Danish Oil mishap and Advice

[Emiliano Achaval]

I just got back from Argentina. I did a demos and gave a lesson there. The AAW donated 14 tools to a school for handicapped kids learning life skills, they have 2 lathes and some home made scrapers, now they will be improving a lot with some real tools...
I took several Koa pieces as presents. I finished most of my turnings with Danish Oil. Some of the pieces ,I finished just a few days before the trip. They all looked great, no flaws. Imagine my surprise when at the hotel unpacking the bags, I see that the Danish Oil had somehow seeped out!! It looked like when you apply the oil, then you forget to wipe it clean after 15 minutes, and you come back the next day to find a mess...
I'm guessing the pressure in the cargo hold did that... Its about 20 hours of flying time from Maui to Buenos Aires... I sell a lot to tourists that stop by my shop, I wonder how many times that happened to them if what they bought was finished recently??
From now on, I will have to make sure that the Danish Oil had enough time to dry and hardened ... I had no idea that could happen. Nobody has ever complained, but its definitely possible that someone flew to NY with a Koa bowl with a fresh coat of oil.... I cringe thinking about it. Funny thing is, nobody noticed it but me, I had to explain to everyone the little lumps on the surface... Found a 3M pad and wipe it as best as I could, but you know how hard it is to clean it, best way I found is back on the lathe and more Danish Oil and 320 and higher sandpaper...
I will be doing a live remote demos for the first Latin American Woodturning simposium on Saturday Nov 27, one of their sponsors is the AAW and TWB...

 

[Jamie Straw]

Oh, man, what a shock! Falls into that "Ya learn somethin' every day" category.

 

[Bill Boehme]

Thanks for posting that, Emiliano. It's not something that is obvious, but yes it would be the low pressure. At a nominal 35,000 feet cruise altitude the atmospheric pressure is 7 inches of mercury in the unpressurized cargo bay. Assuming that in Hawaii you are pretty close to sea level where the pressure averages about 29.92 in -Hg which means this is equivalent to putting the pieces in a vacuum chamber and pulling a vacuum of 22.92 inches of mercury. Oh man, that sucks.

 

[Emiliano Achaval]

Thank you Bill! I knew the plane ride did it, wasn't sure how. Great easy explanation and analogy! I will explain this to my customers and tell them to pack if possible in their carry on. I'm guessing it takes a month for the Danish Oil to fully harden? I'm also guessing I'm probably not the first one that has come across this... lesson learned!!

 

[Mark Hepburn]

... Oh man, that sucks.

Will consider that "unintentional" pun, a little bit of lagniappe, Bill. LOL.

 

[odie]

I think the cargo bays of most commercial airliners are pressurized......some of the smaller commercial carriers, maybe not.

All of my bowls are finished with Danish Oil natural, and it's been quite a long time since I have seen this "seeping" problem. This may all depend on where you are, and the ambient climate. It's a lot cooler and less humid here in Montana. Most of my bowls cure for at least a week, before buffing.

 

[stu senator]

As a test you could finish a few scraps and put them in a vacuum jar (plastic pipe with caps and fittings).

Stu

 

[Dennis J Gooding]

Cabin pressure altitude for airliners is required to be 8000 feet max, and commonly is much lower. At 8000 feet, the pressure is about 4 psi lower than at sea level. However, much smaller pressure changes will draw the liquid finish out, it just takes longer.

 

[Leo Van Der Loo]

I also would expect the cargo bays to be pressurized some, animals are carried in there also right, the same with the temperature, though probably cooler than in the cabin, combine that with old “Danish oil” and it could well be the reason of the bleeding.
Koa has larger open grain pores maybe ??, I never turned it, but if so the oil in those pores might not be dried yet.

I read of someone having had problems with shipped turnings that were packed in bubble wrap, and it got stuck to the pieces, the wrap was blamed then, but maybe it was also bleeding of the finish that caused this to happen

 

[Zach LaPerriere]

Thanks for sharing, Emiliano. Sounds like a cool trip!

Out of curiosity, was this pure Danish Oil or the more standard Watco or other variety with additives? My impression and experience with pure Danish Oil is that it takes a fair bit longer to cure, but if there's bleed out, it's more forgiving to being wiped a day or two later.

