Watco Danish Oil Question

[David Louie]

I have been using about 5-7 gallons of Watco Danish Oil stored in a plastic garbage can with a lid over the past 2 years. I soak pieces in it and then drip dry them and use paper towels to blot the excess. Recently, I have noticed that the oil has become reduced in volume, noticeably more thick and viscous, and takes longer to penetrate Norfolk Island Pine bowls. The oil still provides a good finish to my bowls. It is still liquid, just like a heavy motor oil now, rather than the thinner oil when fresh out of the can. Any suggestions on what I can do or should do? I thought that maybe the addition of mineral spirits might help. Should I just throw the whole batch out and start over? Any other things to add? Does the oil still penetrate and harden as well as new Watco Danish Oil? Thanks for the assistance.

 

[Ian Thorn]

I have thined small amounts with turps and it works for me but not sure about the voll you are using I sugest trying with a pint and see what happens then you dont loose the lot 😱 if it dose not work

Ian

 

[MichaelMouse]

I'll go with Ian on this. Wouldn't hurt to replace the volatile element in a test. If the oil is starting to polymerize - gel - already, you may not find it fully effective. One part in 5 would be a good place to start. Don't wipe the surface of your test piece, look for thick puddles on the surface after the solvent evaporates.

 

[Mark Mandell]

I have been using about 5-7 gallons of Watco Danish Oil stored in a plastic garbage can with a lid over the past 2 years. I soak pieces in it and then drip dry them and use paper towels to blot the excess. Recently, I have noticed that the oil has become reduced in volume, noticeably more thick and viscous, and takes longer to penetrate Norfolk Island Pine bowls. The oil still provides a good finish to my bowls. It is still liquid, just like a heavy motor oil now, rather than the thinner oil when fresh out of the can. Any suggestions on what I can do or should do? I thought that maybe the addition of mineral spirits might help. Should I just throw the whole batch out and start over? Any other things to add? Does the oil still penetrate and harden as well as new Watco Danish Oil? Thanks for the assistance.

I suggest you contact WATCO and ask the guys who make the stuff.

 

[gary rock]

David-

Have thined mine with mineral spirits.

Gary

 

[Darryl Fective]

I suggest you contact WATCO and ask the guys who make the stuff.

I'd bet dollars to donuts they'd choose selling him a few new gallons over suggestions on salvaging the old.

Scoop some out, thin it down and give it a try. I'd guess it will be just fine. That stuff can thicken up just in a quart can with a tight lid.

 

[Mark Mandell]

I'd bet dollars to donuts they'd choose selling him a few new gallons over suggestions on salvaging the old.

Scoop some out, thin it down and give it a try. I'd guess it will be just fine. That stuff can thicken up just in a quart can with a tight lid.

If it has started to polymerize, using a diluent like mineral spirits is more likely to result in a weakened film. Not hugely important unless handling and use of the item is likely, but still not a great idea.

I'm not clued into the benefit of soaking bowls in 7 gal. of Watco. The resulting finish won't be any stronger and the more the wood absorbs (suspect not all that much) the longer it will take to fully release the included solvents and proceed to a full cure of the oil.

 

[Bill Boehme]

I think that most, if not all of the Watco products contain linseed oil and some sort of varnish and varying amounts of mineral spirits depending on the particular product. If you are storing it in a pail with a lid that isn't providing an air tight seal, it sounds like in addition to the mineral spirits evaporating, the varnish and oil are probably over the hill. Depending on how much it is exposed to air there might be a potential of going high order (AKA, thermal runaway).

 

[Odie]

I think that most, if not all of the Watco products contain linseed oil and some sort of varnish and varying amounts of mineral spirits depending on the particular product. If you are storing it in a pail with a lid that isn't providing an air tight seal, it sounds like in addition to the mineral spirits evaporating, the varnish and oil are probably over the hill. Depending on how much it is exposed to air there might be a potential of going high order (AKA, thermal runaway).

I was thinking similarly to Bill, in that the plastic garbage can lid probably isn't making an air tight seal........leading to evaporation.

