I read some material which was against the use of silicon based products and decided to look into it, as I was always a bit suspect about exterior rubber material that had been treated with silicon protectant in the past, thinking that it might have accelerated degradation. Has anyone read the essay by car care specialties Larry Reynolds on their website (and a similar rant by the same author found upon the BMW FAQ digest, section 5.3-5.4) which suggests that silicon based "protectants" on the market might do more harm than good on rubber & vinyl - especially on tyres and, in some cases (formaldehyde content), vinyl dashes.

He states such things as:
"The raw silicon oil that is the main ingredient in most of the nationally advertised over the counter products may actually dissolve the wax and be the cause of premature sidewall cracking/failure." (Car Care specialties Inc. website, "Tires, Rubber and Vinyl" 1999)
"Silicone oil may also dissolve  the essential oils in the vinyl skin, hastening the premature formation of cracks in the vinyl skin. A quality vinyl protectant will contain a UV protectant and essential oils to replace lost oils from the vinyl. These protectants are expensive, so the K-Mart specials may do more harm than good." (BMW FAQ digest 5.3)

I asked Armor All about claims that silicon was damaging and they responded:

Thank you for contacting us about ARMOR ALL Protectant. We appreciate your interest in our product.

ARMOR ALL Protectant is a water based silicone emulsion specifically designed to protect and beautify polymeric materials such as rubber, plastic, vinyl. The protectant fights deterioration caused by ozone, oxidation and ultra-violet radiation.

We have done extensive testing to ensure that our product is safe for recommended surfaces. Specifically, we have tests supporting the benefits of ARMOR ALL Protectant per the American Society of Testing Materials (ASTM) procedure G-25, which is also described in AATCC Method 16A-1971. We have also done tests which conclusively prove the benefits of ARMOR ALL Protectant in extending the life of tires and other automotive materials.

While we are confident that ARMOR ALL Protectant is both safe and effective, we are also aware that nothing can prevent the eventual failure of polymeric materials. Deterioration of these materials can start within one to three years. The rate of this deterioration is dependent upon many factors, including exposure to the elements, the amount of care given to the surface, and the original quality of the material.

I hope this information answers your concerns and that you will continue to use ARMOR ALL Protectant with confidence. Again, thank you for contacting us.

OK, so this response was basically the opposite to what Reynolds was saying. I have sent emails to Reynolds a number of times asking for clarification, and also to explain why he says silicon is not good and yet recommends Meguiars #40. Both Meguiars products M40 and G41 (the product which supersedes M40) contain polysiloxane, according to the materials safety data sheet published by that company. I also sent Reynolds a little .gif picture of the polysiloxane molecule with the silicon sitting right there in the molecular configuration.

Unfortunately I am still in the dark as I have not heard anything from Reynolds or anyone at Car Care Specialties. As I mentioned I am intuitively inclined to believe him - maybe a bit like Fox Mulder - that silicon products can harm exterior rubber work... but there seems to be little to substantiate that, besides what Reynolds says. Can anyone shine some light on the subject?
 

There is a second element to this discussion - why do the roof strips on some 850s degrade? There was a post on brickboard a while back saying that nobody seemed to know - or that might have been Kino's site. Could chemical aggression due to polishes/protectants, or specific substances such as silicon or formaldehyde be causing this? Does anyone know what material the roof strip coating is made of, and/or how it adheres to the metal strip itself? Calling all chemical engineers...
 

Gaday,
I worked for Dow-Corning for 8 years in a past life and have some info you might be interested in. "Armor-All" is a mixture of water, about 200ppm of UV blocker materials and what Dow calls "Code-AX"  Code-AX is indeed a siloxane compound that is primarily polysiloxane linears. Linears are what give it a sliding or slick feel and consistancy.  The bound water is what gives it the shine. However, this material can and will chemisorb plasticizers from rubber based materials.
I won't let the stuff near my 2 Volvo 850's
No name/no lawsuit

... posted by Michael from Sydney  on Wednesday, 21 February 2001, at 10:23 p.m.
 

                      Hi all,

                      There are a few essays on the web that state that silicon based products are really bad for certain parts
                      of your car. These are by Larry Reynolds and appear on the BMW FAQ digest and the Car Care
                      specialties Inc. website. I have done my best to find out what the story is with silicon based materials
                      used as protectants and their involvement in the degradation of exterior rubber and vinyl dashes. Alas I
                      have run into a dead end.

                      I hope somebody out there can help.

                      I have summarised the position on my website page as it is a little lengthy to post here. I sent an email to
                      armor all, and obtained material safety data sheets from Meguiars. There were no answers forthcoming
                      from Larry Reynolds despite email requests to clarify.

                      Has anybody else got the feeling that silicon based products could be a problem for common materials
                      usedon cars, or maybe anecdotal evidence? I wonder whether the roof strips that so often peel on 850s
                      might also be responding to an attack by some protectant or polish?

                      --
                      Michael from Sydney

... posted by michael in Sydney  on Friday, 23 February 2001, at 5:52 a.m. ...in response to
                      "The mystery of rubber-vinyl degradation (inc. roof strips?) and so-called "protectants"" posted
                      by Michael from Sydney.

                      This is kinda like playing solitaire in a casino, but I'll answer my own post since it looks lonely here. I did
                      receive a response by email from an anonymous source who worked right in the thick of the relevant
                      industries and stated, with reference to siloxanes, that "this material can and will chemisorb plasticizers
                      from rubber based materials. I won't let the stuff near my Volvo 850's".

