19 replies to this topic

[janj86]

You fellows have been great help in past. I have a new question - how to "de-yellow" Lexan, i.e. make originally clear windscreens be clear again.

[Horsepower]

To my knowledge it can't be done. The only recourse is buy a new body or copy the old one.

[Bill from NH]

I don't remember old Lexan yellowing, but butyrate will.

[Cheater]

J.J.,

I'm with Bill, I think what you have is yellowed butyrate, not Lexan. And there really is no way to "clean" it primarily because it isn't dirty.

The yellowing you see is actually a chemical change in the base material itself and if there's a method to reverse that change to make the butyrate clear again, no one has yet discovered it.

[Hworth08]

Rick (dc-65x) had pretty good success "de-yellowing" a body a year or two ago but I don't remember the specific thread.

[dc-65x]

Hi Don,

Here's the thread you may be thinking of:

A Tale of two Harveys

I cleaned and polished the scratches out of two old butyrate bodies. I haven't found a way to remove the yellowing. As Cheater said, it seems to go all the way through the material.

[Noose]

I haven't found any way to get rid of the yellowing on those old butyrate bodies.

[TSR]

There is no way because it is not in surface but through the whole thickness of the material when it happens.

Many younger slot racers do not understand the difference between Polystyrene Butyrate (the old stuff) and the Lexan Polycarbonate, so any old bodies are dubbed to be "Lexan" because that's all they have ever known.

And of course Polycarbonate does not yellow like the old stuff...

[penske]

I'm just wondering if the stuff they sell now for removing scratches and "yellowing" from car headlights would work. I used it on my '97 Honda and it did a very good job.

Roger

[Cheater]

Roger,

It's doubtful, due to the discoloration being throughout the butyrate and not simply a surface layer that can be polished away.

But, hey, if you have a yellowed body and some remaining polish give it a try and report back.

[Jacob Shiplet]

Roger,

Your headlight is only yellowed on the surface and normally only the protective film on the headlight itself. If the headlight has been sandblasted too much and the protective coating is gone, the buff job is not going to do your headlight any good. I have polished/tried to polish several hundred headlights in my day, and I could tell after awhile which ones could be saved and which ones couldn't.

I am not sure what the protective coatings are on the headlights, but it seems whatever Chrysler uses sucks. Most of what I couldn't save came from them.

[Mark H]

I would just leave it yellowed, it gives it character and you know it's actually old and not a repro.

But that's just me.

[Horsepower]

Or just paint it yellow with a stripe and the yellow windows will look tinted.

[ShootinSparks]

J.J., if you paint it black or a dark color, it is doubtful that the yellowing will show except on the "glass" areas, and you could mitigate that somewhat by tinting those areas with a few light coats of transparent blue.

[Bill from NH]

Yellow + blue = green.

[Don Wedding]

I have worked at the plant that makes Lexan For the last 35 years. The early Lexan film was produced with very little UV stabilizer, that is where the yellowing comes from. Just age will yellow the old Lexan.

The new formulation has all kinds of exotic age inhibitors and UV blockers. Plus we use less benzene in the process and a cleaner BPA additive.

I have worked a lot with trying to get the yellow out of the old Lexan bodies and you only will weaken and cause crazing or cracks if you try any harsh chemicals. We only recommend using a mild soap with warm water to clean the old bodies.

[Red Car Driver]

Some one said hydrogen peroxide will help in another thread, but I haven't tried it because I think it will make the plastic crack easier.

Yellow + blue only = green in additive color mixing, e.g. paint. Yellow + blue when mixing light, as in color photography, makes for a more neutral yellowish color moving towards grey.

[janj86]

Thanks, guys. :-)

[Ramcatlarry]

I have a hunch that the final 'polish' for the headlamps is only 'future floor wax' - a clear acrylic coat that does work well over decals, also.