I've been using Watco Danish Oil for three decades, and I honestly don't think I've ever seen it thicken. I do, however, store it in the original containers, and probably use no more than a a few tablespoonfuls worth at a time.

As I was reading this thread, the thought occurred to me that you might want to try and find some industrial chemical resistant containers for your dipping operation. We use them where I work, but those all have bung holes. Some are metal, and some are chemical resistant plastic. I'd be willing to bet something like a 30 gallon plastic container with a wide mouth air tight lid is available somewhere, if you were determined to find it........😀

ooc

 

[Bill Boehme]

And ... in addition to all of the pitfalls mentioned above, the cumulative effect of repeated dunking and soaking is gradually contaminating the Watco. Like Odie, I have never had a problem with it going bad in the sealed can.

It would be helpful to clarify which particular Watco product is being used. I have used Watco stain for furniture and cabinetwork matching by blending colors. These are mainly a mixture of dye and pigment colors, mineral oil, and a small amount of varnish and linseed oil. Other products like Watco Teak Oil contain much more oil.

 

[David Louie]

Great comments!

Thanks to all of you who posted. I'll thin it with mineral spirits and let everyone know what happens. Come to think of it, I have periodically refreshed the mix by dumping in new Watco Danish Oil (Natural) can every now and then, but I haven't done so for about 9 months or so. The mix is getting thicker when I wipe off the coat, so it may be starting to gel. I'll see if that slows down when I add new mineral spirits. I tried to locate a plastic air tight barrel, but was unable to find one here in Honolulu, so I decided to make do with a trash can. I turn bowls on my Jet 1642 up to 15 inches inboard, and about 10 inches high, so I wanted something to dunk them in, especially the Norfolk Island Pine. Thanks again for the comments.

 

[Ian Thorn]

Just thinking on the air tight pail I home brew beer and spirits the container is fully air tight plastic if you can buy them there

Cheers Ian

 

[MichaelMouse]

Even if it is starting to gel a bit, you can still get use out of the gel by rubbing it in as finish on other pieces. It should stay behind in reasonable quantity when you decant the thinned liquid. Where the solvent won't disperse it to reduce viscosity, heat still will. Unfortunately, you can't use the heat in your tank, because it will also aid the chemical action producing the gel.

I was not aware that WATCO had 40% solids, though the MSDS is only obliged to report the solvents. That's more than wipe-on poly.

Should be able to get any solids like sawdust out by filtering through cloth, I would say.

 

[Ian Thorn]

You could try the first filtering though an old, used ladys stocking.ok now the jokes start

Cheers Ian

 

[MichaelMouse]

You could try the first filtering though an old, used ladys stocking.ok now the jokes start

Cheers Ian

Or as the three-year old called them. "Panty holes."

 

[john lucas]

I don't use Watco anymore but other similar finishes that I've used have just continued to go bad after it starts jelling. Thinning with mineral spirits or Naptha helped short term but it just kept jelling worse and worse until I tossed it. I'll bet the Watco will do the same.

 

[Mark Mandell]

I don't use Watco anymore but other similar finishes that I've used have just continued to go bad after it starts jelling. Thinning with mineral spirits or Naptha helped short term but it just kept jelling worse and worse until I tossed it. I'll bet the Watco will do the same.

Before I switched to waterbornes, I used to use oil poly on furniture as a topcoat. I thinned it with 20% Naptha as it was required for the HLVP spray and greatly enhanced hand application because it improved leveling and eliminated brush strokes while shortening the film's drying to dust-free.

There was, however, a drawback. Once I added the Naptha I could not return any unused mix to the can as it would jel the entire volume in less than 2 weeks. I actually called a finish chemist about it and he explained, in terms that I could understand, that the Naptha would act to accelerate the cure and the whole can would proceed to do what he called "autopolymerize". It would only jel because there wasn't enough oxygen in the can for a full cure. I ruined a whole gallon of oil poly to learn this lesson.

Lesson - When thinning with Naptha, use only as much as you need to finish the job at hand.