EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: madshaman on October 10, 2013, 07:15:35 pm
-
Hi everyone, I've heard there are some "magical" solutions for de-yellowing that range of white->beige plastic that was used for chassis and controls in the 70s and 80s.
Anyone have experience doing this themselves and anyone have a sure-fire technique.
Any info is welcome from how to determine the type of plastic and how to go about de-yellowing it.
-
It's usually the bromine they use as a fire retardant. You can generally clean it with hydrogen peroxide.
-
This link might be of interest:
http://68kmla.org/forums/viewtopic.php?p=93761 (http://68kmla.org/forums/viewtopic.php?p=93761)
-
I tried this out today: http://retr0bright.wikispaces.com/Retr0Bright+Gel (http://retr0bright.wikispaces.com/Retr0Bright+Gel)
Glad to say it works even with fluorescent light. I used 6% hydrogen peroxide, cheap version of oxi-action and corn starch. After two hours, great difference, but UV light would be good for anything more than light yellowing.
-
I tried this out today: http://retr0bright.wikispaces.com/Retr0Bright+Gel (http://retr0bright.wikispaces.com/Retr0Bright+Gel)
Glad to say it works even with fluorescent light. I used 6% hydrogen peroxide, cheap version of oxi-action and corn starch. After two hours, great difference, but UV light would be good for anything more than light yellowing.
I've tried it on a Commodore Amiga 1200 and it works perfectly. :-+
-
Brilliant guys, thanks for the great info including the bromine hint!
-
Works great, do make the gel, its way better than the liquid. If you let the mixture go too long you will "scorch" the plastic edges and they'll have crusty white artifacts. Once you see this barely starting to occur pull it out and clean it off.
Also, your plastics will re-yellow AGAIN UNLESS you clearcoat with UV protectant. The cycle will just repeat itself, but faster this time. Nobody remembers to do this because it can take 2-3 years but it will be worse than it was before.
-
Thought I'd resurrect this thread because I'm doing a plastic restoration right now. The patient is a GW Instek GDM-8251A. First pics are the initial conditions of the plastic. As you can see it's pretty yellowed where the rubber boot didn't cover it. The white area where the button labels are, is not the same plastic, it's covered by a sticker. If you look around the edges you can see where the rubber boot didn't quite cover the white plastic.
Also, the gray handle is yellowed also, so will do the same treatment to that as well.
What I'll be using, which has proven to work very well many times, is a gel-like peroxide you can get at hair salon supply shops, shown below. I'll put up more pics as I get it prepared ...
-
What I'll be using, which has proven to work very well many times, is a gel-like peroxide you can get at hair salon supply shops, shown below. I'll put up more pics as I get it prepared ...
A word of caution regarding hair salon products: some of them also contain phosphoric acid in unknown concentrations. Not a big deal most of the time since the concentration should be low, but phosphoric acid does not interact well with certain types of plastics. Beware if you plan to soak your plastics for extended periods of time.
Also, your plastics will re-yellow AGAIN UNLESS you clearcoat with UV protectant. The cycle will just repeat itself, but faster this time. Nobody remembers to do this because it can take 2-3 years but it will be worse than it was before.
It's not even clear that the bromine re-surfacing is due to UV. I've heard reports that the plastics will re-yellow even when stored in the dark.
-
A word of caution regarding hair salon products: some of them also contain phosphoric acid in unknown concentrations. Not a big deal most of the time since the concentration should be low, but phosphoric acid does not interact well with certain types of plastics. Beware if you plan to soak your plastics for extended periods of time.
Never had a problem using it here yet, but all these home remedies come with the same disclaimer -
"Use at your own risk" :)
Got the meter faceplate prepared. Need to remove everything because your going to have a gooey mess on it and will need to be washed off. Brush on the peroxide and cover with saran wrap so it doesn't dry up in the sun. Then place out in the sun for a few hours and check on it. Preferably next to a ceramic frog. :-+
-
Are you gonna try to clean the boots? I would like to see how that goes also. They appear to be TPE plastic, I got some hits on google from sex doll forums, same material apparantly.
-
Are you gonna try to clean the boots? I would like to see how that goes also. They appear to be TPE plastic, I got some hits on google from sex doll forums, same material apparantly.
The rubber boots? When I got the meter I washed them in warm soapy water. That's all I see that they need.
But I checked on the plastic - :-+ Lookin' great! Will update later today or tomorrow but the process is working as planned. :clap:
-
Musical comment on above (or below) previous
https://www.youtube.com/watch?v=LSniBxXjK_8 (https://www.youtube.com/watch?v=LSniBxXjK_8)
"I blew up her body, but she blew my mind"
-
Just last week I fixed up a yellowed Keithley 2400 front panel using this technique. Worked like a charm. This was not my first time. I've done maybe 10 front panels of various gear now. I use "40 vol" (very high strength) gelled hair 'bleach' (peroxide). I do not add anything such as oxy clean (some say this is a needed activator, not in my experience).
Here's what I do:
- put on eye protection and a pair of Nitrile gloves. Or two pair, even better. You do not want this stuff getting onto your skin or eyes. It is strong enough to badly burn.
- wash the part very well with soap and water then rinse and dry. Oily surface will prevent the water-based peroxide from working.
- Paint the gel onto the surface of the plastic, trying to keep it on the problem areas (i.e. avoid display lens, etc.)
- place part into a glass or ceramic dish with high enough lip to clear the item.
- cover with one layer of plastic food wrap to prevent evaporation.
- place in full mid-day sun
- rotate every 5 minutes to get even UV exposure.
- After literally only 20 to 30 minutes (for light/moderate yellowing) in the sun, the job is done. It should not take hours and hours. If it does, you have ineffective chemicals, so find something better. For very deeply yellowed stuff, re-apply gel every 20 minutes, and don't expect a miracle, it may never get there.
- Rinse extremely well under running tap water for several minutes. Use a brush to ensure you get into all the nooks and crannies.
- Blow dry with compressed air - the gel won't blow off as easily as water so you will see if you missed some.
I have found that the silkscreen on the Keithley stuff is not harmed after just 20 minutes. However, when experimenting with materials and methods years ago, I did have one soaking for many hours, and when I rinsed it, the silkscreen ink had softened enough to rub off under my fingers. D'oh. Be careful.
-
[...]
- Rinse extremely well under running tap water for several minutes. Use a brush to ensure you get into all the nooks and crannies.
- Blow dry with compressed air - the gel won't blow off as easily as water so you will see if you missed some.
[...]
Thank you, macboy; great instructions. I would add one comment:
For the above two steps, wear safety goggles!
You don't want little droplets of hydrogen peroxide reaching your eyes...
-
Complete success! :clap:
-
[...]
- Rinse extremely well under running tap water for several minutes. Use a brush to ensure you get into all the nooks and crannies.
- Blow dry with compressed air - the gel won't blow off as easily as water so you will see if you missed some.
[...]
Thank you, macboy; great instructions. I would add one comment:
For the above two steps, wear safety goggles!
You don't want little droplets of hydrogen peroxide reaching your eyes...
Good point, edited my post.
-
After I clean the plastic I rub Armor All on it. Makes it look new plus it has a UV inhibitor in it. And by the way, if you have Armor All in a white plastic bottle and you can't see the liquid, you do have to shake it up. It settles out - see pic.