Tung oil not drying on cocobola?

[Brujo]

Has anybody had difficulties using tung oil on cocobola?

My general finishing technique is to sand to 600, apply a thinned (with turpentine) coat of tung oil, let dry, steelwool, and repeat with thicker (less turpentine) coats of tung oil till I'm happy with the finish. It usually takes 4-10 coats to be happy with the finish depending on how porus the wood is. I apply coats of oil off the lathe.

I recently tried to do this on a cocobolo bowl. It looks great but is still tacky 3 weeks latter! This is probably due to the high oil content of the cocobola but I am not sure. I'm thinking of putting a 100watt bulb in a box to create a drying box.

Does anybody have experience with tung oil on cocobola or drying finishes in a heated chamber?

-Justin

 

[dkulze]

you got it in one.

Wipe down with mineral spirits to get rid of that tacky feeling. If you recoat, let sit for a while then wipe dry. Heat it up under that lightbulb and see if it helps at that point.

The other nice thing bout cocobola, though is that it is dense enough to just sand to a high grit and buff out as is.

Dietrich

 

[DMcIvor]

greasy cocobolo

Dietrich's suggestion is a good one for salvaging the situation. Cocobolo doesn't stand up to my approach of multiple coats of oil, for exactly the reason you have discovered. I restrain myself to a single coat of tung oil, then end up wiping the piece down a number of times over the next 24 hrs to remove excess oil.

In general I've had better luck with teak oil on cocobolo. It's probably not the teak oil per se, and who know if there is actually any teak oil in teak oil (probably not), but whatever drying agent the manufacturer puts in the mix.

Don

 

[Ed Koenig]

No oil needed!

Justin,
There is no reason for using tung oil or any other oil on cocobolo. The wood has plenty of its own.

I sand to 600 grit, rub with 0000 steel wool and buff. That's all you need. If you must use oil, wipe it on and wipe it off. Or use friction polish, lacquer or some poly product that actually hardens.

Ed

 

[Bill Boehme]

Teak oil is oil that you apply to teak -- not oil extracted from teak. It is actually a linseed oil blend. Teak only needs to be oiled if it is exposed to the elements. I don't believe there is any oil that will dry on cocobolo -- in a normal lifetime anyway.

Bill

 

[GeorgeH]

Although I typically leave cocobolo unfinished and polished with it's own natural oils, the amount of oil in cocobolo is so incredibly high that, if I'm going to use a finish, I wipe it down with lacquer thinner beforehand. I agree with wiping off the tung oil and allowing it to dry naturally. I wouldn't put it in a heated box. Even though the wood doesn't tend to swell, the additional heat may cause more oil to migrate to the surface of the wood, exacerbating your problem.

 

[Chris Wright]

know your pain...

I had the same problem with the exact same technique just a bit ago. Heating it didn't work with the multiple coats. I simply used turpentine to take off the excess tung oil, let it dry, resanded the high grits to smooth and buffed. A light coat of Briwax to shine it up a bit more and protect it and I called it done. Cocobolo is funny stuff that way.

 

[John Nicholas]

Wipe Down

Wipe down with mineral spirits to get rid of that tacky feeling.

I had a tacky Danish Oil Finish on a bowl and found a quick Naptha wipe fixed it right up. I had the Naptha out - makes a great wipe down before finishing, shows up any needed sanding or scratches, plus removing all dust from sanding.

John 🙂

 

[Gretch Flo]

Tacky Danish oil

I had a tacky Danish Oil Finish on a bowl and found a quick Naptha wipe fixed it right up. I had the Naptha out - makes a great wipe down before finishing, shows up any needed sanding or scratches, plus removing all dust from sanding.

John 🙂

Am currently working with the nice people at Klingspor where I got my General Finish Danish oil. They also gave me Gen Fin 800 # to call and have been talking to them as well who aree going to getr back to me.
Problem: Have used Danish for the last ?3-4 years without a problem. The last 6-7 months I have had a tackiness on the hopefully last coat on various woods-maple, cherry, russian olive, maple, red cedar. Thought it might be the summer humidity. Not now in my living room with the wood stove going. I opened a new gallon-same problem. I had used acetone on some, and wet resanded others wiping the d O off right awayto correct . A lot of fuss
Changes that may have a bearing:
I am doing alot of green turning , natural edge, altho alot of my wood is fairly dry-spalted, only sand to 600, later 800, rather than 1200, and wet sand with the danish oil before taking off the lathe (I think it minimizes splitting). (I add coats to bring up to the satin finish I like)
Klinspor is sending me (no charge) some Japanese dryer to add to the DO. Hope to get it next week. Will also talk again to GF people now that I am not working this next week. Anyone have any thoughts or similar experience with DO??? Somewhat frustrated 🙁 , Gretch

 

[dkulze]

All I can think of, Gretch, is that you're using more coats or not drying as long in between. Figure that tacky is cause by oil that hasn't fully polymerized, which should be from solvent still present, humidity/water, or the piece isn't staying warm enough for the oil to set. Final coat on a piece that feels dry may still seal in or soak up solvents that are slower to release now that most of the pores are filled, especially if wet sanded.

