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Main Boards => The Bowyer's Bench => Topic started by: Buemaker on March 09, 2020, 04:03:30 PM
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I plan to put together a couple of recurve limbs using thin Macassar Ebony veneers under clear glass.
Does anyone have experience gluing this wood species?
According to Wood Database this species because of high oil content and density can be difficult to glue.
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I made a one piece recurve with Macassar Ebony veneers under clear glass. I think it was 9 years ago. I know the guy who owns it and The Bow is still shooting. I don't recall any problems gluing it up with smooth On, I always use plenty of Smooth On and apply over veneers 3 or 4 times. The macassar did darken up alot with the epoxy like most wood does.. but since the Macasser Ebony was already dark brown and almost black there is not much contrast..like you see with black and white ebony.
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some of the Macassar Ebony veneer I had was even darker than this.
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As said above they will tend to get pretty dark under glass. The “oily “ wood theory is just that. A theory. The culprit to bad glue ups is wood that isn’t dry and or not properly prepped. Tons of bows out there with “oily” woods for veneers. Veneers tend to dry pretty quickly though. If your cutting your own veneers get them to spec (the thinner the better) and let them sit in a controlled environment for a few days before gluing them up. I like to go over them lightly with a heat gun just before glue up. I also let them sit for about 4 hours or more before going into the heat box to help minimize gassing.
All this is just my opinion so...
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If the moisture content is good clean and prep should have no problems. Like already mentioned wood under glue and glass gets darker. If you got about 50/50 dark and tan mix in you wood will look good tho.
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Okay, thank you.
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If you want some insurance, you could try System Three G-2 epoxy. It's quality stuff. Here is their copy;
"For over 35 years, G-2 has been an excellent adhesive choice for oily, acidic hardwoods like teak and other tropical woods. Use it for gluing oak and cedar, as well as other materials that are difficult to bond. G-2 was developed primarily for waterproof bonding of rot-resistant woods used in fine yacht joinery. Use G-2 for both interior and exterior applications as well as below the waterline. G-2 can be mixed in small or large batches, has a long pot life and cures overnight. No clamping pressure is required. After fully curing it can be machined, drilled, sanded and tapped".
It was previously made by Industrial Formulators out of Canada. I used their G-1 for years before they sold to System Three and it was discontinued. It was the finest epoxy I have ever used. I do use a couple of System Three products, but find them a little spendy.
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Is it flexible Flem? :dunno:
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Is it flexible? Oh Yeah!
EA-40 elongation: 1%
G-2 elongation: 11%
I use Smooth-On Exoxamite 102, which is 3.15%
The bench mark is West Systems 650 G-Flex, but they don't give a static elongation figure. Maybe someone with an engineering background could translate the figures, I can't.
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Flem, do you use it to glue up a bowlimb, both glass and wood?
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Following :bigsmyl:
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I have used all of the above epoxy's to glue all wood and wood/glass bows. No issues with any of them.
I favor the Exopamite because of it's viscosity and quick gel + set time.
The only wood I have ever had delamination issues with is Osage, which was my shortcoming. I have glued up a lot of greasy woods with Epoxamite, but if I ever were to use Osage again I would get some G-2 just for insurance.
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Macassar is not oily in comparison to many other exotics. I have never found a wood that was "DRY" that I couldn't glue with smooth on. Have done a few mac veneers and found that I must be very particular about the veneers I pick as they can get so dark that they resemble black glass only uglier if that is possible :)
If you've had a glue failure with exotic wood, it is most certainly moisture to blame and not oil. I'm sure there are some exceptions, but they would be rare.
BigJIm
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I just glued up a handle using Lignum Vitae, It's a really interesting wood. Most dense and heavy in the world. (https://en.wikipedia.org/wiki/Lignum_vitae") It's far more oily than any of the Rose woods or coco bolo that I've ever worked with. I had read how hard it was to glue up so I was worried about how it would go. I wiped it all down several times with acetone and glued it up with smooth on. It seemed to come out real well.
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Badlands, it will be fine if you used smooth on and the wood was dry.. The harder they are, the harder and longer they are to dry.
BigJim
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Big Jim, I've had far more problems with having oily woods crack then I have had with glue joints failing. I can't really remember having a glue joint fail but I don't think that I have ever made anything out of Coco Bolo that hasn't developed come cracks eventually.
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Badlands, those cracks are developing from excess moisture escaping... unless they are put in a compromising position. I rarely if ever have bows come back with cracks... at least a rare occurance since I moved my entire shop and most of my wood storage in to a climate controlled building.
It also helps to have wood sitting around in that building for years and years drying to equilibrium.
BigJim