View Full Version : Mahagony restoration

08-16-2008, 07:35 AM
Hello All,

I have been sanding the mahogany transom an my restoration and have noted the wood has a grayish tinge in places..from exposure to the elements I presume and neglect. I have sanded it but it has not all come out. Any suggestions on how to get to a more original shade without oversanding? Will varnish take out the gray?

Thanks everyone.

C. Ross
08-16-2008, 08:05 AM
It's basic oxidation from exposure to water and air. The fix is to bleach, and it's easier than it sounds:

Remove all of the finish. Bleach with oxalic acid (you can buy it at the hardware store) and rinse. When it's dry rub a rag with mineral spirits or turpentine over it to see if the color looks even. If not bleach again. Sand with 150 grit, seal, stain, varnish, sanding as appropriate in-between. It'll be beautiful.

Bill Lowe
08-20-2008, 03:58 AM
Here is a couple of photos stripping and staining.

08-25-2008, 08:14 AM
Home Depot sells a gallon of concentrated oxalic acid wood bleach. I just use it straight and brush it in. Let it dry and then rinse it off.

It cleans up many stains in wood and restores the color. Works great on mahogany. It will take out all the grey color.

HD also sells a concentrated phosphoric acid concrete cleaner etcher. You can use this on wood to try and remove stains that might not come out with oxalic acid.

For stripping I like citri-strip. It works great, does not dry out fast and takes out oil wood stain. And you can rinse with water. It will even strip epoxy if you cover with plastic and let it work for a day.

try to do as little sanding as necessary. The wood is not getting any thicker with time.

08-25-2008, 08:24 PM
Thanks for all the input.

I have tried the Oxalic acid and it has worked pretty well. There are a few stubborn stains that I may try the concrete wash on..do I let it dry or wash it off before that happens? I have one stain on the rudder that looks oily/wet but will not budge and feels dry to the touch!? Any ideas what that might be?

Further to this discussion..the interior finish is varnish that looks like it has a slight purple tinge to it..and it's quite hard to remove with sanding only. I think it may be a stain that was varnished or does some varnishes just age to that colour?

Again, any thoughts/ideas are welcome.


C. Ross
08-25-2008, 08:36 PM
Try this? For the stubborn stains, mix up dry oxalic into a slurry like beach sand, and let it sit for a couple of hours. Put a couple of drops (literally) into the mix every couple of hours keep it damp if you want, then wash off the next morning.

The stain on your rudder might be rot -- is the wood soft?

Before you use the concrete etcher, read your duplicate version of this thread. pcford had the program on how to use two-parts -- you DEFINITELY need to use the second part of a two-part bleach.

08-25-2008, 09:52 PM
Mr. Ross,

Thanks for the reply. The stain on the rudder is not soft or wet..I'm stumped!

C. Ross
08-25-2008, 09:55 PM
Stumped here, too. Do you have any pictures of the odd spot, and the purplish varnish?