Finishing Oily Woods

This article was inspired by a question from Schuyler. He writes:

I put two coats of General Finishes Seal-a-Cell on a piece of cocobolo, then a coat of Arm-r-Seal Urethane top coat (gloss). Three days later, it?s still slightly tacky. Will this ever cure enough that I can continue applying coats of Arm-r-Seal? What gives?

What a Mess!

Many exotic species, like cocobolo, have a certain amount of natural-occurring oils in them. When you coat them with an oil-based finish, the oil in the wood itself prevents the finish from curing properly. The end result is typically a gooey sticky mess.

Prevention

Fortunately, we do have options. First, you can use an evaporative finish, such as shellac or lacquer. These finishes don’t cure via oxidation and will usually have no problem curing on an oily wood. A second option would be to seal the natural oils in using something like dewaxed shellac. A 1-2 lb cut should do the trick. Start by freshly sanding the surface and remove the excess oil by wiping the surface down with either acetone, lacquer thinner, or denatured alcohol. Immediately follow up by wiping or brushing a light coat of shellac onto the surface. Once dry, sand lightly with 320, vacuum the dust, and proceed with your oil-based top coats.

Now keep in mind, its probably best at this stage to stick with straight varnish and avoid oil/varnish blends such as Danish Oil. An oil/varnish blend works best when it can absorb deeply into the grain, and the shellac sealer coat prevents this from happening. So if you insist on using a blend, be sure to apply very thin coats and wipe off all the excess. Or play it safe and just use a straight varnish that contains no raw oil.

How to Fix It

Now if you are in a situation like Schuyler here, and you have a sticky mess on your hands, here’s what I recommend. The first thing you can do is simply wait. In most cases, the finish will eventually cure. It can take weeks or even months, but it should get there. For most folks, this is not a reasonable time-frame. So another option would be to rub the surface down with some steel wool and mineral spirits. Buff the surface rather aggressively as you attempt to remove some of the uncured finish. Let this dry overnight and see if the tackiness is still present. If it feels fairly dry to the touch, give it a light coat of shellac as described above. If its still tacky, move on to option three: the do-over! Sometimes, the best course of action is to scrape or strip the old finish off, and start over again. It’s not my favorite solution, but sometimes you just have to do it.

Have you had experience with oily woods? How did you handle it?

Category: Finishing

Comments

  1. Steve Carter April 7, 2008

    I just ordered an excellent DVD that covers exactly this situation!

    Some guy named Marc something-or-another shows how to seal woods like oily cocobolo with shellac and then apply a wiping varnish to finish the piece.

    The DVD is called A Simple Varnish Finish Check it out.

  2. Just a word of caution in regards to working with Cocobolo, apparently this is one of the most toxic woods. Care must be taken when cutting and sanding this wood because its oils can cause allergic reactions if inhaled or exposed to unprotected skin and eyes.

    They say that there are two kinds of people in the world – those that are allergic to Cocobolo and those that don’t know it yet. :)

  3. Bob A in NJ April 7, 2008

    I learned the hard way about cocobolo. The first bowl I got away without an itch, the 2nd one caused a rash on my face and arms. A few days later, I got a poison ivy like rash betweem my fingers which lasted several weeks. Be careful with this wood. I’ve learned that other woods can also be toxix or cause allergies, including cherry and walnut. My advise, research all types of wood before you buy a lot of it.

  4. TwoHerbs (http://) April 8, 2008

    Concerning the allergic reactions, I spent almost all day one New Year’s day in the hospital with folks flooding my eyes because of dust from cocobolo and padauk (padauk is “supposed to be” non-toxic and allergenic but….). Thus the warnings should be taken seriously.
    I finished a cocobolo box with an oil/varnish finish probably 15 years,and never had a problem…maybe luck, but have done it since and never had a problem either. Go Figure!

  5. Bruce Croskey April 8, 2008

    On Cocobolo I find that buffing the wood with tripoli and then possibly a wax finsih is best.
    bc

  6. Darryl April 8, 2008

    Just wondering if the initial question was more like, “CAN I … finish Cococbolo with oil, and if so how do I go about it ” ??? thanks,dkd

  7. James Oliver April 11, 2008

    I just finished a cocobolo and pink mirado chess table for my son. Since it isn’t a heavy use table it doesn’t need a heavy use finish. Three coats of pure Tung oil with 48 hours between applications (no polymerization issues encountered) followed by four applications (24 hours apart) of Briwax Antique Mahogony power buffed between applications. This gives a very satin “touch me” surface.

