Monday, December 24, 2012

Danish Soap Finish

One of the most mysterious things about Danish modern furniture to me when I started making it was this strange soap finish that is talked about so often. I wondered, "What is this all about"?

Well, the easy answer is that it is a soap that is simple washed onto the wood surface. You may wonder how that protects the surface, though. Basically, soaps traditionally where made of oils of some sort or another. Your grandma or great grandma would have used "ivory" soap flakes that where made from vegetable based sources, palm and coconut oils usually. Everything from cloths to who knows what was washed with it.

Why use soap to protect wood surfaces? Wood has pores and those pores will get clogged with dirt and oils from use if not protected. Soap clogs those pore and keeps the dirt and oils out. Also being soap it also releases dirt and oils easily thus keeping it off of the surface.

Wood also benefits by have a finish that slows the exchange of moisture from the wood to the surrounding atmosphere, thus keeping it more stable. Soap finishes aid in doing this like other finishes though to a lesser degree.

The biggest advantage, I believe, is that it leaves woods like white oak and ash looking as natural as the raw wood itself. As a woodworker I love the organic feel this gives a piece. The soap finish is also incredibly smooth to the touch and ages so beautifully.

Some suggest that soap finishes are a lot of maintenance. I have found that since they age nicely I really don't do anything to maintain their appearance. If it does get soiled, simply wiping the surface with a damp cloth will usually remove whatever is unwanted. Wiping the surface with more of the same soap will freshen it up as well. In Denmark this is often used to finish floors even. I think that attests to its durability and effectiveness as a finish.

I purchase my soap flakes from a U.K. based producer. www.msodistributing.com currently can supply this in the US.


Here is how I prepare my soap finish. I mix boiling water and soap flakes in equal parts, 1/1 ratio. If I am making a large batch I will reduce the water a bit. I only want enough water to dissolve the flakes and it should create a whipped cream like consistency when mixed together but with a thicker body to it, not so airy.

First measure out your flakes and then pour the boiling water in equal parts over the flakes. Let that set long enough for the flakes to absorb the water and it will get a translucent appearance and will become sort of jelly like. Now mix in a bowl until you get the consistency I mentioned above. See photo below.





You can now place a small amount inside a lint free white cotton cloth that is folded over itself. Squeeze the soap through the fibers and to the outer surface. This will thoroughly saturate the cloth with soap. Now wipe it on the surface of your wood. Put on enough to fill the pores. Don't let it cake on the surface, though. Once it is dry you can knock down any raised grain with 220-320 grit sand paper. Apply one more coat and that is usually sufficient. Finish by buffing with a soft cloth if desired.

To freshen up your finish follow the same steps. If you have a set in stain you can try pouring some boiling water on the spot. The soap will often force the stain loose. Let it dry and reapply a finish.

A note of caution; Do not wet end grain surfaces to heavily. These areas absorb more water than the face grain and can crack if continually saturated. Thus it is best to make your soap with less water and more like a paste. Also coat both sides of a panel, such as a table top, evenly so that it will reduce the potential to cup or warp.


8 comments:

  1. Caleb I find this very interesting and have an idea to use this on a stool I will be making soon. Have you used it on woods other than white oak and ash? I'm thinking of walnut, cherry or maple.

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    1. Ray,

      This is a good finish for light colored woods in particular. Beech and maple would do well with it. I never do walnut but choose danish oil for that. I think cherry would look better with another finish as well. Just my thoughts.

      Peter had done some soap over darker milk paint while he was here last teaching a class. He was really excited about it. Maybe we can get him to post his thoughts on it.

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  2. I was searching the internet for soap flakes and found palm kernel flakes. Are these flakes similar or at leas a viable alternative?

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    Replies
    1. Greg,

      I am not sure on that one. Maybe if you sent me a link I might be able to tell.

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  3. I'm the the process of making a mid-century (Hans Wegner CH3238 inspired) hard maple kitchen table. I'm about to start the finish.

    1) I love the look of a soap finish, but am concerned about durability. I expect the table will end up, sooner or later, having nasties like red wine spilled on it. Is it pretty stain resistant?

    2) My intention was to sand it to 220, wet it, sand it with 220 again, then proceed through sandpapers to around 400. Will the wood still accept the soap if I sand it that fine?

    If it's not too much trouble could you drop me an email with your response? mailto:bschless@rasco.com

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    Replies
    1. Beau,

      I have not soaped maple before so I can’t say how well it will take the soap at 400. The idea though is to clog the pores with the soap more so than have the wood absorb the soap.

      A soap finish is not resistant to stains very will. If you get blueberry, raspberry or wine on it expect to have a stain. You can pour some boiling water on a stain and it will lift it out a bit better and then go back and soap it again. There is always the option of sanding it out as well. Not a big deal except that area won’t be oxidized as much as the surrounding wood. The old and new finish however will blend just fine.

      Hope that helps some.

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  4. Well, this looks fun but I'm just going to settle with the contemporary way of buying a soap. Much more convenient. Sorry no offense but great post.

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