How common is silicone caulk usage by manufacturers?

ernie1 wrote:
ktmrfs,
Thanks for your very complete response and, believe it or not, I understand most of it and it makes sense. But, not to belabor the point, how do i know what is the proper and/or best silicone product to get? Apparently one can't rely totally on the claims on the packaging.
Years ago I assembled major parts of the engine to my Corvette with Permatex silicone which made claims on the packaging that it will work for my particular application. After about 2-3 months, all surfaces that had silicone failed as the oil and gasoline ate through it. Yet at the same time, GM was selling their own brand of expensive silicone for this application and that product worked and did not fail. So how does one know?

I would suggest you find a dealer that does restorations on boats and ask him. Or contact GE or Dow Corning directly for their opinion.

ktmrfs,
Thanks for your very complete response and, believe it or not, I understand most of it and it makes sense. But, not to belabor the point, how do i know what is the proper and/or best silicone product to get? Apparently one can't rely totally on the claims on the packaging.
Years ago I assembled major parts of the engine to my Corvette with Permatex silicone which made claims on the packaging that it will work for my particular application. After about 2-3 months, all surfaces that had silicone failed as the oil and gasoline ate through it. Yet at the same time, GM was selling their own brand of expensive silicone for this application and that product worked and did not fail. So how does one know?

What is the difference ???
The only good stuff is for use below waterline.
It is the same as the one made for Aquariums
same as "Marine Silicone"
same stuff that takes your breath if you inhale it.
the same stuff that you don't ever want to use for installing a window, because you will never get it back out.
Yes, there is a big difference in 100% silicone !

westend wrote:
Silicone is an excellent sealant between two surfaces held in compression. It doesn't tolerate sunlight, weather, or movement very well.

Agree. I use silicone only to seal mounted fixtures that may need to be removed, as a gasket, if you will. I prefer quality marine polyurethanes for permanent aluminum and fiberglass installations and joint sealing. I've had good results with Dicor on the rubber roof and Eternabond or similar "tapes" for rips.

OP may want to contact GE for some of their products. An rv manufacturer is not likely to spend ten dollars per tube for a sealant. What do you suppose is used to join glass panels in aquariums? Silicone. Previous poster is correct.

ernie1 wrote:
So if all silicones are not the same, what is the difference in all the "100% Silicone" products on the market? Do some have impurities or are some of the silicone materials different from others and have different properties? Other than price and claims by the manufacturers, how do you know?

silcones can be made to cure in multiple ways, some give off acetic acid when curing, others cure by other means. And silicone is NOT an element, it is a chemical compound that can have multiple formulations and designed with different adhesive properties, different UV properties and different resistance to chemicals.

Silicones are polymers that include silicon together with carbon, hydrogen, oxygen, and sometimes other elements. Some common forms include silicone oil, silicone grease, silicone rubber, silicone resin, and silicone caulk.

"More precisely called polymerized siloxanes or polysiloxanes, silicones are mixed inorganic-organic polymers with the chemical formula R2SiOn, where R is an organic group such as methyl, ethyl, or phenyl. These materials consist of an inorganic silicon-oxygen backbone (?-Si-O-Si-O-Si-O-?) with organic side groups attached to the silicon atoms, which are four-coordinate."

Do NOT confuse silicones with the element silicon. Silicones do contain silicon (Si) but that's about it.

The 100% silicone sealant is just as much 100% silicone as is the silicone grease, silicone dielectric compound, silicone sheet material etc. that is also available.

Often times mfg offer a range of silicone and non silicone sealants/adhesives for the same applications, you can pick and choose what you think will work best for your application.

IMHO there are mfg that over the years have developed a reputation for adhesives for different markets with great success. Look at their offerings compared to what you are looking for. 3M and GE are two such companies, They have a wide variety of silicones with for use in many different applications.

when used for the application they are designed for and applied as directed they can work very well.

conversely, using the wrong formulation for the application or not following application directions can end up as a real mess.

And often times that tube of silicone from the hardware store is not a good choice for outside RV applications.

Likewise a UV cure silicone is not likely a good solution for inside use!

So if all silicones are not the same, what is the difference in all the "100% Silicone" products on the market? Do some have impurities or are some of the silicone materials different from others and have different properties? Other than price and claims by the manufacturers, how do you know?

Well niner, I see you still have a sharp stick to poke me with. You are right, I will be running my 2000i in wally world this winter. i will let you know where i am over nighting so you can see if you can hear it above all the teens meeting there with no mufflers on their beaters or the reefers firing up at random times. :B

And as you can see from other posts silicon does have a place. I did not mention that I only use the quality stuff on my RV. I also know about the dicor self leveling and non self leveling and use it also as appropriate.

You have a nice day and watch that blood pressure.

Silicone is an excellent sealant between two surfaces held in compression. It doesn't tolerate sunlight, weather, or movement very well. IMO, it really has no place in RV construction. The polymer sealants like Proflex and Dicor are superior to silicone in every aspect.

The 3M silicone caulk remover works well, especially if allowed to work for a period of time. After mechanically removing the old silicone caulk, there will be some silicone residue on the surface. That can be removed with a solvent prior to resealing the joint with different caulk.