                      As mentioned before, the Material Safety Data Sheets sent to me by Meguiars list the Meguiars #40 &
                      Natural shine 41 as containing polysiloxanes. The phantom emailer also indicated the best thing to do
                      was just use a bit of soap & warm water, thus allowing the complex balance of plasticiser in vinyl to
                      remain as its maker intended.

                      Does anyone want to buy 3 x 500ml bottles of armour all and an almost full bottle of Meguiars #40?
                      Maybe trade for Lexol, black again or Amsoil ATF?

                      --
                      Michael in Sydney

Michael - FWIW I noticed the (rubber/vinyl) roof strips coming unglued on my
'97 T5 several months ago, and they've never had armor all or any other
substance except soap and water on them. I simply epoxied them back down to
the underlying trim (yes, it took a while!). no further problems thus far.

                      Hi Gary,

                      Was the outer black coating of the strips also degrading or was it just the trim separating?
                      I am interested in this from a preventative side as I haven't had any probs with mine, but I did see an
                      850 in a dealer's yard with the black outer coating mostly off, with just bare metal strip underneath.
                      Looked awful.
                    Kino's website survey 2 showed that owners complained that the strips or faulty drip rail moldings "tend
                      to peel and crack".
                      I am worried that the silicon products might do this to the outer/top black coating.

                      Thanks
                      Michael

Michael - In re-reading what I wrote, it's apparent I didn't explain myself
very well... the outer black coating was peeling off. As I recall, on both
sides, the coating was coming loose from the metal trim for almost the full
length of the roof, on the outside edges. I simply re-glued the coating to the
trim. As I think about this, it may have started coming unglued on it's own,
then a few trips to the high pressure car wash (handheld wand type) would have
"unzipped" it quite nicely.

                      Thanks Gary,

                      So it looks like the silicon protectants are not necessarily implicated in the roof strip peeling - at least not
                      in the case of peel alone. Sounds like "peel" and "crack" are different things. Thanks for the info.

Michael - Another possibility that has crossed my mind... I have to wonder if
this is another case of an "environmentally friendly" adhesive not doing it's
job very well: I guess we'll know in another 3 or 4 years, since I used no
such animal when I re-glued the vinyl!

> Hi Michael;
>
> I came across your interesting thread about Armor All type
> products while gathering info for the tech forum
> on our Fiat enthusiasts website. <http://www.mirafiori.com>
>
> I asked one of our members who is a chemical engineer
> in the plastics business for many years about the comment made by
> the anonymous former Dow Corning chemist. His reply follows:
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>
> I did a little checking with a colleague (PhD Chemist) to see
> what he thinks. Our take on it is this:
>
> chemisorbtion is the formation of bonds between surface
> molecules of usually a metal, and another substance in contact
> with it. Solids with high surface energies are necessary for
> chemisorption to occur, e.g. nickel, silver, platinum, etc.
> these are the basis of catalysts. I don't think this can take
> place on a vinyl dash. The conclusion here is that the term was
> misused.
> Siloxanes are straight chain compounds of Si single bonded to O
> atoms. This is what keeps the water bonded. Although it might
> be possible for these compounds to bond to plasticizers, one
> must weigh the relative good vs evil. Not treating a dash with
> anything is likely much worse than the moderate use of such
> products. The UV inhibitor for example is critical in the
> preservation of vinyl and rubber products. Also silicones are
> advantagous to protect from weathering and attack from Ozone.
> The use of silicone on rubber gaskets and seals is a widely
> accepted practice and I'm convinced it works. I tend to keep
> cars a long time and have long term experience with a car not
> treated and one that was. It was our conclusion that
> a "protective" layer of silicone is more beneficial than no
> protection at all and out weighs any possible detrimental
> effects of the use of such products.
>
> I hope this helps. Remember, this was free, so take it for what
> it's worth.
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> - -
>
> It would be interesting to hear from more professionals from
> industry. This is an interesting topic!
>
> Cheers
>
> John Goodfellow
> Long Island, NY

Dear John,

Thank you very much for your information. I shall be sure to post it on  my website with the rest of the thread that you have already  encountered (I think that we're both talking about url  <http://au.oocities.com/ozbrick850/silicon4rubber-vinyl.html> ).  Your chemist may be right, but I wonder whether the process of  accelerated ageing of plastic products (observed by some to be  correlated with silicon based products) may be due to something that occurs not specifically because of the Si-O molecules but may be due to something else contingent, e.g. a process of degradation that occurs after the silicon product has worn off, or whether some other carrier  in the product is causing the damage (or both?). Also, there would be  no doubt that UV protection is a good thing, but could that be  accomplished with a more inert substance?  I must say that I am still a little worried about using silicon based  products on my cars, but I believe that every little bit of information  and opinion is useful in making a decision, and that the jury is still  out. Funny, I had just been thinking about submitting the question to  the BMW forums as I have been intending to do for a while now. Perhaps  that will be something to put energy into soon, and I will copy you  with any results of asking that forum.
Happy motoring & thanks again
Michael @ Sydney / OzBrick
 

Ozbrick: Well, thats it for the moment, and as I stated I'll stir the waters at the BMW forums next, so check back here for
more on "the mystery of rubber-vinyl degradation" which still remains a mystery...