by Eric Meier

Conventional wood glues like Titebond are water-based, and they rely on penetrating into the grain of the wood, and then (once the water has evaporated) hardening, leaving a bond that is in many instances stronger than the wood itself.

The Problem:

Many tropical hardwoods are so oily or resinous that they’re practically waterproof. It would then stand to reason that if conventional wood glues need to penetrate into the wood in order to obtain a strong bond, then these oily woods would present a challenge in gluing.

Water beads up on the surface of Cocobolo.

Water beads up on the surface of Cocobolo.

Above you can see a picture of untreated, raw Cocobolo, which was misted with a spray bottle full of regular water. It should be plain to see that this wood, (along with a handful of other tropical species), appear to be nearly waterproof.

They’re technically not waterproof: since all wood, (even the Cocobolo pictured above), contains some degree of moisture that changes depending upon the relative humidity of the surrounding air. But for most intents and purposes, in the short amount of time that is elapsed in the gluing process, so little of the glue sinks down into the wood grain that it is essentially waterproof, or perhaps more accurately, glueproof.

Between different types of wood, and even within the same species of wood, there can be a lot of variability in oil/resin content, and gluing success/difficulty. Sometimes an oily wood can be glued with regular yellow glue with no problems, and in the next instance, the glue joint will almost fall apart on its own.

It would be preferable if the objects which we are building would stay in one piece!

So what can be done about this unpredictable nature of wood?

Some Solutions:

Please note that these are some solutions that can help give consistent results in gluing troublesome woods; but it is by no means a cure-all that is guaranteed to work every time, with all wood species and with all types of wood joints. On the whole, employing these tips should result in generally stronger, longer-lasting glue joints in oily woods..

1.) Wipe the wood surface with a solvent prior to gluing.

Since the primary problem that tropical woods present in gluing is their oiliness, (with density probably being the second biggest problem), any of these natural oils and resins that you can remove from the wood surface will help the glue adhere that much better.

While it’s not a cure-all, wiping the wood with a solvent first goes a long way. But you have to be sure of two things: first, you should try to glue the pieces of wood to be joined as soon as possible after the solvent has evaporated from the wood surface. This is because the wood’s oils will tend to migrate back to the surface of the wood where you removed some of the oils. Secondly, you have to be sure that the solvent you’re using is actually dissolving and removing the wood’s oils. A good way to gauge this is by checking the towel that you’re using to wipe the solvent to see if it’s changed to the wood’s color.

A solvent should lift surface oils from the wood.

A solvent should lift surface oils from the wood.

Note in the example above, mineral spirits was used to lift some of Cocobolo’s oils off the wood surface: and you can clearly see the stained orange cloth as evidence. If you’re initially testing a solvent, make sure that the wood is clear of any small particles of sawdust that might make it appear as though the towel is being discolored. Try a cloth with water first as a baseline: it should basically stay white since the water does not dissolve the wood’s heartwood extractives. Some common solvents that you can try are: acetone, denatured alcohol, lacquer thinner, mineral spirits, and naphtha.

2.) Sand the wood to help open up the grain.

You’ll notice that sometimes on particularly dense woods, just after they’re out of the planer, that they almost have a shine to them. This is because the blades of a jointer/planer can actually burnish the wood as it passes through the machine. Sanding helps to break up this flattened/polished surface so more glue can penetrate into the wood. It’s tempting to take the wood straight from the planer or jointer and glue it immediately, but for stronger joints, especially in dense woods, it helps to sand the wood with medium-grit sandpaper before it’s glued.

3.) Use synthetic, non-water-based glues.

Since water is repelled by the wood’s oils, using water-based glues like Titebond® can pose problems—though Titebond® II or III are usually better at gluing oily woods than Titebond® Original. Instead, use glues that aren’t water based, and/or glues that can bond a wider variety of materials like plastics and other non-porous surfaces (since that’s practically what we’re doing with these exotic woods anyways).

