Wood processing techniques

I cut the walnut. How do I dry it so it doesn't crack?

I received the same question, from 2 different people, within 2 months. This convinced me that an article about drying wood naturally "at home", with the usual means in a household, could be of interest to many people. But first of all you have to know that walnut, in Romania, is a protected species and you need permission to cut it. Approval is also needed for the one in your own backyard.

Nucul is a hardwood. Drying such wood causes very high stresses inside it, which can lead to cracks.

natural drying of wood
photo source: wood-database.com

That's why there are a few rules to follow.

  • The trunk should be turned into planks as soon as possible after the tree has been felled. The thickness of the plank is variable and depends on what is to be obtained from it.
  • Please note that by drying the dimensions of the board decrease. Cut the planks slightly larger than the size you need.
natural drying of wood
photo source: lumberjocks.com
  • To prevent cracking, the ends of the planks are sealed with paraffin, special oils or a diluted primer. This will slow the escape of moisture from the wood and reduce the risk of cracking.
natural drying of wood
photo source: wood-database.com
  • Depending on the time of felling, the humidity inside the tree can reach 200% (spring). It must be removed slowly to avoid tension inside the wood. Felling during the dormant period (November-January) is recommended because the amount of water in the tree is lowest.
  • The peel is not removed during drying. It acts as an insulator, slowing down the escape of moisture and reducing tensions.
  • If there are areas attacked by insects or mould, they must be removed so as not to contaminate the rest of the wood.
  • The planks are stacked 30-40 cm from the ground. Between the planks, 8/10 or 10/10 mm wooden battens are placed perpendicular to the plank. These allow air to circulate around each plank. A fairly heavy weight (100-200 kg) is placed on the stack so that the wood does not warp during the drying period.
natural drying of wood
photo source: mountainheardwoodworks.com
  • It is recommended that the stack be made under shelter, under a shed or even in a barn. The cellar can also be used, as it has constant temperature and humidity. Ventilation is very important to promote drying. A fan can be used to increase air movement. If it is not possible to make the stack under cover, it should be covered (with sheeting, plexiglass or other protective material).
natural drying of wood
photo source: forum.woodenboat.com
  • The natural drying of wood takes place slowly and depends on the thickness of the plank. One year is needed for every 2.5 cm (1 inch) of thickness. Some experts say one year is needed for every inch plus one more. So a 2 inch plank needs 2+1=3 years, a 3 inch plank 3+1=4 years and so on.
  • The natural drying process stops when the wood has reached equilibrium. The equilibrium moisture content depends on the humidity of the environment. In our country, the equilibrium humidity is around 12%. If you want to lower the humidity below this value, you need to take the wood into a heated room.
  • Equilibrium moisture is determined by measuring the internal moisture of the lumber. It is reached when several consecutive measurements show the same value.
natural drying of wood
photo source: bizator.com
  • To achieve good results when naturally drying hardwoods, you should not cut young trees, avoid knots as much as possible and ensure that the wood has no growth defects.

I am convinced that following these recommendations will result in very good quality timber.

Of course there is also the possibility that forced dryingin special dryers. In this case the drying time is significantly reduced.

If the wood is not well dried, the consequences can be very unpleasant. The wood may crack or warp, and the object made from such wood is totally compromised. More information on equilibrium moisture can be found at here.

About the author

Mihaela Radu

Mihaela Radu is a chemical engineer but has a great passion for wood. She has been working in the field for more than 20 years, wood finishing being what defined her during this period. She gained experience working in a research institute, in her own company, as well as in a multinational. She wants to continuously share her experience with those who have the same passion - and more.

36 comments

Add a comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

  • I read with great attention and share every posted , I love it and hope you will not stop posting ... If you can alrticles with wood finishing . Thank you

    • Thank you. I promise I will write as many articles about finishing as I can. 🙂 If you are interested in a specific topic please let me know. I will be happy to develop it into an article.

  • Hello, very interesting topic and topical as far as I am concerned. I am going to cut a walnut tree and I would like to know if the wood can be dried as a log?
    Thank you

    • Hello. Being hardwood, large tensions appear inside when drying. Therefore, it is almost impossible to dry without cracking. It should be "sliced" immediately after cutting, to reduce tensions. The moisture content at the time of cutting also matters. In autumn and winter, the humidity inside is lower and tensions are lower. The age of the tree also matters. When it's young it cracks more easily. It also depends on what you want to do with it. In the past, in the country, people used to cut the acacia trees (hard, very tough) and use them immediately for the load-bearing structures of their houses. Over time cracks appeared inside the posts and beams, but they were not disturbing.
      I wish you success!

  • Very useful article, as a summary it's good to
    - we cut the tree during the resting period of the wood, i.e. autumn and winter,
    - after cutting it is best to cut it to the desired thickness plus a tolerance that will decrease in the drying process,
    - will not peel off the skin
    - after cutting it will be stacked in the stack with 5-10cm spacers and the end will be "insulated" with paraffin or a diluted primer.
    - drying time for every 2,5 cm = 1 year + 1 year for balancing the interior humidity in the whole wood surface. for a 10 cm thick post the minimum drying time according to the specialists is 4+1 = 5 years.

  • Hello,
    If I cut the walnut on Saturday, how long does it take to slice it?
    Is 2 weeks too long to sit in the garden?
    Thank you.
    Have a nice day.

