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Discussion Starter #1
I am refinishing a small built-in cabinet with an ash face-frame. I have sanded it down to the raw wood, and there are some color differences between the different frame pieces. Most are light amber tones which are just fine, but a few pieces are light grey-green and just don't match the rest. It would be simpler if wanted to go darker, but if possible, I would like to color match and end up with something in the white to light amber range.

Most of what I read about bleaching does not address color mismatch. Is bleaching going to make these pieces consistent in color, or is there always going to be some mismatch?

If bleaching is the way to go should I just attack the grey pieces, or do all of them?
 

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First it isn't a good practice to sand a finish off when refinishing. When you sand a finish off you get what is on the surface and not what is penetrated into the wood. When you use a chemical paint remover it removes all the finish and it also tends to remove some of the stain too. If you think you have the finish thoroughly sanded off then bleach may be effective. If there is any of the finish left then the bleach will do nothing. All you can do is give it a try and see what happens. Household bleach works pretty good but the two part wood bleach is stronger. Just use the bleach on the parts you are unhappy with. Then it will need to be sanded again. I would wear a chemical respirator sanding wood that has had bleach on it.
 

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If you are planning to bleach the wood, you must use a chemical paint stripper to completely remove all the prior finish. Sanding will not remove the finish that has penetrated into the wood and any residual finish will cause any new stain to color unevenly.

As to stain, there are three used in woodworking. Chlorine bleach (swimming pool chlorine) is used to remove absorbed dye stain. Oxalic Acid is used to remove mineral stains like those from water stains. Finally, two part A/B bleach is used to remove the natural color of wood. As you can see, none are used to change the color of a finish. For a finish, you must mix your stains to achieve the color you want.
 

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Discussion Starter #4
The wood was previously painted. After sanding, it does not appear to have any residual finish in the wood - water soaks right in and darkens the wood. I am trying Oxalic Acid right now since it is the cheapest and supposedly kindest to the wood.
 

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What you can expect to happen if you thoroughly sanded the wood is the majority of it will bleach alright but there will be a spot here and there that will do little or nothing. It won't hurt anything but you may have to go back and do some additional sanding on those spots.
 

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What is your objective in using a bleach? What are you trying to accomplish?

As I said previously, oxalic acid is used to reduce or eliminate mineral, metal or water stains from wood. It does not appreciably change or lighten the color of the wood. Be sure to use a borax to neutralize the oxalic acid or a finish will not adhere to the surface. Old fashioned "20 Mule Team Boraxo" works well as a neutralizer.

Use properly, none of the above above bleaches will damage the wood.
 

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Discussion Starter #7
So far, the oxalic acid has succeeded in bleaching the wood slightly. The grey pieces are lighter and look reasonable when dry. There is still a difference in color between the grey and the brown pieces, but the lighter it gets the less contrast I see. I'd try the 2-part bleach but locally it is only available in expensive 1gal containers, when I only need maybe 1pt.

I have been using water-based acrylic and I'll have to spot test to see if it darkens the wood any. No point in bleaching if the finish changes it back to the way it was before.
 

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I am refinishing a small built-in cabinet with an ash face-frame. I have sanded it down to the raw wood, and there are some color differences between the different frame pieces. Most are light amber tones which are just fine, but a few pieces are light grey-green and just don't match the rest. It would be simpler if wanted to go darker, but if possible, I would like to color match and end up with something in the white to light amber range.

Most of what I read about bleaching does not address color mismatch. Is bleaching going to make these pieces consistent in color, or is there always going to be some mismatch?

If bleaching is the way to go should I just attack the grey pieces, or do all of them?
You may get lucky with wood and get pieces that are consistent in grain and color. Wood is a product of nature, and can have great differences, or minimal ones. Some of that problem can be solved in the initial selection of the project pieces.

You could try experimenting with bleaching out the discolorations, or make a pickle solution to lighten them. I'm thinking that an overall bleaching attempt will change the entire face, not just the grain you want to lighten.






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The two part bleach is a good idea. If that doesn't do it you may have to put a very light stain on those pieces and stain the rest of it to match.
 

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Discussion Starter #10
I broke down and got the A B wood bleach. It is very expensive now due to the high shipping cost for hazardous/high voc materials, but I was able to buy the 2gal 'kit' locally for $50 (it would be $90 online).

I pre-mixed a small amount and used a nylon brush. There was no obvious activity, but when it dried it had indeed lightened the wood. I used a second application, and then neutralized with diluted vinegar followed by clean water the next day. The final result was very nice with little color differences between pieces.

I knew that my water based finish would darken the wood a bit, but I got a surprise. Most of the brown tones I had before are now yellow, and the grey-green tones are just lighter grey-green. It wasn't the result I was after, but it is lighter and I can live with it. What I really wanted was to preserve the very pale color and hue I achieved with bleaching. Other than continued bleaching to make it super-white, is there a finish that could do this?
 

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If you used two applications of the wood bleach I imagine you reached the limit of what was possible. When wood is stained sometimes it's not possible to get it all out. Before you put a finish on it could you post some pictures. You might be able to do a little shading with dyes or toners to at least get it all one color. It may also be possible to put a small amount of white pigment in your finish to lighten some of the spots you are unhappy with.
 

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Discussion Starter #12
Pic1 is the pre-bleach cabinet - too dark and mismatched.
Pic2 is after oxalic bleach, no finish. The A,B bleach (no pic) left it much lighter than this with just a hint of color.
Pic3 is final finish. Quality pics are hard to do, and lighting is a big factor, but the right side is more yellow, left side has grey-green verticals.

My lessons:
Would have been less labor to replace the wood than try to fix it.
Pick the wood putty after you know what the final finish will look like.

Some day I may revisit this but for now its done.
 

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From what I can see it just looks like a natural difference in the color of the wood. You could go over the lighter areas with a aniline dye stain or a toner and color it to match closer to the faceframe if you choose to work on it again. I bet the doors and drawer fronts were plywood and they just finish different anyway.
 

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Discussion Starter #14
The color mismatches I have been trying to fix by bleaching are just the face frame ash pieces. The new drawer/door fronts are all solid maple. I expected there to be some contrast between the maple & ash, I just wanted there to be a consistent contrast. Attached is a closeup showing perhaps the worst of the ash mismatches.
 

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It would have been more effective to alter the color before the finish was put on. The ash wood that is more gray could be dyed with more brown tones and the maple could be dyed with more gray tones to even it up. It can still be done over the finish but you would have to make a lesser adjustment.
 

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In looking at the faces and face frame of the cabinet, you can see why I mentioned doing a wood selection before starting a project. You would still have to jump through hoops if you tried to match up the differences before assembly. It's so much easier to use the same wood throughout, than go to all the trouble of trying to make one look like the other.

If you have some scrap samples, you could try using a pickling finish (white wash), or a thinned version of a pickle, to see how it blends out the dark grain on woods. It may be enough.






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