Some examples of such adhesives would be: polyurethane glues (i.e. Gorilla Glue®, etc.), 2-part epoxies (i.e. West System®, System Three®, etc.) and, if the parts to be glued are fairly small, cyanoacrylate glues (i.e. “super” glue, Hot Stuff®, etc.).Also, if using a polyurethane-based glue, it’s important to wet the wood surface with water just before gluing. Polyurethane is activated by moisture, and it may not receive enough moisture to cure properly if the wood has been kiln-dried and is very low in moisture content.

 

A List of Troublesome Woods:

Wood Gluing Notes
Bubinga High density, closed pores, and natural oils can cause problems with glue penetration.
Bulletwood High density and moderately oily.
Cocobolo Very high oil content and high density.
Cumaru High oil content and high density.
East Indian Rosewood High oil content and medium/high density.
Ebonies Some oil present, along with very high densities.
Ekki High density and moderately oily.
Goncalo Alves High density and natural oils prevent water absorption.
Greenheart High density and natural oils.
Honduran Rosewood High oil content and high density.
Ipe Reportedly very difficult to glue in exterior applications, especially for the long term.
Katalox Very high density, along with natural oils.
Kingwood Very high oil content and high density.
Lignum Vitae Extremely high oil content and density can pose gluing challenges.
Osage Orange Oils present can give gluing problems.
Purpleheart High oil content and high density.
Rosewoods Typically very oily and very dense.
Santos Mahogany High density and moderately oily.
Teak Oils/resins can present challenges in outdoor applications.
Verawood Extremely high oil content and density can pose gluing challenges.

See also:


Are you an aspiring wood nerd?

The poster, Worldwide Woods, Ranked by Hardness, should be required reading for anyone enrolled in the school of wood nerdery. I have amassed over 500 wood species on a single poster, arranged into eight major geographic regions, with each wood sorted and ranked according to its Janka hardness. Each wood has been meticulously documented and photographed, listed with its Janka hardness value (in lbf) and geographic and global hardness rankings. Consider this: the venerable Red Oak (Quercus rubra) sits at only #33 in North America and #278 worldwide for hardness! Aspiring wood nerds be advised: your syllabus may be calling for Worldwide Woods as part of your next assignment!

38 Comments

  1. Bruce Gardella May 26, 2018 at 12:17 pm - Reply

    Can anyone recommend a glue that will work on Milo wood joints?

  2. Joel van Lennep May 6, 2018 at 2:38 pm - Reply

    Have you (pl.) ever noticed that when you use masking tape (etc.) on a smoothed but unfinished tropical hardwood (like cocobolo or Braz. r’w’d), when you remove it, it leaves the area to which it was applied, paler and slightly depleted of color (some of which comes off on the tape)? Well, I’ve found it helps in gluing, because, I think, it draws out waterproof resins. I prepare the surfaces to be glued and cover them with masking tape (lately, I’ve had good results with transparent packing tape, warming it, just slightly, with a heat gun, and pressing it down firmly under clamping). In a couple/three days (not more – if the tape leaves a residue, you’ve made the situation worse), remove the tape and glue up the joint. Do not do *anything* else to the surfaces: scraping, sanding, solvents, even touching them at all will just draw oils and resins back to the surface. Just coat both gluing areas thoroughly with your water-based glue (I use the lightly-tinted Titebond III) and clamp for longer than you would normally consider necessary – like overnight or longer (I think it helps). Remember, truly deep penetration doesn’t occur with dense, very resinous woods – only the actual microns-thick surfaces are involved, believe me (think about it for a minute). (If anything goes wrong, it’s automatically not my fault, btw.)

  3. Bill Abbott April 8, 2018 at 7:07 pm - Reply

    In his book, “Classic Guitar Making” (Copyright 1974, published by Lawrence A. Brock), Arthur E. Overholtzer writes about removing pitch and tar from Brazilian Rosewood. After sawing to size. He used “Spic and Span” laundry detergent and water, completely immersing the boards. He agitated through the day and changed the detergent solution daily, for a week, then boiled in clean water, with 3 changes. He taped the ends of the boards to slow evaporation from the end grain, and let them dry for a week. Titebond water-based glue worked fine on rosewood treated this way.

