hey all,
i was waiting for someone to say my favorite trick for "nourishing" the faded/discolored delrin, and to my surprise no one said tri-flow! i stumbled upon tri-flow's amazing restorative powers while servicing cheap french bikes, lubing the derailleurs as i was making adjustments(man worn out prestige derailleurs...)and the black came back to a deep glossy black when the tri-flow hit the delrin! i've been pouring chain lube all over these plastic parts as they come in the shop since! i think that along with looking great this treatment keeps the parts from being brittle, so less prone to breaking, and lubed and working smoothly.
now the shop i work for has switched to phil wood bio lube, and it brings back the black too, but the result is a little grayer, tri-flow leaves a much better result to my eyes.
i cleaned and restored a set of simplex criterium derailleurs and shifters between three or four years ago. i applied tri-flow to them as i worked, and they have sat on the cool-parts display/storage shelf in my home shop since. this is the most of a test i have to offer, the derailleurs are still super lusterous looking, not wet looking either, they look fresh, i haven't re-applied tri-flow since the first application. they havn't been rain or weather tested, but if i was using them i'd just re-lube as needed.
all that said, i don't have the background to answer a question i've had about the "nourishing" of delrin plastic. john do you know if the teflon or something else in tri-low's makeup is similar to/ shares qualities with delrin? it looks so good i've wondered if there is a connecton.
david"takes maybe too much pleasure in restoring delrin"cox portland oregon usa
Message: 9
> Date: Mon, 31 Jan 2011 13:10:46 -0500
> From: "Jon Crate" <Jon@FAI.US>
> Subject: Re: [CR] Simplex "Plastic" Derailleurs - Questions For
> MaterialScientists
> To: "'Hugh Thornton'" <hughwthornton@yahoo.co.uk>, "'Classic
> Rendezvous'" <classicrendezvous@bikelist.org>
> Message-ID: <39C6A564299B438FAB0D6B5DF8843FA5@qwerty28>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hugh,
> You put one in my wheelhouse.
> The Delrins are actually all polyacetal homopolymer, not copolymers.
> Delrin (and other brands of polyacetal homopolymer) are a very good
> plastic.
> Originally, the only brand was DuPont, but now there are a few Asian
> sources, which I assume are just as good.
> The different grades are primarily based on additive packages, but melt
> flow
> (molecular weights) and coloring are differentiated by grade.
>
> We routinely (every week) verify the identity of incoming Delrin raw
> material lots for an Italian medical device company that makes artificial
> heart valves and stents as well as for their outgoing products.
>
> Differentiating DuPont Delrin from other brands of polyacetal homopolymer
> is
> not easily done as they all look alike for any of the basic tests. However
> a
> simple FT-IR test will tell me if a derailleur body is a polyacetal
> homopolymer (such as Delrin) or another type of plastic.
>
> I recently purchased from our friends at Reperages Velo in France a NOS
> white Delrin long cage SLJ rear derailleur and I will post photos of it for
> you tomorrow. I tend to think the white body version is pretty rare (and
> pretty good looking too).
>
> Jon M. Crate
> FAI Materials Testing Laboratory, Inc.
> 825?Chance Road
> Marietta, Georgia 30066
> http://www.FAI.US
> ?
>
> -----Original Message-----
> From: classicrendezvous-bounces@bikelist.org
> [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of Hugh Thornton
> Sent: Monday, January 31, 2011 9:03 AM
> To: Classic Rendezvous
> Subject: [CR] Simplex "Plastic" Derailleurs - Questions For
> MaterialScientists
>
> 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 altogether?
>
> 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
> removed.
>
> 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