Originally Posted by Jeff61
No, but one of the things, I did do was take a towel, apply some baby powder and wipe down the seals. That little bit of dust on them really keeps the sticking down when you reopen it
This is an excellent point...any powder-ish material can keep the seal from sticking, acting as a lower-friction barrier. Powder will not do anything for the seal itself, will not protect it from UV light (if it needs it)
My question about cornstarch relates to the fact that it is an organic material than can lodge in pores in the seal, attract moisture, break down, mold, and other non-fun things. A non-organic, like a talc-based powder, would probably be a better choice if you want to go down the powder road.
Does it really matter? EDPM is tough stuff, so it’s hard to say. A lot can depend on the actual material, temperature, humidity, dust, atmospheric contaminants….but in general, I'd stay away from organics and petroleum and silicones, but that is me.
Like many things, it gets complicated when you get to the details.
The 303 folks have this to say:
Rubber Seals - Not `Rubber' Anymore
Maybe not a surprise, but no longer are a car's rubber seals made from `rubber'. To keep the inside of your car quiet and dry, car makers use a specialized synthetic material called EPDM, (ethylene propylene diene monomer).
Real rubber, or blends containing real rubber, just cannot endure the direct exposure to sunlight(ultraviolet light) and the harmful-to-rubber oxidizing gases in our atmosphere (see Tech Facts Vol. 1). To quote from the engineering specs, EPDM is "Ideal for outdoor applications because of its excellent resistance to ultraviolet light, ozone, oxidants, and severe weather conditions".
EPDM is great stuff, but it has some downsides. It's tear resistance is only fair, so sticking & tearing is not uncommon. And just like real rubber, it has extremely poor resistance to solvents (petroleum distillates) and oils.
"You mean I don't have to `protect' my car's door & trunk seals?"
That's right, and treating your seals with a leading-brand "protectant" is almost always exactly the WRONG thing to do to your seals. Any chemical product that contains oils or petroleum distillates is incompatible with EPDM.
TIP: NEVER apply any rubber or vinyl treatment that has an oily or greasy nature or contains petroleum distillates. READ THE LABEL! If a product contains petroleum distillates, do not apply it to your rubber seals.
Though its powerful UV screening benefit is not needed in this application, 303® Aerospace Protectant™ is great for cleaning EPDM seals and to keep them clean. 303® Aerospace Protectant™ makes EPDM seals look like new and PREVENTS sticking and tearing. Because it is safe for EPDM and prevents sticking & tearing, manufacturers exclusively recommend 303® Aerospace Protectant™ for this application.