    One of his students, Rose-Ellen Leonard, used 5 changes of acetone, 2 gallons at a time, over multiple days, to the same end.

    Overholtzer makes a case for gluing only unstressed pieces of wood when building a guitar. He would boil the wood for the sides and then clamp it to a cast aluminum inside-shape-form with heated clamping pieces. Similar to how wood was once steamed to make ship and boat hulls, and furniture. His success criteria for pitch and tar removal was whether the boiling and hot-clamp bending would cause hydrocarbons to come to the surface of the wood. He reported none present after his detergent and water soak, and Leonard reports the same for her acetone soak.

    Living in semi-rural Chino, California, with high warm-weather temperatures, and low humidity, clearly facilitates this kind of treatment. As does working with thin pieces. I haven’t worked with oily woods myself. Overholtzer’s book is as much of its time as the original “How To Keep Your Air-cooled VW Alive” and recommended for the same strengths, and weaknesses.

  4. Sed October 14, 2016 at 12:27 pm - Reply

    Has anybody ever had problems gluing yellowheart wood? Does it have a high oil content like purple heart or cocobolo?

    • Alan G March 26, 2018 at 10:45 pm - Reply

      I have recently glued yellow heart and purple heart for a segmented turned bowl. I had no problems and I used Titebond original.

  5. Bill Kutz June 11, 2016 at 11:20 pm - Reply

    I am somewhat new to woodworking, as I was a tool & die maker for 41 years. I know that the super glues have a tendency to break down in about 5 to 7 years, but I am wondering about the type that uses an Ultraviolet light to activate it. I have had great success using it to repair ceramics, some wood, and plastic. I have even glued Teflon on cast iron. Since Teflon is so slick, it really presents an economic issue to bond it to anything. I also have used it to bond an old wood plane base and a thin piece of UHMW, and so far it is staying. Perhaps the cost of this type of adhesive would limit it’s use in a large scale operation, but it seems to really work. Has anyone had any experience using it for a long term use? I know you can buy some pretty strong UV light for industrial use, and you have to be careful not to burn yourself with them. They can fry your skin in little time.
    Great site! Really helps beginners and craftsman alike.

  6. Spencer November 6, 2014 at 7:48 pm - Reply

    What wood would be best if I wanted to glue two woods together

  7. ejmeier July 10, 2014 at 10:57 am - Reply

    Not having actually seen knitting needles, it’s hard to visualize what is being done. In the end, it will come down to how clean the fit is between the two mating parts. If it’s a clean fit, I would just use CA glue (aka “super” glue). If the fit is sloppy or loose, your chances of long term success are much lower, but you could try a two-part epoxy to take advantage of it’s gap-filling properties.

  8. Steve May 26, 2014 at 3:28 pm - Reply

    I haven’t used the G/Flex yet that was recommended by Wood Sculptor, but I have used Smiths Oak and teak Epoxy, which worked fine and without any use of solvents too. It also remained flexible and had a discrete glue line.
    He is utterly on the pin with Cyanoacrylate, it wasn’t designed for this, and will fail normally sooner rather than later. Temporary repairs ONLY, brittle, and degrades under all sorts of conditions.

  9. Wood Sculptor September 28, 2013 at 1:36 pm - Reply

    For all these oily woods use either G-2 (System Three Epoxy) or G/Flex (West System Epoxy). These adhesives are specifically made for these woods. I prefer the “repair viscosity” G/Flex as it helps hold the joints together where clamping is difficult.
    Never use cyanoacrylate adhesives (CA or superglues) except as a temporary bond – they always fail after a few years. The G-2 and G/Flex adhesives remain flexible whereas CA becomes brittle so as the different woods move differently over time/temperature/humidity only the flexible adhesives can hold the oily woods together.
    Titebond Original works sometimes but the Titebond II and III are exterior woods and tend to expand over time creating a raised glue joint.