If you're applying on the lathe, you can burnish with a clean cloth until the piece is nice and warm/hot to speed the polymerization process. Otherwise, try putting the pieces in a very warm place, maybe building a drying box next to the wood stove to hold it's heat.

When desperate, I've gone so far as to warm a piece with my heat gun or the output from my dryer (empty, of course) then sand out any bubbles or lint and buff.

dietrich

 

[Gretch Flo]

Danish oil tackiness

All I can think of, Gretch, is that you're using more coats or not drying as long in between. Figure that tacky is cause by oil that hasn't fully polymerized, which should be from solvent still present, humidity/water, or the piece isn't staying warm enough for the oil to set. Final coat on a piece that feels dry may still seal in or soak up solvents that are slower to release now that most of the pores are filled, especially if wet sanded.

If you're applying on the lathe, you can burnish with a clean cloth until the piece is nice and warm/hot to speed the polymerization process. Otherwise, try putting the pieces in a very warm place, maybe building a drying box next to the wood stove to hold it's heat.



Thanks Dietrich- My house is near 70 most of the time but vacillates some-esp when I work and am gone for 11-12 hours. I think because I wet sand that it has a bearing.(didn't used to do that) Sometimes I wait several days before that last coat, tho, so why would it take so long to polymerize??? I add coats when it feels dry. Sometimes the next day. (cherry only takes about 2 coats, spalted maple 3+, and spalted soft maple more than that. I think beech takes 3-4. Maybe I should wait even when it sucks the stuff up rapidly.
Do you think the Japanese dryers that Klingspor is sending are going to help?? Would naptha as suggested by others to take the tackiness oof would dull the finish? Gretch

 

[Old Bolivian]

oily exotics

I have lots of Bolivian Morado which also doesn't take oil finishes.... except...
Teak oil does seem to work. I made a curio cabinet for my wife out of the morado and it did take teak oil. I have read that non wax shellac will work and I'll try that the next time.

 

[dkulze]

Unfortunately, the speed at which it sucks it up is more indicative of longer drying time than shorter. The more oil there, the longer it will take for the solvent to evaporate and the oil to polymerize. With the wet sanding, you're sealing in solvent by heating the surface and mixing the oil with sanding dust, so several days might not be enough for it to outgas. A few weeks might be a better bet.

My personal experience with tacky finishes has had less to do with the solvent than the polymerization. I'm wondering if building coats affects the ability to polymerize. I know that temperature, humidity, and the presence of natural and nonpolymerizing oils can. I'd imagine that a heat lamp would solve the problem pretty quick and I suspect that an UV lamp would cause rapid curing, as sunshine does even when it's cool out.

Good luck,
Dietrich

 

[Gretch Flo]

Unfortunately, the speed at which it sucks it up is more indicative of longer drying time than shorter. The more oil there, the longer it will take for the solvent to evaporate and the oil to polymerize. With the wet sanding, you're sealing in solvent by heating the surface and mixing the oil with sanding dust, so several days might not be enough for it to outgas. A few weeks might be a better bet.


The perplexing thing is that this didn't used to be the problem with the coats previously, using the same jug (I pour 2-3 oz in a small bottle for daily use), and then opening a new gallon (same results). The wet sanding is the new variable. When I wet sand it is at a slow speed, and I can't feel heat. Maybe I'll have to just try waiting for the second coat, but I don't want to take forever!!! Haven't received the Jap dryers yet from Klingspors.
Gretch

 

[dkulze]

Ya know, I know that shellac can lose it's ability to harden well with time. I wonder if you can get a similar problem with the eurythane finishes. I wouldn't tend to think so since they're working from a completely different chemical process but ya never knows.

I'm guessing that it really is the wet sanding. The whole purpose of doing that is to seal up the pieces pores with the sanding dust/oil mix. Seems like it's working a bit too well for ya there. Have you considered simply dropping that step or does it give a sufficiently improved finish to make it worth the bother?

Try heat. Hook up your outflow from your dryer to a big-arsed cardboard box and run it on delicates for a hour with the piece inside the box. Oh, and make sure and put a pair of panty hose over the end so your piece doesn't end up with 5o'clock shadow. If the delicates setting doesn't heat up enough, give it a shot at full heat. This may be all it takes.

dietrich