber shrinkage? ...
Jason Chaplin

you should look at using acetylated wood like accoya for your table tops

It will add cost to the product but if it lives upto the specs supplied by the manufacturer
it will solve your problem

4/25/17       #12: Quickly reverse timber shrinkage? ...
Rob Scaffe  Member

I agree with the other post regarding the inevitability of wood movement. To answer your question regarding a finish, de-waxed shellac provides the best barrier to water vapor. You can then finish with whatever finish you like as most anything will stick to it.

5/3/17       #13: Quickly reverse timber shrinkage? ...
MarkSindone  Member


Yes, I had the same question in my mind too. Why this particular table alone? If this problem had not occurred before, then your procedures for this isolated incident could be overlooked. To save time, I would simply use a new steel ring to fit into the shrunk diameter of the wooden table. I have a similar storage cabinet made of this wood and it still shrinks occasionally but not so obviously. So, I guess it is just inevitable nature doing its course.

  • Post a Response to this thread
  • Notify me of responses to this thread
  • Subscribe to email updates on this Forum
  • To receive email notification of additions to this forum thread,
    enter your name and email address, and then click the
    "Keep Me Posted" button below.

    Please Note: If you have posted a message or response,
    do not submit this request ... you are already signed up
    to receive notification!

    Your Name:
    E-Mail Address:
    Enter the correct numbers into the field below:

    Date of your Birth:

    Return to top of page

    Buy & Sell Exchanges | Forums | Galleries | Site Map

    FORUM GUIDELINES: Please review the guidelines below before posting at WOODWEB's Interactive Message Boards (return to top)

  • WOODWEB is a professional industrial woodworking site. Hobbyist and homeowner woodworking questions are inappropriate.
  • Messages should be kept reasonably short and on topic, relating to the focus of the forum. Responses should relate to the original question.
  • A valid email return address must be included with each message.
  • Advertising is inappropriate. The only exceptions are the Classified Ads Exchange, Machinery Exchange, Lumber Exchange, and Job Opportunities and Services Exchange. When posting listings in these areas, review the posting instructions carefully.
  • Subject lines may be edited for length and clarity.
  • "Cross posting" is not permitted. Choose the best forum for your question, and post your question at one forum only.
  • Messages requesting private responses will be removed - Forums are designed to provide information and assistance for all of our visitors. Private response requests are appropriate at WOODWEB's Exchanges and Job Opportunities and Services.
  • Messages that accuse businesses or individuals of alleged negative actions or behavior are inappropriate since WOODWEB is unable to verify or substantiate the claims.
  • Posts with the intent of soliciting answers to surveys are not appropriate. Contact WOODWEB for more information on initiating a survey.
  • Excessive forum participation by an individual upsets the balance of a healthy forum atmosphere. Individuals who excessively post responses containing marginal content will be considered repeat forum abusers.
  • Responses that initiate or support inappropriate and off-topic discussion of general politics detract from the professional woodworking focus of WOODWEB, and will be removed.
  • Participants are encouraged to use their real name when posting. Intentionally using another persons name is prohibited, and posts of this nature will be removed at WOODWEB's discretion.
  • Comments, questions, or criticisms regarding Forum policies should be directed to WOODWEB's Systems Administrator
    (return to top).

    Carefully review your message before clicking on the "Send Message" button - you will not be able to revise the message once it has been sent.

    You will be notified of responses to the message(s) you posted via email. Be sure to enter your email address correctly.

    WOODWEB's forums are a highly regarded resource for professional woodworkers. Messages and responses that are crafted in a professional and civil manner strengthen this resource. Messages that do not reflect a professional tone reduce the value of our forums.

    Messages are inappropriate when their content: is deemed libelous in nature or is based on rumor, fails to meet basic standards of decorum, contains blatant advertising or inappropriate emphasis on self promotion (return to top).

    Libel:   Posts which defame an individual or organization, or employ a tone which can be viewed as malicious in nature. Words, pictures, or cartoons which expose a person or organization to public hatred, shame, disgrace, or ridicule, or induce an ill opinion of a person or organization, are libelous.

    Improper Decorum:   Posts which are profane, inciting, disrespectful or uncivil in tone, or maliciously worded. This also includes the venting of unsubstantiated opinions. Such messages do little to illuminate a given topic, and often have the opposite effect. Constructive criticism is acceptable (return to top).

    Advertising:   The purpose of WOODWEB Forums is to provide answers, not an advertising venue. Companies participating in a Forum discussion should provide specific answers to posted questions. WOODWEB suggests that businesses include an appropriately crafted signature in order to identify their company. A well meaning post that seems to be on-topic but contains a product reference may do your business more harm than good in the Forum environment. Forum users may perceive your references to specific products as unsolicited advertising (spam) and consciously avoid your web site or services. A well-crafted signature is an appropriate way to advertise your services that will not offend potential customers. Signatures should be limited to 4-6 lines, and may contain information that identifies the type of business you're in, your URL and email address (return to top).

    Repeated Forum Abuse: Forum participants who repeatedly fail to follow WOODWEB's Forum Guidelines may encounter difficulty when attempting to post messages.

    There are often situations when the original message asks for opinions: "What is the best widget for my type of shop?". To a certain extent, the person posting the message is responsible for including specific questions within the message. An open ended question (like the one above) invites responses that may read as sales pitches. WOODWEB suggests that companies responding to such a question provide detailed and substantive replies rather than responses that read as a one-sided product promotion. It has been WOODWEB's experience that substantive responses are held in higher regard by our readers (return to top).

    The staff of WOODWEB assume no responsibility for the accuracy, content, or outcome of any posting transmitted at WOODWEB's Message Boards. Participants should undertake the use of machinery, materials and methods discussed at WOODWEB's Message Boards after considerate evaluation, and at their own risk. WOODWEB reserves the right to delete any messages it deems inappropriate. (return to top)

  • Forum Posting Help
    Your Name The name you enter in this field will be the name that appears with your post or response (return to form).
    Your Website Personal or business website links must point to the author's website. Inappropriate links will be removed without notice, and at WOODWEB's sole discretion. WOODWEB reserves the right to delete any messages with links it deems inappropriate. (return to form)
    E-Mail Address Your e-mail address will not be publicly viewable. Forum participants will be able to contact you using a contact link (included with your post) that is substituted for your actual address. You must include a valid email address in this field. (return to form)
    Subject Subject may be edited for length and clarity. Subject lines should provide an indication of the content of your post. (return to form)
    Thread Related Link and Image Guidelines Thread Related Links posted at WOODWEB's Forums and Exchanges should point to locations that provide supporting information for the topic being discussed in the current message thread. The purpose of WOODWEB Forums is to provide answers, not to serve as an advertising venue. A Thread Related Link that directs visitors to an area with inappropriate content will be removed. WOODWEB reserves the right to delete any messages with links or images it deems inappropriate. (return to form)
    Thread Related File Uploads Thread Related Files posted at WOODWEB's Forums and Exchanges should provide supporting information for the topic being discussed in the current message thread. Video Files: acceptable video formats are: .MOV .AVI .WMV .MPEG .MPG .MP4 (Image Upload Tips)   If you encounter any difficulty when uploading video files, E-mail WOODWEB for assistance. The purpose of WOODWEB Forums is to provide answers, not to serve as an advertising venue. A Thread Related File that contains inappropriate content will be removed, and uploaded files that are not directly related to the message thread will be removed. WOODWEB reserves the right to delete any messages with links, files, or images it deems inappropriate. (return to form)