  10. Jim MacMahon August 5, 2013 at 8:21 am - Reply

    Many thanks. I’ll give it a try.

  11. Carter Ruff August 5, 2013 at 6:36 am - Reply

    I use the nonflammable formulation of Zip-Strip. It’s readily available in hardware stores where I live, and I think it’s widely distributed.

    I brush it on with a throwaway acid brush, give it a few minutes, scrape it off with a razor and clean up with water. If I’m in a hurry I’ll even use a blow drier to dry things off before gluing.

    Cheers!

  12. Jim MacMahon August 4, 2013 at 2:41 pm - Reply

    Hello, Carter, thanks for the suggestion. However, could you suggest a brand of paint remover to try as there a lot of formulations out there? I’m definitely interested. Jim

  13. Carter Ruff July 30, 2013 at 1:39 pm - Reply

    I am a guitarmaker, and have used cocobolo on a number of guitars, both as back and side sets, and as fingerboards and bridges. I’ve never had trouble with gluing it, and have used PVA, hot hide glue, and “all-wood” epoxy, all with good success. I have heard a warning about pre-treating with solvents, namely that it can cause more oil to rise to the surface from within the wood, and so I have chosen not to use that method.

    What I do is I pre-treat the glue joints with a chemical paint stripper before proceeding. I figure it’s designed to break down and remove resins and oils without penetrating too deeply, and leave behind a surface that’s ready to adhere to fresh finish or glue.

    I’ve done this quite a few times, and it’s never failed me yet. I hope this helps folks looking for a solution!

  14. enrique July 11, 2013 at 6:27 pm - Reply

    hi

    i am a guitar maker,,i use lignum vitae very ofter, it is a very very difiicult “customer” to glue, but since 3 months i started glue this one with cianocrylate, many times fretboards.

    i designed a big truss rod option specially for having less surface to glue, just 15mm sectors on the borders operation takes 15 minutes, and 6 grames of cianocrylate, it glues it mint, putting a good quantity of glue because it dries so fast that if bit glue, no time for pressing, but leaving a good hand of cianocrylate,,i press fretboard exactly 10 minutes and after that it is virtually impossible remove without cutting with a band saw.

    i detected values of this glue, that for example in case of need some like fretting, it provocates a lot of vibration, but cianocrylate it is absolutelly strong to any vibrations, do not expand,,and it is extremelly resistant to temperatures changes, also using cianocrylate same lignum vitae setting necks, it takes 30 seconds,and makes an unbreakable joint, before experiences show me that normal white wood glue must be avoid for gluing any super-oiled wood,,because there is no absorbtion into this woods and after or before the joints starts to open or the glue starts to “grow” on the joints this effect sometimes appears 2 or 3 months after, and reason it is not secure way.

    thanks a lot

    • zzzzz October 3, 2016 at 9:12 am - Reply

      if you are still around, can you tell me if the super glue held up. I was under the understanding that that glue is not good for a long time.
      thanks

      • Juggernaut1969 December 8, 2017 at 5:10 pm - Reply

        I cannot speak for the poster, but I can speak from experience.
        I have had no bad luck with inlays that were small and held in with superglue like glues. However larger parts exposed to prolonged stress often do fail. It can make a real mess of a fretboard, as the surfaces will separate, but enough of the superglue will remain in the wood making it difficult for a different glue to grab in a repair.

        • zzzzz December 12, 2017 at 12:47 pm - Reply

          good to know, thanks

  15. Etelon Longbows July 11, 2013 at 4:16 pm - Reply

    The glue sounds like urea formalderhide, such as cascermite, a powdered wood glue. I think the only thing that may dissolve it is water, as some manufacturers recommend that the glue lines are protected if using out doors

    There is A bowyer who has had similar problems with oily woods when using this glue and manage to repair them.

