I have used S100 "engine brightener" It works well to restore the black to any oxidised black plastic parts. I bought it to restore the black on the switches on my motorcycles. Works very well. If you wash the parts in a strong detergent e.g. Simple green, you will remove the brightener, but a respray will get you back to black. Buy it at your local m/c shop.
Tony Taylor Manchester, NH
To: Classic Rendezvous <firstname.lastname@example.org>; Hugh Thornton <email@example.com> Sent: Mon, January 31, 2011 9:22:22 AM Subject: Re: [CR] Simplex "Plastic" Derailleurs - Questions For Material Scientists
I recently posted a similar request for info regarding salvaging and/or restoring Simplex "plastic" derailleurs on another bike forum and received responses ranging from Mother's "Back to Black" to lighter fluid, followed by a match, a hammer, a heavy boot, etc. Clearly a contentious issue. One member suggested the white bloom was caused by off-gassing as the Delrin gives up its volatile ingredients to atmospheric aging, but that's strictly a guess I would think. Vaseline petroleum jelly was suggested too, reputedly an old car detailer's trick. I decided I will try the Mother's product on my Criterium derailleurs though I admit the Jimi Hendrix approach was tempting.
> From: Hugh Thornton <firstname.lastname@example.org>
> Subject: [CR] Simplex "Plastic" Derailleurs - Questions For Material Scientists
> To: "Classic Rendezvous" <email@example.com>
> Date: Monday, January 31, 2011, 9:02 AM
> The plastic in Simplex derailleurs is
> often referred to as Delrin (A Dupont acetal copolymer).
> As far as I can remember back in the early 1960s, when they
> first appeared, the publicity material referred to Delrin by
> name and the name has been associated ever since. Does
> anybody know whether Simplex continued to use Delrin or
> whether they changed to another acetal or something else
> Another thing I am interested in is the deterioration of
> the finish and whether it is reversible. Occasionally
> early models in white resin come on the market but very
> yellowed. I have wondered whether that is through
> absorption of oil. grease and dirt into the material such
> that it is effectively permanent discoloration, or whether
> it is on the surface and can be
> The common finish deterioration on the black plastic
> moldings of later derailleurs is a blooming or whitening of
> the finish. I assume this is caused by atmospheric
> pollution or exposure to light. This does appear only to
> be "skin deep" and it can be removed rather laboriously with
> a mildly abrasive liquid such as car paint renovator. Does
> anybody know if there is a better way, such as using some
> not too noxious chemicals, that would make it easier to
> renovate, especially in the nooks and crannies which are
> hard to reach any other way?
> You might well ask why anybody would want to renovate a
> Simplex derailleur when it is so much easier to throw it
> away, but the better models such as the LJ 4000, referenced
> recently by a listmember, are not so plentiful. The others
> seem to be considered so plentiful and so disposable that a
> world shortage of them could develop too.
> Hugh Thornton
> Cheshire, England