  8. Kevin May 19, 2008

    I’ve been working on a Cocobolo peppermill to give as a gift. I used Miniwax 209 on the outside, and after reading various posts throughout the internet, I am at a loss as to what to use on the inside of the peppermill.

    Does anyone have any suggestions on what I can do to seal the inside so that the peppercorn is not contaminated?

  9.  

    Hey Kevin. A couple coats of shellac would be my suggestion.

    • Jason November 17, 2009

      Why is it better use sealcoat rather than just bullseye clear shellac. I’m fixing to start finishing a little project myself. I’m planning on having maple splines as well. Will the oils in the Cocobolo bleed into the maple? Thanks -J

      •  
        thewoodwhisperer November 17, 2009

        Well it isn’t necessarily better. But since I rarely use shellac as a topcoat and I usually just use it as a sealer, I always default to using SealCoat. So in this case, regular bullseye shellac would work just fine.
        And with your maple splines, I think you’ll be ok.

        • Jason November 17, 2009

          Thanks I had planned to use Shellac as a basecoat and then laquer over the top. I guess maybe the sealer would better for this. I should have been more clear. The box is going to be a small recipe card box. I’m not sure if I want to use a satin or gloss finish. Any suggestions on finish type and or a brand that works well. Thanks -J

        •  
          thewoodwhisperer November 17, 2009

          Well honestly, anything will work. I know it might sound daunting when there are so many options, but anything from shellac, to poly to lacquer will do the trick. Maybe take the opportunity to try a finish you haven’t worked with before.

  10. Paul Holland April 6, 2010

    I am making a dining room table top out of hickory with Brazilian Cherry for an outside border it will have an inlay in a diamond shape in the center of cocobolo. do you have any suggestions on how to finish the top?

    •  
      thewoodwhisperer April 6, 2010

      Hey Paul. I would probably suggest a varnish or a pre-cat lacquer if you have the means to spray. You need something durable on there and those would be two decent choices.

  11. Hello-

    I getting ready to finish a piece of cocobola that will be outside from time to time; I read what you said about Epifane clear coat varnish, so, I was going to use shellac sealcoat, 50/50 epifane, 75/25 epifane, 80/90 epifane.

    What do you think?

    Thanks,
    Darren

  12. TimV March 28, 2011

    I’ve only turned a set of salt/peppermill out of cocobolo. What a beautify turning that comes out of this wood. I wiped the piece down with acetone then wiped on a layer of thin CA glue with the lathe at slow speed. The CA glue cures hard and I was able to buff it to a high gloss. I don’t know if that would be appropriate on a piece of furniture.
    Tim

  13. I’ve always read/been told that rosewood and cocobolo contain a natural wax (as opposed to oil) in their pores. When working with these woods on guitars, the usual suggestion is to wipe them down with acetone on a rag until they stop giving off color on the rag. This removes the wax and allows the subsequent finish to dry properly. I’ve always followed the acetone treatment with a sealing coat of shellac and never had a problem when the topcoat is varnish.
    Cocobolo when used on small items will take a pretty nice polish if buffed on a rag wheel with buffing compound. It polishes like plastic and can be finished off with a coat of paste wax.

    DD

    • Will September 2, 2012

      Have you ever heard of someone polishing cocobolo on a guitar back and sides? Any reason you can think of that this won’t work?

      thanks

  14. I’ve turned a couple of bowls with cocobolo as well as a number of pens and tool handles. I’ve used friction polish and wax on them and haven’t had any problems. I have done one larger piece, though not real big, (not on the lathe) and when I finished sanding it I wiped it down with denatured alcohol, let that dry and applied a water-based sanding sealer and then finished with wipe-on polyurethane. It’s been a couple years and I haven’t seen any problems with the finish.
    I thought I was allergic to cocobolo for a long time because I had gone to a woodworking supply store twice and both times broke out in hives that night. The only thing I could think of that might have caused it was handling some pen and turning blanks, some cocobolo. Then someone sent me a piece as a freebie with some pen blanks I bought through Ebay and I had already handled it by the time I found out what it was…no reaction. Since then I’ve worked with it many times with no problems. I still don’t know what caused the hives those two times, but I haven’t been back to that store again either.