    If the pieces have not comletely seperated and there is only a thin crack then use CA, low viscosity (super glue)

    If you wish to seperate the parts then steam may work.

    A red colourd resin I use called resorcinol (Phenol formalderhide)Cascophen, would work very well, but is not always available.

    • Oscar Mayer July 28, 2017 at 6:03 pm - Reply

      You can order it online.

  16. Jim MacMahon July 9, 2013 at 3:34 pm - Reply

    I am trying to re-glue a Dansk rosewood bowl that has separated along several glue lines. The old unknown type of glue is white-ish and brittle and I have tried many solvents to remove it from the joints, but none has worked. I’d love it if someone could suggest a solvent to remove the old glue and also suggest an appropriate product for the repair glue up.

  17. Etelon Longbows May 9, 2013 at 11:13 am - Reply

    I glue up Ipe on a regular basis it is a very oily wood. I use Resorcinol resin as it is one of the only one that works well with oily woods.

    I used to Remove as much oil as possible using acetone but withe some pieces it would take forever and in some case end up more oily than after sanding. Even so resorcinol worked very well.

    Now sand the suface using 40 or 60 grit with a new belt where the grit is sharp.

    put a drop of water on a wast part to make sure it does not bead.

    I Use a wire brush to remove debris from the grain. This is espeialy improtant on Greenheart.

    apply a thin layer of resin then scrape it back into the contaner to remove any remaining dust then apply a thick layer of resin to both halves.

    Put both haves together but do not apply full clamping pressure for 45 minuits, thi allows the resin to soak in befor it is sqeezed out by clamping.

    With Greenheart in particular I would use this method.

  18. curly pio April 18, 2013 at 8:07 pm - Reply

    p.s. THE WOOD DATABASE is GREAT!

  19. curly pio April 18, 2013 at 8:07 pm - Reply

    I use it on knife scales and handles.
    The joint is basically Gorilla glue and the two wood pieces clamped until dry.
    I have had to router out a line joining both pieces on the backside of the project and used a length of bamboo placed in the routed line with glue to give it some added strength. So far this works. Since the backside is not visible it seems to work for when I have to use Cocobolo.
    (maybe a picture would help to illustrate my joinery)

  20. Eric April 18, 2013 at 7:14 pm - Reply

    What are you using the Cocobolo for, and what kind of joinery is being used?

  21. Curly Pio April 13, 2013 at 12:31 pm - Reply

    Other Ideas?
    I have tried solvents to clean, rough sanding the surfaces to be glued and used Gorilla glue on Cocobolo.
    It seems to bond well until heat comes into the equation which seems to cause the bond to release.
    Any ideas? (besides keeping it away from heat)

    • edad January 20, 2014 at 8:28 pm - Reply

      As a boat builder and luthier Id never use a water based glue on oily hardwoods,its just not worth the trouble. epoxy only. my .02 cents.

  22. Boatwood101 February 20, 2013 at 5:02 pm - Reply

    Use epoxy, I recommend system 3 brand “silver tip” i have had good results with it on teak. you will have to cut the teak thinner than 1″ or it will not take that bend without breaking. Based on your pic and dimensions, i would try 1/2″ or thinner. If you do manage to make it work with the thicker pieces, there will be an incredible amount of stress locked in the part that will result in a lot of “spring back” and early failure. Make sure to wipe all surfaces to be bonded VERY WELL with solvent (acetone, MEK, lacquer thinner, xylol, naphtha) untill the rag comes up clean before bonding. Hope this helps

  23. Dreamweaver Hardwood Hammocks February 15, 2013 at 7:35 pm - Reply

    I have a bunch of these laminated Larch Stands, but I would like to try the same design with laminating 4 1″ thick x 4″ long x 1.9m long Indonesian teak wood together into a curve. Does anyone recommend a type of glue that is fast drying and has a strong bond with Teak? Also does anyone know how much compressive strength would be the best?

