How to restore yellowed plastic parts.

Oranjeaap

Senior Member
Joined
Feb 25, 2010
Messages
9,108
Reaction score
5,154
I have a once white pickguard and once white plastic parts, however after 40 years they now all are a different shade of white. To make matters worse there were stickers on the pickguard, and after removing them the pickguard now has different areas of different shades.
Because there is no replacement parts that will fit this guitar without modification, I will first try to restore them back to their original color.
Any suggestions?
 

ARandall

Senior Member
Joined
Apr 16, 2012
Messages
16,854
Reaction score
14,680
I'm pretty sure the yellowing is a chemical reaction. So no going back. I think sanding them down to an unaffected layer might be your only option.
 

LtDave32

I'm walkin' on sunshine
Super Mod
Silver Supporting Member
V.I.P. Member
Joined
Mar 19, 2010
Messages
50,267
Reaction score
170,635
I have a once white pickguard and once white plastic parts, however after 40 years they now all are a different shade of white. To make matters worse there were stickers on the pickguard, and after removing them the pickguard now has different areas of different shades.
Because there is no replacement parts that will fit this guitar without modification, I will first try to restore them back to their original color.
Any suggestions?

I'll tell you something that a lot of builders might not know.

Plastic buffs up beautifully. Dare I say easier than lacquer.

You sand the offending layer down with some 320 or 400 grit until you are back to the color you want.

Then take it through the grits, wet. 600, 800, 1000, 1500.

Now you need a two-stage buffing compound(s). a heavy scratch remover, and a light polishing compound.

Finish the whole thing off with some Scratch X.

When I get a repair in, many's the time I've taken somebody's black PG and buffed it up with medium then fine compound, just to get the strumming scratches out. Comes out like a black mirror. You just won't believe what a little bit of sandpaper and compound can do.
 

fatdaddypreacher

V.I.P. Member
Joined
Feb 5, 2011
Messages
7,361
Reaction score
5,588
and i may get flamed for this, but not only i realized plastics can be buffed, I have actually made cavity covers from black clipboards. about as cheap as you can get tough, resilient plastic. they can also be laminated with other materials, like veneer, or thin sheet acrylics widely available on the tube.
 

ArchEtech

Gold Supporting Member
V.I.P. Member
Joined
Sep 15, 2007
Messages
2,237
Reaction score
1,380
Buffing works quite well on the plastics, I concur. It can also work on binding but you have to be really really careful.
 

Oranjeaap

Senior Member
Joined
Feb 25, 2010
Messages
9,108
Reaction score
5,154
I'm pretty sure the yellowing is a chemical reaction. So no going back. I think sanding them down to an unaffected layer might be your only option.
I'll tell you something that a lot of builders might not know.

Plastic buffs up beautifully. Dare I say easier than lacquer.

You sand the offending layer down with some 320 or 400 grit until you are back to the color you want.

Then take it through the grits, wet. 600, 800, 1000, 1500.

Now you need a two-stage buffing compound(s). a heavy scratch remover, and a light polishing compound.

Finish the whole thing off with some Scratch X.

When I get a repair in, many's the time I've taken somebody's black PG and buffed it up with medium then fine compound, just to get the strumming scratches out. Comes out like a black mirror. You just won't believe what a little bit of sandpaper and compound can do.

Thanks, I suspected this was the way to go.
 

the great waldo

Senior Member
Joined
Jan 5, 2010
Messages
534
Reaction score
327
Most of the newer plastics are pvc based and tend to change colour quite heavily. I've had a few Fenders where the pickguards went light brown. I gave up sanding and poilishing them as it was basically a waste of time. The round sticker marks were usually the worst as you'd have to sand off most of the top layer. You can by all means try but I don't hold up high hopes. It's easier and cheaper to just replace the pickguard. The older pickguards were better and did'nt react so much to the uv. and obviously black is not a problem as you just need to remove scratches and marks, although go easy with the buffing machine as you can melt or smear the plastic (depending n what kind it is)

Cheers
Andrew
 

Bainzy

Member
Joined
Jul 2, 2007
Messages
40
Reaction score
28
Hydrogen peroxide is a fairly popular method, people use it for everything from whitening synthesizer keys to Star Wars stormtrooper figures.

From memory the yellowing has something to do with a flame retardant mixed in the plastic like Bromine. The use of hydrogen peroxide and UV light as energy creates a reverse reaction, or so the theory goes. I've tried it myself and its fairly safe and works well, though you can end up bleaching coloured plastics too much if left in the sun too much.
 

Oranjeaap

Senior Member
Joined
Feb 25, 2010
Messages
9,108
Reaction score
5,154
Interesting!
I guess I will try the H2O2 first, I probably have acces to some. If it doesn't work like intended sanding will be the next step anyhow.
 

rockstar232007

Senior Member
Joined
Jun 28, 2008
Messages
18,125
Reaction score
16,722
Interesting!
I guess I will try the H2O2 first, I probably have acces to some. If it doesn't work like intended sanding will be the next step anyhow.
I would think it would be available in your country?

Doesn't need to be that strong. Most over-the-counter peroxides (various strengths) would work. Might take a little longer, but they'll work.
 

jk60LPTH

Senior Member
Joined
Sep 19, 2019
Messages
348
Reaction score
300
I used to use Retro-Brite on keyboards. I would remove pickguard from guitar before applying.
 

Nikki M

Member
Joined
Feb 10, 2021
Messages
49
Reaction score
38
seems like the start of Murphy ageing..for a lot le$$..
 

Oranjeaap

Senior Member
Joined
Feb 25, 2010
Messages
9,108
Reaction score
5,154
I thought it said "How to restore yellowed plastic pants"

I guess there are other forums I'd rather take that problem to :laugh2:

seems like the start of Murphy ageing..for a lot le$$..

I wouldn't have bothered if they all were the same stage of yellowing. It's the absurd difference in color between the parts that just looks bad. The guitar itself is pretty mint which only adds to the problem.
 

Oranjeaap

Senior Member
Joined
Feb 25, 2010
Messages
9,108
Reaction score
5,154
Small update.

I tried bleach first. At first no noticable effect but after a few days in a dilluted bleach bath there is some noticable difference.I guess it's about halfway to the desired color. Heading to the store for some H2O2 now, hopefully I get better results.
 

jk60LPTH

Senior Member
Joined
Sep 19, 2019
Messages
348
Reaction score
300

Retrobrite, it has hydrogen peroxide in it, but is a gel made specifically for what you want to do. This has been in use for many decades, ever since they started using bromine in plastics as a fire retardant- once you understand what the problem is, there are many different ways to correct it.

If you don't want to buy Retrobrite, you can make your own, use a salon product like Rockstar already told you, and don't really need to buy a UV light if you have bright sunny days where you live.

You also need a stronger concentration hydrogen peroxide than you can buy in a drug store/pharmacy.

How to fix yellowed plastics on old computers!

Adventures in RetroBright - New techniques for restoring yellowed plastics

The second youtube shows that if you have a way to heat the hydrogen peroxide to 150-160 degrees for 4 hours it is as effective as UV light. Ozone gas is also effective.
 

Oranjeaap

Senior Member
Joined
Feb 25, 2010
Messages
9,108
Reaction score
5,154
Some interesting information there!

My H2O2 isn't very potent, it's just some grocery store stuff. Two days in sunlight didn't really have effect.

Next step was H2O2 + heat. I tried 150F and this had a noticable effect! It did however also have a noticable effect on the shape and dimension of the plastic parts. Back to browsing the internet to find matching parts I guess
 

Latest Threads



Top