Drying wood by boiling in salt water

Hi all,

does anyone have experience with accelerating the drying process of wood by cooking it in salt water?
This is apparently a scandiavian technique, used for traditional cups.

I want to use some 3-5 cm thick slices of a log for a project and had the chance to get some freshly cut ones. Found on the internet, that cooking in salt water drains all the stuff (proteins?) from inside the wood, so that only salt water remains, which should then dry more quickly.
It might be comparable to driftwood, which has been in water for a long time and therefore completely cleansed.

So I took the log slices and started cooking. I used approximately 800g salt on 5-6 liters of water.

After 2-3 hours it looked like this: (The liquid can supposedly be used as stain)

After the process there were already cracks in the center, so I most likely failed here :roll_eyes:.

Well, this was a quick shot based on loose information, but anyway, if someone has done this successfully I’d be happy for advice on this topic.

Regards
Nils

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+1 for the effort! This is what dried wood can look like no matter how long it takes to “dry.” Cutting it in sliced slabs will certainly help that along.

Perhaps the Scandinavians only did this on the un-sliced logs where there was more support for the internal fibers?

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For a discussion of this sort of thing and associated concepts see:

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Our Scandinavian wooden cups are usually made from birch burls and boiling them in salt water is done for several reasons;

  1. Kill the wood, i.e. stopping the growth.

  2. Kill any fungus in the wood, birch is especially susceptible to staining from certain types of fungi.

  3. Make the wood dry faster. Here is the caveat: the wood must be wet enough to be easily carved/hollowed out, but it must not dry too quickly or it will crack. This is usually done by storing the burl in wet towels or in the freezer in-between work sessions.

  4. Boiling in salt water makes whatever you drink out of the cup taste horrible for a good while :nauseated_face:

And if the wood already has cracks in it, boiling will not stop it from cracking when it dries.

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You can dry wood, if small enough, in the microwave. Just do it slowly. If you go too fast it will crack. If cracked you can epoxy to fill the cracks.

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Thanks for the answers!

@WillAdams, I put it on my shopping list.

@BrokenEndmill, do you have an estimate of how much faster boiled wood will dry? Does the wood become more flexible, so that it is less likely to crack?

And @gdon_2003, that’s a good suggestion. I think I will go for the risk of drying it faster (by putting it close to a radiator) and then repair the cracks. It should be sufficient for my project.

Btw., I put another slice into salt walter over night without boiling. The water is starting to get the same color, so the heat is probably not necessary.

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Adding heat and moisture to a piece of wood will make it pliable, like steaming long strips of wood used in strip-wood canoes.

I have also head that boiling the wood relieves tension in the wood and thereby preventing cracking.

In school we used to re-boil our cup workpieces before working on them again, because it would take more than the one hour of wood shop class a week to finish carving the cup. After boiling, the wood carved like hot butter.

About drying times, I have no accurate data on how faster it dries, but a piping hot piece of wood will steam off moisture pretty fast.

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:neutral_face:every quick drying technique has its own risk…case hardening, cracks, and checks to name a few. With cookies(end grain cross sections) you will never be able to dry it without cracks unless you dry the entire log completely before you start to make the cookies…then your looking at about 6 months per inch. But if cracks are ok…stick it in the oven around 200 for a day and let cool slowly. Alcohol is another quick way…I can go on and on…but I have found patience is the best method…

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When I posted here, I also decided to compare the drying of boiled slices next to a heat source (radiator) and in a less “aggressive” location.

I forgot to weigh the slices before boiling, but here are some weights in grams:


The only survivor is slice D, it has no cracks at all. The others are now Pac Man. So I got a tiny success here.
I leave this detailed data open for scientific interpretation :stuck_out_tongue:

Anyway, I started reading the book @WillAdams suggested and I now find myself in the same position as the author when he was a teenager. I am only 15 years late!

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