Finishing Exotic Wood

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Finishing Exotic Wood

Postby Bob Gerard » Mon Feb 12, 2018 10:23 pm

I have a question regarding the finishing for Exotic Wood, namely Bloodwood (and later on, Bubinga). Due to the high oil content in these woods, normal Polyurethanes will not work- virtually never dry.
I have read that De-waxed Shellac is used as a sealer on which you can apply Poly or another finish, or just use Shellac like in a French Polish.("Shellac sticks to everything and everything sticks to shellac")
So, I have the De-waxed Shellac flakes, the denatured alcohol and am ready to mix my own Shellac.
The question I have is this: Do I wipe down the Bloodwood with acetone and allow it to dry before wiping on the Shellac, or can I just apply the Shellac right on natural Bloodwood surface?
I plan on running some experiments on scrap pieces of Bloodwood from my current dulcimer project, but would love some ideas from friends here.
Thanks for any help on this one!
~Bob
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Re: Finishing Exotic Wood

Postby asterhunter » Tue Feb 13, 2018 6:21 am

I found a few articles on Bubinga and as you have mentioned, they are a great looking wood but have problems with gum deposits. I found brief advice on working with Buginga (turning, sanding, etc) but nothing turns up about staining or finishing. Perhaps the gum deposits prevent the wood from being a good candidate for finishing. One thing I did turn up, the wood is good for turning or lathing, but is not recommended for steam bending.

David Elosser
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Re: Finishing Exotic Wood

Postby KenH » Tue Feb 13, 2018 7:54 am

Can't help with the shellac, Bob, I've never used it (but I did sleep in a Motel 6 last night!). I have applied urethanes to both bloodwood and bubinga, but would not recommend wiping them down before hand.

Personally, I prefer to finish exotics (which I work with a lot) with Tung Oil. I usually use the matte version, but have seen some nice results from glossy tung oil applications.
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Re: Finishing Exotic Wood

Postby Bob Gerard » Tue Feb 13, 2018 2:55 pm

asterhunter wrote:I found a few articles on Bubinga and as you have mentioned, they are a great looking wood but have problems with gum deposits. I found brief advice on working with Buginga (turning, sanding, etc) but nothing turns up about staining or finishing. Perhaps the gum deposits prevent the wood from being a good candidate for finishing. One thing I did turn up, the wood is good for turning or lathing, but is not recommended for steam bending.

David Elosser


Hi Dave- I just bent a side set of Bubinga- 1/'8" thick x 2" high, using my standard method of submerging the wood in a pan of boiling water for 30+ minutes and it worked pretty well . No issues getting them into the bending jig. Hopefully they will retain most of the shape when I take them out later in the week. It's a lovely looking wood and I read that is a good substitute for Rosewood by some guitar makers. We'll see how it works on a Butternut topped dulcimer :)
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Re: Finishing Exotic Wood

Postby Bob Gerard » Tue Feb 13, 2018 4:11 pm

KenH wrote:Can't help with the shellac, Bob, I've never used it (but I did sleep in a Motel 6 last night!). I have applied urethanes to both bloodwood and bubinga, but would not recommend wiping them down before hand.

Personally, I prefer to finish exotics (which I work with a lot) with Tung Oil. I usually use the matte version, but have seen some nice results from glossy tung oil applications.

Oh- I hadn't ever tried Tung Oil :idea:
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Re: Finishing Exotic Wood

Postby asterhunter » Wed Feb 14, 2018 12:36 pm

Bob Gerard wrote:
asterhunter wrote:I found a few articles on Bubinga and as you have mentioned, they are a great looking wood but have problems with gum deposits. I found brief advice on working with Buginga (turning, sanding, etc) but nothing turns up about staining or finishing. Perhaps the gum deposits prevent the wood from being a good candidate for finishing. One thing I did turn up, the wood is good for turning or lathing, but is not recommended for steam bending.

David Elosser


Hi Dave- I just bent a side set of Bubinga- 1/'8" thick x 2" high, using my standard method of submerging the wood in a pan of boiling water for 30+ minutes and it worked pretty well . No issues getting them into the bending jig. Hopefully they will retain most of the shape when I take them out later in the week. It's a lovely looking wood and I read that is a good substitute for Rosewood by some guitar makers. We'll see how it works on a Butternut topped dulcimer :)


Let us know how that works. The articles I dug up are aimed at furniture and flooring manufacturing. A piece like you are using might work fine for bending, hopefully. Probably the issue with bending is a combination of the high wood density and gummy deposits that might create glueing issues.

