Hot Danish Oil

This September, I attended the Port Townsend Wooden Boat Festival.  I’ve been going every year for a few years now and thoroughly enjoy the woodworking classes that they put on throughout the weekend.  One of the presentations that I went to this year was called “Non-Toxic Finishes” and was presented by Steve Habersetzer of the Port Townsend School of Woodworking.  Of all the presentations that I attended this year, this seems to be the one that has stuck in my mind.

Steve explained that any finishes with thinners in them caused him to have an allergic reaction.   If my recollections are correct, he advocated linseed oil.  The funny thing is that it was not the issue of toxic versus non-toxic that resonated with me, rather it was the method of application.  Perhaps this is common knowledge, but it was the first time that I had heard about heating a finish to apply it.  I just had to try it!

For some time now, my go to finish has been Watco Danish Oil.  I wanted to do a little experimentation with heating it prior to application.  First let me be clear, this is not what Steve was talking about in his presentation, as he was talking about linseed oil.  I don’t want to give the impression that this is a non-toxic finish, or that what I am doing here is in any way what he advocated.

On my workbench build, I have just finished making all of the chops for my vises.  They need to have the finish applied before I screw the vise face plates to them, and before I glue the leather to the inside faces.  I thought that this might provide an excellent opportunity to experiment with a heated finish.

I didn’t think that heating the oil directly would be safe.  I also didn’t think that the Mrs. would appreciate me using her crock pot, so I set of for Walmart in search of a cheap one for the shop.   I was quite surprised, I found a small 2 quart crock pot for  under $10, wow.

I filled it with water about 1/3 up from the bottom and then placed a jar lid in the bottom of the pot.  In a separate clean jar, I added the danish oil and a little bit of mineral spirits. I suppose that it was about 3 parts danish oil to 1 part thinner.  Perhaps I shouldn’t have added the thinner as I am adding another variable that I normally don’t use, but that’s what I did.  I capped the jar with a lid to prevent steam or condensation getting into the jar, but left the lid lose to allow for expansion or off-gassing.

I placed the jar into the crock pot and sat it on the jar lid in the bottom of pot.  This might not have been necessary, but I did it to avoid direct contact between the jar and the pot.  I put the glass lid on the crock pot and left it for about a half hour.

I heated the Danish Oil in a water filled crock pot.

I heated the Danish Oil in a water filled crock pot.

While it was heating, I spread out some newspaper on my assembly table (OK, so it’s really a table saw) and found some scrap off-cuts to set the chops on.

Hot oil ready to go on the vise chop.

Hot oil ready to go on the vise chop.

I started to brush on the oil and was a little surprised at just how fast it was soaked up by the wood.  When I apply danish oil, I always keep adding more as it soaks in.  I keep this up until the wood will absorb no more.  The fist application is always far heavier with danish oil, but this one really took a lot.

I kept applying the oil until it would absorb no more.

I kept applying the oil until it would absorb no more.

It took me about an hour to do all four vise chops. I kept cycling through them adding oil wherever it was needed.  That jar that I showed above?  I used it all.  I couldn’t believe that these four chops would soak up that much finish.  I left the surface wet for about 30 minutes and then thoroughly dried everything with a rag.  My experience has been that you don’t want to leave any wet oil on the surface or it will turn gummy.

These four chops soaked up that whole jar of oil.

These four chops soaked up that whole jar of oil.

With every thing wiped down, I left it to dry/cure.

I left them to cure.

I left them to cure.

I have since added a second coat, but this was applied or rubbed in with 220 grit paper.  That has been drying for two days now  and I’ll probably do a third coat with 320 grit paper tomorrow.  A fourth coat, rubbed in with 400 grit is usually as far as I go, other than some furniture paste wax when everything has cured.

I don’t think that there is sufficient information to make any conclusions yet about whether or not heating the oil yields a superior finish, but I intend to keep experimenting along these lines.  I was pleasantly surprised to see how much better/faster the oil soaked in.  I think I got significant end grain penetration of the oil.  I did sort of mess this test up a little by adding the thinner, and I suppose that I could try it again with straight danish oil that has been heated.

It will be interesting to see if heating the oil helps to speed the cure time, which is reportedly the other major benefit to this method of application in addition to the superior penetration.  I’ll report more later.

For $10, the crock pot seems full of interesting potential.  I might take a crack at mixing my own finishes; could be fun and interesting.  I also ordered some bees wax to test another idea I had.  I’ll try to post about that tomorrow.

 

– Jonathan White

About Jonathan

I am a woodworker and hand tool restorer / collector. I buy too many tools and don't build enough - I need help!
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9 Responses to Hot Danish Oil

  1. Interesting post as I suck at applying a finish. Make sure to post before and after pics.

  2. Mark Lauer says:

    I’ve had good luck doing this with BLO, Tung, and Coconut oil. I just microwave them for 30sec-1min and apply. An interesting, but more risky variation is to heat the piece you are working on in the oven at as low as it will go and then apply the oil finish. As the piece cools off it will draw oil into the pores and you can apply more. I did cause a check in a bowl doing that once however, but at a higher temperature. I actually heard it happen. One of these days I’ll make some test bars and apply things different ways: heat oil, heated wood, both, normal cold application, thinner, etc and cut through them to see the depth of penetration. In previous experience, it’s not far (~1/32″) for a normal application, so it would be interesting to see.

    Mark

    • Jonathan says:

      Hello Mark,

      I had never thought of heating the work piece. On smaller things that might be an interesting thing to try. I think that these vise chops are probably a little too big to put in the oven though. They might fit one at a time, but I don’t think that all four at once would work. My bigger concern would be the wife’s reaction to cooking danish oil in the house. When I refinished a bunch of stanley planes, I used a high temp ceramic paint and I baked it on in the oven. She wasn’t amused. The house stank for a day, oops!

      I think that the test bars are a fantastic idea. That’s one of those things that I think “One of these days, I’ll try”, but finding the time never seems to happen. I think that your 1/32″ estimate is probably correct for face grain, but on end grain I wouldn’t be surprised to see penetration over an inch deep.

      Thanks for chiming in with your thoughts. I appreciate it.

      All the best,

      Jonathan

      • Mark Lauer says:

        I actually cut into the end grain as well and the penetration wasn’t very deep there either (1/32-1/16″). I think this was in cherry, so fine pores and was only a single application left over night. I was very surprised by how little it was the whole way around.

  3. Jim Scheltens says:

    I’ve heated old oils that were probably way, way past their shelf life and applied them with good success. BTW, I also use my table saw as a primary assembly/glue-up table. But I hate getting stains on the cast iron surface. Years ago I made a 3/16 inch thick plywood cover for the table top that has a 3/8 inch lip to hold it in place on the saw. Retract the saw blade and drop the plywood on and slide it till the borders drop around the table top. I keep the top of the plywood varnished and waxed so glue drops just pops off. It is quick to take off when I want to use the saw, but gives me a dead flat work surface for 95% of the time.

    • Jonathan says:

      Hello Jim,

      That sounds like a great idea. Tempered hardboard might be a good choice too! My only concern would be storing the plywood/hardboard sheet when not in use. Not a major issue, but the pice would be about two feet deep by six feet wide. My shop isn’t big enough that I ever plan on building a dedicated assembly table, so this might be a very good option. I’ll certainly have to give this some thought. Thanks for commenting.

      All the best,

      Jonathan

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