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Bleach or oxalis acid?
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=53467
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Author:  bcombs510 [ Sat Aug 29, 2020 9:24 pm ]
Post subject:  Bleach or oxalis acid?

Hello,

I have a nice set of ziricote that I’m using to build a uke. It’s got a bit of a greenish area in the sapwood. I think it will be fine either way but thought about maybe trying to bleach it away. Would I perhaps be able to remove it without also discoloring the same area I’m trying to fix?

Image

Edited to add: This was visible before I began taking the plate down to final thickness. It’s all the way through.

Brad


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Author:  Chris Pile [ Sat Aug 29, 2020 10:54 pm ]
Post subject:  Re: Bleach or oxalis acid?

Actual bleach is tricky - sometimes it turns the wood green.

You can try oxalic acid, or one of those 2 part wood bleaches that uses hydrogen peroxide. I've done both - good results when following the directions.

Author:  bcombs510 [ Sat Aug 29, 2020 11:05 pm ]
Post subject:  Re: Bleach or oxalis acid?

Thanks, Chris. I will give it a shot. There is a little bit of the green on the part of the plate that I cut off, so I can actually test on scrap! :D


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Author:  Chris Pile [ Sun Aug 30, 2020 4:56 am ]
Post subject:  Re: Bleach or oxalis acid?

Remember to neutralize whichever method you use when you've gotten the color you like.

Author:  Ruby50 [ Sun Aug 30, 2020 5:26 pm ]
Post subject:  Re: Bleach or oxalis acid?

You will have to apply whatever you use over the entire light colored grain and try to make a definite line where the light/dark happens. If you put it on just part of the light area there will be a color change in the light area.

Ed

Author:  bcombs510 [ Sun Aug 30, 2020 9:44 pm ]
Post subject:  Bleach or oxalis acid?

Ruby50 wrote:
You will have to apply whatever you use over the entire light colored grain and try to make a definite line where the light/dark happens. If you put it on just part of the light area there will be a color change in the light area. Thoughts?

Ed


Good to know. Here is a full pic of the back in question. Given the amount of sapwood it might be hard to keep it all uniform.

Image

Brad


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Author:  Clay S. [ Mon Aug 31, 2020 8:45 am ]
Post subject:  Re: Bleach or oxalis acid?

I have had mixed success with wood bleach. If you leave it too long (or strong) on the wood it can actually "eat" some of the fibers and leave voids to fill. I would wet the entire area of the sapwood with water first and then apply the bleaching agent to the stained area. The water will help dilute and diffuse the bleach in the area that doesn't require bleaching. It is sometimes better to do several dilute treatments than a single concentrated one.
If you don't have any luck removing the stain, you might have better luck staining the stain and the rest of the sapwood to match it. Rubbing a dark pigment powder into the pores and then staining the sapwood with a lighter brown dye stain might help hide the discoloration. As with most finishing issues - test on scrap to see if you like what it does first.

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