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Re: Finishing Exotic Wood

Postby Bob Gerard » Wed Feb 14, 2018 10:18 pm

Hi Dave- I will certainly let you know how it works out.
The wood is very dense indeed though not brittle (like the Bloodwood I am using on another project) which helps.
For "gummy wood" I think you mean "oily wood"? That can be an issue for gluing with water-based glues, but I have been cleaning the gluing surface with acetone which removes the oil and allows a good, dry surface.
I am leaving the side slats is the form to completely dry for a few more days. But I fear there will be some/much 'spring-back'. I will take my heat-gun to them, which has been a great bending tool.
I hope it works :roll:
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Re: Finishing Exotic Wood

Postby KenH » Wed Feb 14, 2018 11:23 pm

"Gummy" wood is like pine, which can have pockets of sap that harden over the age of the tree, but the sap can soften and ooze when you start to work the wood.
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Re: Finishing Exotic Wood

Postby Ken Bloom » Thu Feb 15, 2018 9:59 am

It can never hurt to wash the surface with acetone first to remove any surface oil. I use shellac all the time. Once you seal the surface with a coat of shellac, you shouldn't have any further problems with whatever finish you put on top of it. When I do an instrument out of cocobolo I always make the first coat shellac. I can then go ahead and varnish with no problems. Mixing fresh shellac is also easy. I use a clean glass jar. Put the flakes in and pour in the alcohol. It will take a while for the flakes to dissolve. I use a higher flake count than most so it usually takes several days for the flakes to completely dissolve. One other tip. always use fresh shellac. If it is too old, it won't dry. For me, it's never around long enough to get that way. I just mix it up in small batches and start a new one when it gets low. I hope these tip help.

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Re: Finishing Exotic Wood

Postby asterhunter » Thu Feb 15, 2018 10:25 am

Bob Gerard wrote:Hi Dave- I will certainly let you know how it works out.
The wood is very dense indeed though not brittle (like the Bloodwood I am using on another project) which helps.
For "gummy wood" I think you mean "oily wood"? That can be an issue for gluing with water-based glues, but I have been cleaning the gluing surface with acetone which removes the oil and allows a good, dry surface.
I am leaving the side slats is the form to completely dry for a few more days. But I fear there will be some/much 'spring-back'. I will take my heat-gun to them, which has been a great bending tool.
I hope it works :roll:


I meant to write "gum" deposits. As the wood is worked, planing and sanding, the gum leaches out dulling blades and clogging sanding surfaces. It's impact on glueing is only speculation on my part, but it looks like you have some great advice here on cleaning your piece before installation. Proper kiln drying can minimize the gum issue, so not all Bubinga wood may have this problem. If this works out and you want to use more Bubinga wood, you might want to ask your supplier who is doing the drying and if they are setting the kiln proberly for this wood.

David Elosser
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Re: Finishing Exotic Wood

Postby Bob Gerard » Tue Feb 20, 2018 12:29 pm

So I did some experimenting with scrap pieces of Bloodwood and found that it is certainly best to wipe the surface well with acetone before applying De-waxed shellac. The shellac still picked-up faint traces of the wood's red color, but nothing to worry about. Brushing with the same shellac over un-cleaned Bloodwood, the brush became very red and the color bled, which would certainly have stained any adjoining woods (in this case, Northern Cherry).

So my shellac went on and dried to the touch in about a minute or two (I mixed the Shellac to a One pound cut= one ounce of dry de-waxed blond shellac flakes (from Rockler Woodworking) to a cup of denatured alcohol, and allowed to dissolve a good 24 hours in a sealed jar with occasional stirring to loosed any 'goop' on the bottom of the jar). I brushed subsequent layers and used a 400 grit sandpaper after the second and consecutive applications (wiping after each sanding). In all, I applied 4 layers of shellac on the dulcimer (Cherry sides and ends, Lacewood Tuning head, Western Cedar top and the Bloodwood bottom).

Last night, after letting the shellac cure for three days, I applied the first layer of Minwax Wipe-on Polly. (Over shellac, the Polly's first coat should allow to bond and dry a good 12 hours, after which subsequent layers dried to the touch in twenty minutes or so). It looks stunning. I will apply additional layers which will close the open pours of the Bloodwood and should look great.

It's been exciting to learn this new process and hope that in sharing this, others may benefit from my experience.

https://fotmd.com/bob/gallery/9921/dulcimer-i
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Re: Finishing Exotic Wood

Postby kwl » Wed Feb 21, 2018 4:19 pm

Bob, just curious as to the type of brush you used. Was it a bristle burst, camel's hair, or what? Thanks.

Ken
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