    It would be kiln dried, Premium or A grade teak. Does anybody have any experience with something like this and think 1″ thick maybe too thick and would crack?

    Any recommendations are greatly appreciated.

    Thanks and regards,
    Kyle

  24. caliente guitars February 6, 2013 at 6:45 am - Reply

    good morning Tony
    could you please send me and post a couple of picks?
    will give you answer asap
    my email
    sibemol2club@gmail.com

    thanks a lot

  25. Tony Sloan February 4, 2013 at 11:32 pm - Reply

    Hello. I am debating buying what appears to be a VERY nice used classical guitar whose Indian rosewood bridge has separated from the body’s top/soundboard which is red cedar. However, I am unfamiliar with exactly how to go about re-attaching the bridge to the cedar given the oil issues mentioned above. Logically, there must be a standardized type of approach to this issue since virtually all red cedar topped classical guitars have rosewood bridges and for them to rip up like this isn’t very common. I would seriously appreciate any and all information about the best way or a standard way to re-attach this bridge so that it will stay adhered to the red cedar top. Thank you so very much in advance!…Tony

  26. bryan January 30, 2013 at 9:05 am - Reply

    One of the suggestions I could make that if possible or when possible to mortise out a section of the two pieces being glued together and incerting another, glue friendly wood, to bond the two together. The mortise would be an inset so that the true wood would show and not the insert; if that makes sence? The inserted wood could be slotted in place like a dowel, or small screws which are resesed below the surface of the softer wood will hold it in place. Just thinking outside the wood box.

  27. caliente guitars January 2, 2013 at 10:25 am - Reply

    good day
    about this 3 possibilities

    1 poliurethane glue
    2 epoxic glue
    3 cianocrylate

    which one do you think it is best for gluing hard woods between
    in middle measured pieces???

    (sorry if my english it is not the best)

    thanks a lot

  28. caliente guitars January 2, 2013 at 10:19 am - Reply

    good afternoon

    i am just making some investigations about gluing hard woods
    here in colombia about amazonas you can easelly find out 50 species of hard woods
    worst of all it is lignum vitae and some very similar to that,,
    tabebuia impegitinosa or sapan for example
    i am highly interested on trying cianocrylate on fretboard joint
    and any non water based glue,,
    lignum vitae it is extremelly hard one that absolutelly do not
    tolerate any water based glue,,after 3 days starts to open,
    and gives a lot of problems,,if you add to this fact that
    this hard woods hot a lot when sanding it is a real big problem
    thanks a lot

  29. Maximus December 26, 2012 at 4:24 am - Reply

    Hello Ignitious

    It is not possible, so you had better not try

    Love from

    The Internet

  30. ignitious November 21, 2012 at 5:32 am - Reply

    Hello

    I love leadwood and i in my country it is not protected, so i wanted to make a log cabin, is it possible?

    kind regards
    Ignitious

    • edad January 20, 2014 at 8:25 pm - Reply

      Tropical hardwoods have tons of natural oils in them ,the oldschool trick of cleaning the surface with acetone still works great, just be sure to do your gluing within an hour but no less than 30 minutes. That way the solvent has gassed off and the oils have not started to return to the surface. West systems with the normal catalyst not the fast one. is my first choice, with a close second to system 3. Works on teak and cocobolo, Ipe, canary, and other rosewoods and bocote to name a few.remember dont over tighten your clamps bring it up tight and firm but dont squeeze out all your epoxy.

    • edad January 20, 2014 at 8:25 pm - Reply

      Tropical hardwoods have tons of natural oils in them ,the oldschool trick of cleaning the surface with acetone still works great, just be sure to do your gluing within an hour but no less than 30 minutes. That way the solvent has gassed off and the oils have not started to return to the surface. West systems with the normal catalyst not the fast one. is my first choice, with a close second to system 3. Works on teak and cocobolo, Ipe, canary, and other rosewoods and bocote to name a few.remember dont over tighten your clamps bring it up tight and firm but dont squeeze out all your epoxy.

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