Who is up for building a hypobaric chamber to test this out??

 

[Mark Hepburn]

 

[RichColvin]

I fly a lot (over 2 million miles with United). There is a pressure change.

I bought a pewter flask in London, & carried it in my carry-on bag. I opened & resealed the flask whilst aloft at 35-38,000 feet. When I looked at the flask later at home, the sides had been sucked in about ⅛" on each side. The flask is only about 4" x 4" x ¾" thick.

So, this isn't surprising. Emiliano, I recommend the turned items be put into a large ziplock bag. I do that with any liquid in my checked bags, & am often surprised by how many items leak. Those bags have saved me repeatedly.

Kind regards,
Rich

 

[Emiliano Achaval]

Thanks for sharing, Emiliano. Sounds like a cool trip!

Out of curiosity, was this pure Danish Oil or the more standard Watco or other variety with additives? My impression and experience with pure Danish Oil is that it takes a fair bit longer to cure, but if there's bleed out, it's more forgiving to being wiped a day or two later.

Who is up for building a hypobaric chamber to test this out??

I used Watch Danish Oil... For now! lol

 

[Bill Boehme]

I think the cargo bays of most commercial airliners are pressurized......some of the smaller commercial carriers, maybe not.

All of my bowls are finished with Danish Oil natural, and it's been quite a long time since I have seen this "seeping" problem. This may all depend on where you are, and the ambient climate. It's a lot cooler and less humid here in Montana. Most of my bowls cure for at least a week, before buffing.

You are correct, so at most, you would experience a decrease in pressure of about 8 inches of mercury if you took off from an airport on the coast. While that's much less than my original horror story, it still could be bad news for a fresh application of oil. I sometimes see weeping on ring porous wood even when there is just a small change in barometric pressure or a big change in temperature during the first few days. Watco Danish oil and Minwax Antique Oil both contain polyurethane varnish so they cure faster than pure oils which would need at least a month and maybe longer to cure. I personally allow three months cure time for pure tung and walnut oils.

Odie, the elevation of the "Zoo" is 3200' so the pressure differential between that and airliner cabin pressure would be about three and half inches of mercury.

Mark, I always believe in giving a bakers dozen. I had a high school physics teacher from Louisiana who believed in giving a little bit of lagniappe so he always put a couple extra questions on his exams.

 

[odie]

I used Watch Danish Oil... For now! lol

I am also using the Watco Danish Oil product.

Emiliano.......Out of curiosity, are you using more than one coating of Watco Danish Oil? Are you attempting to saturate the wood? I did do these things in the past, and did experience some overnight seepage back then. All I do now, is get the surface good and wet, but wipe it all dry to the touch within about a quarter hour....done. If there is any difference in appearance between one and multiple coats of WDO, it's so small a difference, that it's hardly worth the extra effort to do it.

It's interesting about the possibility of turnings being transported in the cargo hold of airplanes. I have a customer base that spans N,S,E, & W of the lower 48 states.......and since I nearly always ship by USPS priority mail, I'm sure many of my bowls have been in the cargo bays of commercial airliners. I've never once heard anyone comment about seeping of the finish.

ko

 

[Bill Boehme]

I just did some Googling since I wasn't familiar with pure Danish Oil and found that Tried & True sells a product called, "Pure Danish Oil" which is partially polymerized linseed oil which means that it will cure faster than BLO.

 

[hockenbery]

Thank you Bill! I knew the plane ride did it, wasn't sure how. Great easy explanation and analogy! I will explain this to my customers and tell them to pack if possible in their carry on. I'm guessing it takes a month for the Danish Oil to fully harden? I'm also guessing I'm probably not the first one that has come across this... lesson learned!!

I would think most of you customers would bring their new purchase home in their carry on which will be in the pressurized cabin.

 

[Zach LaPerriere]

I just did some Googling since I wasn't familiar with pure Danish Oil and found that Tried & True sells a product called, "Pure Danish Oil" which is partially polymerized linseed oil which means that it will cure faster than BLO.