    • The faster you slice it the better. The fact that you sliced it at this time is good, the water content is lower. It is good to hurry up with the slicing, because the recommendation is to do it immediately after slicing. Then seal the ends of the shingles with paraffin.
      Good luck!

  • Mrs Mihaela
    Can you give me information on where I could buy exotic wood (or waste -minimum 30 x 20 mm)?
    Short Dan

    • It is an Anglo-Saxon unit of measure so the original name is INCH, pronounced in Romanian as "inches".In German, the inch is called "zoll".In Romanian both inch and zoll are neologisms and are used depending on the circumstances.

    • Hello.
      Unfortunately I can't help you much. The old veneer factories have disappeared (see Furnimob in Constanta), and the new ones are few (Rariwood, near Arad) and little interested in such collaborations. I'll look into it and if I find something I'll let you know.
      All the best!

      • Hello. Please recommend me in Cluj where to take the walnut trunk to be cut properly. I would like to make tables out of it unprocessed just varnished or with polymer resin. What do you think about using resin? Contact Oana 0742038131. Thank you.

  • Good evening,
    I find an inexhaustible source of interesting articles on your site and thank you for that!
    I am writing to you, however, with a request for guidance.
    Two weeks ago, I took a holly tree trunk out of the wood shed and tried to turn it into a decorative object. As soon as I took it out of the shed I peeled it and brought it "to the block" to paint it.
    But I was surprised to find that the wood had cracked from top to bottom and I could not use it as I had planned.
    As I do not have the possibility to apply a complex wood drying process I want to ask you if there is another "home" action that I can perform to prevent wood damage (cracking) after peeling.
    Should I apply a certain solution/material immediately or should I simply give it time to dry naturally?
    Thank you for your time!

    • Hello.
      There must have been a big difference in humidity between the shed and the apartment. The wood had probably not been cut long and still had a high water content. Especially if it had been cut recently, in the middle of the growing season. The water came out much quicker and the lack of bark flayed. This caused tension and the wood cracked.
      Salcam is a very hard wood and the stresses that occur are much higher compared to other woods. You should have left it with the bark, drying would have been slower. You could try sealing the grain ends (the sections perpendicular to the log) with an aracite solution (aracite dissolved in water at 10-20%), paraffin or a very thin layer of varnish (very thinned varnish). That way the water comes out more slowly and you have a better chance of it not cracking. It also matters a lot when the tree was cut.
      Thank you for your appreciation.
      All the best!

  • Good evening,
    I received a walnut log with the bark on it that has been sitting in a shed for 2 years. I managed to slice it to 5cm thickness. I intend to build an epoxy resin coated countertop. If it is fully coated in epoxy, is there still a danger of cracking, bending the wood?

  • Cut when there is no more vegetation, up to the swallow hole. Slice and store at plus 5 degrees, otherwise it will crack from frost...in summer it should be kept cool (max 20 degrees).

  • Hello, I appreciate the information posted and enjoy reading. I would need some advice if possible. I have a chopped cherry tree, 2 logs about 1,5m long and 15-20cm thick. My desire is to process them on lathe, grain bowl etc, but they crack shortly after I start processing. Can you direct me to a drying method that will help me get rid of this problem? Thanks, Horatiu

    • Hello!
      Thank you for your appreciation.
      Cherry is a wood that does not develop very high tensions. However, if the water content is high (depending on the period of felling), and if it is uncut, tensions appear. You should coat the ends with paraffin or a diluted water-based primer. This will slow down the moisture coming out. The recommendation is to leave it with the bark on, but there is also a risk of insects under the bark getting into the wood. Do not leave it in the sun and keep it in well ventilated areas. It would be good if you had a well-ventilated shed or cellar.
      There are methods of rushing water out of green wood or stabilising it, but they are difficult to apply to large pieces of wood. Find some of these methods in the link below.
      I hope you found it useful.
      All the best!
      https://revistadinlemn.ro/2018/06/13/stabilizarea-lemnului-verde-pentru-evitarea-craparii/

      • Thank you very much for your answer. The bushes with bark and healthy but unfortunately have been in the sun a lot. I will cover the ends and use the garage for storage, I just don't think it is ventilated enough. I'll give it a try. Thanks

        • Do not close the garage tightly. Always leave a window or door unlocked. That way, air exchange will take place (even if more slowly) and the wood will dry out. In this case, a very strong draught is not recommended either.
          All the best!

      • In what proportion should the primer be diluted? Can thinner-based primer be used? If I use aracite, in what ratio aracite/water? I have some walnut logs recently cut and it will take a while to cut them into planks and I would like them not to crack. Thank you!

        • The important thing is to make them more fluid so that they are absorbed by the wood and close the ends of the fibre. You can use a 1:1 ratio for the aracite, i.e. one part water to one part aracite. For primer, if it is more fluid, put 2 parts primer to 1 part thinner. If the primer is quite viscous you can use the same ratio as for the aracite.
          Good luck!

  • Good evening!
    Very complex and useful your articles!
    I have a request if you can help me with some advice.
    Two weeks ago I cut a walnut tree and sliced it to 8 cm thick in order to make table tops. It is currently drying naturally in the barn, on the hull, with the stems covered with aracet. I should mention that during the cutting process it could be observed that the wood contains a lot of water. The question is how should I proceed with forced drying so that there is no loss?
    ( natural drying about 1 year and then dryer or I can put it in a steamer now - for color - and then in the dryer )
    Thank you?

Categories

Subscribe to newsletter

Newsletter Friday morning
Information and advice from the experts

en_USEnglish