Bleaching Dark Panels for a "Reverse Sunburst"
Finishers consider ways to approach bleaching just the center of a dark Bubinga panel. July 3, 2008
Question
I have a job that requires us to create a reverse sunburst finish. We are starting with a panel of bubinga and need to fade the center of the panel to a much lighter color, much like a traditional guitar finish, but applied backwards. My first thought is to use wood bleach, but having not much experience with it, I am not sure. I thought using bleach in a spray bottle might aid in the fading, but I am afraid it will spread too much.
Forum Responses
(Finishing Forum)
From contributor C:
Do you mean kept darker/natural in the center and lighter as it goes outward to the edges? If so, is the panel square, rectangular, other? Is it to be as uniform as a sunburst finish? How much lighter does it need to fade out to?
From the original questioner:
The panel is rectangular, and by reverse sunburst, I mean it is medium dark now and needs to be faded lighter in the center and left alone along the outside edges. It doesn't need to be entirely uniform like a guitar, but the fading needs to be controllable. We are trying to get it from the dark bubinga color to something approaching light cherry if possible. Not looking to bleach it completely white.
From contributor C:
Just a suggestion... Mask off the panel area you want to stay original color, seal the rest in with vinyl sealer or nitro, remove the masking and this will allow you to see how much the lightening affect is proceeding when you apply the bleach. Keep a close eye on the progress and be ready to wash off the bleach when you get to where you want to be. If it starts foaming, wipe off with dry rags so you can see. Stop the process by neutralizing with white vinegar, allow to dry overnight - wash off sealer coat and ready it to receive the finish you plan on using. If vinyl, you won't have to strip, just catch those areas up with the rest.
From the original questioner:
That sounds like a good plan. Can you recommend any particular bleach product or are they all about the same? Would using a spray bottle make the fade more even or would that just get washed over with the vinegar anyway?
From contributor C:
Any two part should do, but make samples first! You can try the spray bottle, or if you have a Teflon cup gun and SS gun, you can use that to apply it by just misting on with *good* ventilation and mask and gloves, etc. Be careful.
From contributor C:
You can also then gun shade around the center to fade it out more gradually if you'd like a more appropriate look like on a guitar. Just mix up a dye/stain close to the original color and apply sparingly, darker at the center, lighter towards the edge.
From contributor L:
It might be easier to bleach the whole thing and then toner in the area you want darker. Like contributor C laid out using the dye.
From contributor R:
Would that be called a "Moonburst"?
From contributor C:
Let's call it the corona effect. I was thinking also if the 2 part bleach lightens too much, you could just use the hydrogen peroxide without the sodium hydroxide for better lightening control. Samples, samples, samples. Also, if you want a softer line, instead of the hard line you'll achieve by masking, you could place the proper size rectangle in the center and gun apply the bleach lightly and (at an angle) produce a hazier affect.
From the original questioner:
I get the idea that you think highly of samples. I will give a couple tries over the next few days and let you know how it turns out. Thanks for the help.
From contributor Y:
It's been a long day.
"...mask off the panel area you want to stay original color, seal the rest in with vinyl sealer or nitro, remove the masking and this will allow you to see how much the lightening affect is proceeding when you apply the bleach."
If you mask what you want to leave unbleached, seal the panel, remove the masking, and bleach, won't you get the reverse of what you want - won't the area you want to stay the same be the only area bleached?
From contributor C:
Sorry. I just re-read. Yes, you would seal in the area you do not want to change color and bleach the rest.
From contributor G:
How about bleaching the whole panel and then sanding the edges back to original color?
From contributor C:
That would work too. There are a lot of ways to do it. Depends on exactly the look one is after. That's why I said make samples.
From contributor C:
Just an update - the samples turned out well. They were bleached lightly with two part wood bleach then wiped with oxalic acid, which at least doubled the bleaching effect. I am going to try sanding the edges of the bleached area to fade the color change, as the bleach line is pretty sharp and I want a real faded effect.
