View Full Version : Staining/Darkening Okoume
Clinton B Chase
05-04-2007, 09:53 PM
I love Okoume plywood except when it comes to varnishing it. I have heard from a reliable source thay a 5% Potassium Permanganate solution will darken mahohany nicely. I wondered what the other options are in terms of stains that could go on prior to varnish. I want a darker tone to the Okoume.
05-04-2007, 11:35 PM
I used Minwax oil stain on the Bruynzeel Okoume plywood floorboards I built for my Avon Rover and varnished them. It killed that pinky color and they looked good and worked fine. When I replaced the motor well on an old Simmons Sea Skiff, we used 3/4" Okoume, stained it with alcohol-based stain and then epoxy coated and varnished it. No problems, though alcohol stain is somewhat tricky to apply evenly because it dries in a minute or so.
05-05-2007, 08:16 AM
Potasium Dichromate. Permanginate works better on softwoods. But both are fairly toxic. I used to use Potasium Dichromate on a lot of my furniture, but not anymore.
Andreas Jordahl Rhude
05-05-2007, 08:33 AM
I have used Okume plywood on numerous power boat restorations. I have stained the wood with Z-Spar red mahogany filler stain and also their brown mahogany. I have never had any problems with the stain. I then varnish on top of the stain. Always has looked great.
I am trying Meranti plywood on my current Thompson Boat restoration for decks etc...
05-05-2007, 09:20 AM
I've had good luck with water soluble wood dyes from WD Lockwood http://www.wdlockwood.com/
Which I actually purchased from this company: http://www.toolsforworkingwood.com/Merchant/merchant.mvc?Screen=CTGY&Store_Code=toolshop&Category_Code=CLWW
Good, though overly elaborate (IMO), instructions for staining your plywood can be found here: http://www.clcboats.com/shoptips/shoptips_stepbystepstaining.php
Does anyone have any experience epoxying over stained wood?
I'm building a Simmons Sea Skiff 18 and want to stain the Okoume plywood transom and finish bright. Everything else will be painted. The epoxy will be purely a coating and not structural. (I'll keep stain off the glued surfaces.) I'm worried that an oil base stain will act as a mold release and the epoxy won't stick. Currently, I've stained it with a common water-based stain - but it's raised the grain considerably. This may or may not be a problem - epoxy will probably level the surface off pretty well, but I'm not sure. My thinking is that the water based stain should leave only pigment and not anything oily to which the epoxy might not stick.
05-10-2007, 12:00 PM
Either water-based or alcohol-based stains will work under epoxy without compromising the bond. Both will raise the grain more than oil stain usually does, but if you then build up the epoxy to the proper thickness, it likely won't be a problem. You can always put on a coat of stain, let it dry, rub it down with sandpaper or a Scotchbrite pad to knock down the grain and then add more stain. Both these types of stain have much shorter time windows for wiping and blending the wet stain than oil-based, so building up the color with multiple applications of more diluted stain often produce a more even staining job than trying to get all your color on evenly in one application. It's also possible to raise the grain and sand it smooth with water as preparation, before staining. You may still likely get some grain-raising from the stain, but it will be less.
When I re-built my Star, I applied alcohol stain to the sanded mahogany, let it dry and then rubbed the surface down a bit with a scrap of canvas. Then it got another coat of stain, another rub-down, six thin, rolled and tipped coats of WEST epoxy (105/207) followed by final sanding with a random orbit to about 100 grit and topped off with rolled and tipped Captain's varnish.
I also used alcohol stain on the Simmons I rebuilt. Of the stained parts (bow deck, transom, motor well, seats, steering assembly, seat risers,etc.) some then got epoxy and some just varnish.
Potassium Permanganate produces brown on woods lower in tannin, while Potassium Dichromate creates vibrant red/brown on African Mahoganies, Honduran, and Cuban depending on concentrations and the many variation in the wood chemistry itself. I just layed some up on Okoume a couple of minutes ago, so will report back on the reaction. If it is blah, I'll do another swatch using tannic acid first, and another with Permanganate. All of the hexavalent chromium compounds are bad, but your idea of "treating" okoume with it could not only dye the wood, but will increase the durability of the wood in that nothing can survive Dichromate. Will keep posted
Clinton B Chase
05-10-2007, 09:16 PM
Good stuff. This makes me more excited about Okoume with all these options. Keep up the discussion...I am learning a lot.
Okay, it's getting late but here is some results. Tannic acid will definitely make the okoume "pop" under the dichromate, but the okoume alone makes me think butternut, although this is a weak solution I use to start.
Left to right
Okoume with my standard solution, Same solution on "light" African Mahogany applied at same time (dramatic, eh?), The piece on top is AM with 2 coats of a weaker dichromate solution that has been exposed for a very long time (weeks of sunlight, etc.), Un-treated Afr. Mah., Afr Mah fumed for 18 hours.( Darkest ).
All of the Afr. Mah. is from the same slab, so the color change is indicators of the solutions and methods ( fumed ), I also tweeked the photo to match screen color as best as possible.
I will take some time to put together something better for reference tommorow, side by sides with Cuban and Honduran , well might as pile all of my wood swatches together.
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