  15. Barry Lam May 1, 2011

    Mark, do you have any thoughts on using a salad bowl finish over a coat of shellac that seals an oily hardwood tabletop? I have a friend who just purchased a dining table made of reclaimed wood from Indian railroad tracks, a very oily dense hardwood a little bit like an Indian rosewood table I bought a few years ago. The top is unfinished, and she asked for suggestions on keeping out stains from spills or glass-marks without spoiling the natural look of the unfinished wood. I thought about salad bowl finish from your previous project. I didn’t know how the finish would work on the wood alone, so I thought a sealing coat of shellac first. Any thoughts?

    •  

      If you are talking about something like General Finishes Salad Bowl Finish, then yes that would work just fine. That’s because their salad bowl finish is just varnish, and should have no problem drying over a shellac-sealed surface. So a good coat or two of dewaxed shellac should seal the wood adequately in preparation for your topcoats of varnish.

  16. charlie May 5, 2011

    JUST NOW TURNING OUT A BIG SALAD BOWL FROM COCOBOLO AND PLANNING TO FINISH WITH OLIVE OIL. IS THERE ANY DANGER FROM THE COCOBOLO OIL CONTAMINTION?

    •  

      Hey Charlie. You’ll find differing opinions on this stuff but here’s mine. Any wood that has a high natural oil content is not the idea wood for a food-related item. But on something like a bowl, you can sometimes get away with it by putting a film finish on the bowl and sealing in the natural oils. So dewaxed shellac comes to mind as a good sealer. And generally speaking, olive oil should not be used on any wood food item because it can go rancid. Again, different opinions on this since lots of folks still use olive oil. But rest assured it can and will go rancid. Whether or not you notice it is a different story. So if you want a safe non-drying oil for your bowl, try mineral oil. But for me personally, I wouldn’t want to use an oil alone on a bowl made from a naturally oily wood.

  17. Murray D January 15, 2012

    I recently did a project that had a carved Paduk insert into white pine. When it came time for finishing I was going to seal the woods with shellac then spray a topcoat of water based lacquer. Well when I applied the shellac the orange-red resins from the Paduk bled in the white pine. You could see it from across the room.
    After some research and talking to other woodworkers I came up with this technique. First I wanted to preserve the orange-red of the Paduk, which fades over time. To try to slow that down I mixed up an orange-red Aniline wood stain and stained the Paduk. I followed that with coating the whole project with a water based sanding sealer and finished off with 3 coats of a water based lacquer. Using water based finishes did not dissolve the resins/wax of the Paduk and as such minimized the contamination.

  18. Jay L April 10, 2012

    Marc, I recently did some turnings made with cocobolo and I sprayed them with 3-4 coats of bullseye dewaxed shellac, thinking it would seal in the oils. I know the shellac dries very fast but I waited 24 hours before top coating it with only one light coat of Deft polyurethane from aerosol can, 3 days later, and it’s a sticky mess! I figured the shellac would have prevented this. Do you know if maybe the rattle cans use more solvents in them than brush on versions? Do you think the acetone in the poly dissolved the shellac just enough for the cocobolo oils to prevent curing? I use lots of exotic oily woods and don’t want to have this happen again. Is brush on method better than aerosol? I have my turnings back down to bare wood again, please help!

    •  

      That is a little surprising. Usually a few coats of shellac will do the trick. Brushing may help as it will put down a thicker barrier coat and rattle cans do lay down a very light coat. So maybe try five coats next time. If you have some scrap, it’s probably not a bad idea to use that for testing until you get the right regimen. And I really don’t think the poly did anything to the shellac layer, chemically speaking.

      Also, just before coating with shellac, I would recommend taking a rag soaked in alcohol and giving the ornaments a quick wipe-down. That will reduce the amount of oil on the surface. not sure how much it will impact your final results but it can’t hurt. Hope that helps.

  19. Joy S September 17, 2013

    Hate to quote wikipedia at people, but the entry there points out that “Cocobolo is yielded by two to four closely related species of the genus Dalbergia.” So the allergenic properties (or even the exact composition of the oil) actually could vary from species to species. (Also now endangered in several of its locations, which may mean people have moved from predominantly using one species to another, over time).

  20. Will shellac stop an IPE wood floor from bleeding after it has been painted?

Leave a reply

XHTML: You can use these tags: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

TWWGiveawayNov
bellforest200x200-tww10
EagleAmerica
Image Map
woodwhisperer-200x200-november
Advertisement