I've used this for at least a dozen bowls and it's great stuff. Instructions (on Youtube) call for the lightest possible coat and lots of 'em. WAY faster tack-free than BLO. Depending on wood species and porosity, I've done between 3 and 12 light coats, a day or two apart. It dries overnight to touch, but I've always given it at least a couple months before sending a bowl on to a new owner. Mostly I use walnut oil, but I like the Danish Oil where increased hardness and water resistance are important. That said, I think synthetic finishes are harder but I've never tried a side-by-side test.

 

[Emiliano Achaval]

I am also using the Watco Danish Oil product.

Emiliano.......Out of curiosity, are you using more than one coating of Watco Danish Oil? Are you attempting to saturate the wood? I did do these things in the past, and did experience some overnight seepage back then. All I do now, is get the surface good and wet, but wipe it all dry to the touch within about a quarter hour....done. If there is any difference in appearance between one and multiple coats of WDO, it's so small a difference, that it's hardly worth the extra effort to do it.

It's interesting about the possibility of turnings being transported in the cargo hold of airplanes. I have a customer base that spans N,S,E, & W of the lower 48 states.......and since I nearly always ship by USPS priority mail, I'm sure many of my bowls have been in the cargo bays of commercial airliners. I've never once heard anyone comment about seeping of the finish.

ko

Glad you asked this... Yes, I try to do 3 coats, with the usual timeline. You are right, I see no difference, except that I was hoping for long term care, I mean I hope my bowls are going to be around for generations and I was giving them a hand...

 

[odie]

Glad you asked this... Yes, I try to do 3 coats, with the usual timeline. You are right, I see no difference, except that I was hoping for long term care, I mean I hope my bowls are going to be around for generations and I was giving them a hand...

Emiliano.......Only my opinion, but I think the first coat of WDO will do 95% of what 2-3 coats will do, and there isn't nearly the problems of over-saturation with multiple coats. We all hope our works will survive for generations to come, but it's really up to those who will, or won't take care of them after they leave our hands. Some will survive, and some won't......not everyone will be an "appreciator" like you, I, and the original purchaser will be. Our works will be in the hands of fate, at that point!

 

[odie]

Just an additional thought here........Watco Danish Oil hardens as it dries, and that being so, probably creates a barrier that additional coats may not be able to penetrate. If that is so, then additional coats may not soak in and dry in any timely manner, simply because there is nowhere for it to go. At that point, it may take extended periods of time for pockets of DO to fully dry/cure.......

 

[Bill Boehme]

Just an additional thought here........Watco Danish Oil hardens as it dries, and that being so, probably creates a barrier that additional coats may not be able to penetrate. If that is so, then additional coats may not soak in and dry in any timely manner, simply because there is nowhere for it to go. At that point, it may take extended periods of time for pockets of DO to fully dry/cure.......

Watco Danish Oil contains polyurethane varnish so I agree, it is just a thinned oil/varnish blend and after a couple applications, it will build to a glossier finish. When I want to build a slightly glossy finish, I like Minwax Antique Oil Finish.

 

[Raul McCai]

I'm guessing the pressure in the cargo hold did that... Its about 20 hours of flying time ...

And cold. It is quite cold in the hold. Squeezes things

 

[Raul McCai]

I'm guessing the pressure in the cargo hold did that... Its about 20 hours of flying time ...

And cold. It is quite cold in the hold. Squeezes things

 

[Gerald Lawrence]

I usually use 3 or more coats of Watco and when I bring it in can still smell the finish up to 2 weeks later. So from this I would say that it is not fully cured for at least one month. Now the possibility presents if oil was applied and the flight is within 3 days will almost certainly be some oil present.

 

[Emiliano Achaval]

Emiliano.......Only my opinion, but I think the first coat of WDO will do 95% of what 2-3 coats will do, and there isn't nearly the problems of over-saturation with multiple coats. We all hope our works will survive for generations to come, but it's really up to those who will, or won't take care of them after they leave our hands. Some will survive, and some won't......not everyone will be an "appreciator" like you, I, and the original purchaser will be. Our works will be in the hands of fate, at that point!

Odie, you are 100% right! Not sure why I kept doing 3 coats, lol.