Why is silicone caulk unpopular?

[LHaven]

First off, I understand that it shouldn't be used for roof applications, and I understand that it's not paintable (which is typically not an RV issue anyway). I'm just wondering about using it in small spot applications, such as the "eyebrow" over a clearance or landing light, which is a plastic to filon joint. The factory seems to have used tan Dicor, and I just think clear silicone out of a hand squeeze tube would be easier to work with and look better.

[notanlines]

Yellows badly with age, when you ‘finger’ it out the clean up is hard, the sun is hard on the caulking, I could go on.

[NH_Bulldog]

Plus silicone can’t stick to itself so if you used it, it better last a lifetime because you will never get it to stick again. Geocel ProFlex is STRONGLY recommended instead.

[rhagfo]

Personally I don’t have an issue with silicone. Never saw the doesn’t stick to its self.

[chuckster57]

Originally Posted by rhagfo

Personally I don’t have an issue with silicone. Never saw the doesn’t stick to its self.

Yup! I see it used on lots of RV’s by lots of different manufacturers. On the roof-no. Around windows and clearance lights-yes.

[notanlines]

If you’re in a business-associated environment you find out quickly that also nothing useful sticks to it.

[chuckster57]

Originally Posted by notanlines

If you’re in a business-associated environment you find out quickly that also nothing useful stocks to it.

I have seen it glue plastic door jamb to the wood frame. And it was a PITA to get it off when I had to “adjust” the frame so the door would close. Mostly bathroom doors on lower priced units.

[Badbart56]

Originally Posted by chuckster57

Yup! I see it used on lots of RV’s by lots of different manufacturers. On the roof-no. Around windows and clearance lights-yes.

More and more silicone lifetime roofs going on. Even Dicor makes a silicone roof system now. And yes, it will stick to itself. You just need to use the primer that's made for it.

[LHaven]

Upon closer examination today, what I thought was tan Dicor was actually dirty silicone. So I cleaned and softened it with mineral spirits, and between my fingers and an old credit card, it all came off the filon and the plastic lens cleanly. So when I reassembled the clearance lights, I just did the job with clear silicone again.

[hankpage]

Another drawback to silicone is if you are sealing an area that contains electrical or metal components the gasses created by curing silicone caulk is corrosive. Make sure the weep-hole on lens covers are clear or bulb contacts MAY corrode and do not use on junction box covers. JM2¢, Hank

[Pmedic4]

Originally Posted by notanlines

If you’re in a business-associated environment you find out quickly that also nothing useful sticks to it.

In the general construction, silicone is the go-to sealer, adhesive, because it sticks to about everything, and it has good flexibility. It is often the product of choice for tubs, sinks, showers, countertops, tile, windows, and doors.

One of the negative issues is that if you get silicone on something, and don't clean it off right away, it sticks forever, as there is no solvent to remove it from any surfaces. The other big issue is that silicone caulks don't accept paint, but they do make paintable silicone. Better for painting are the latex acrylic blends, but latex/acrylic caulk fails if exposed to bright sunlight, so not a good choice for longterm outside exposure. For roofing work, use butyl caulks, which I think is probably what the Dicor and comparable products are for RV roofs too.

For current RV's, if you look around your light fixtures, you'll probably see where they sealed them with a clear silicone based product, and one thing I noticed when I cleaned my RV this year, is dirt gets embedded in the caulk, so you see a small ring around the fixtures where they wiped the caulk around the fixture. Seems like cleaning that caulk off completely may create some leaks around those light fixtures.

[Brantel]

My 2021 Cougar has had some kind factory applied clear sealer which looks and feels like silicone applied to just about every edge of anything that touches the sidewalls and slide boxes. Lights, speakers, windows, handles, edge trim, moldings, gutters, etc. Basically everything....

[Topglock]

When we took delivery of our Bullet in 2015 the dealer used silicone all over except the roof. When I ask what they used he said just regular GE clear silicone. I’ve been using it the last 5 years for touch ups as needed.

[LHaven]

Originally Posted by Pmedic4

The other big issue is that silicone caulks don't accept paint, but they do make paintable silicone. Better for painting are the latex acrylic blends, but latex/acrylic caulk fails if exposed to bright sunlight, so not a good choice for longterm outside exposure.

Aaargh. I'm in fierce sun country. I wish I had known that when DW called me from the hardware store asking if she should get the small plain silicone caulk tube or the larger, paintable silicone caulk tube that was actually cheaper than the small one. Made a bad call there... Ah well, it's not like I won't be re-caulking stuff every year anyway, and now I know.

[Casemaker]

From 40 years in construction industry silicone does not stick to ABS. This main compound used in shower surrounds including shower bases. Don't understand why meg's still use this when installing showers in campers. They will all leak. Brand new Premier 30RI with corner shower leaked on first shower at campsite. Had to tear out whole shower door system and recaulk. >Keystone could care less.

[Tom N OH]

I’d hate to guess how many times I’ve peeled off silicone to find water under/behind it, along with water damage from an obvious long-term leak. The only thing I’ve found it to be even halfway good at is automotive gasket applications & only then if you actually allow the silicone to “skin” slightly before assembly as the instructions say. If you slap things together before the silicone has a chance to skin, it’s almost guaranteed to leak.

[Bill-2020]

Originally Posted by Pmedic4

One of the negative issues is that if you get silicone on something, and don't clean it off right away, it sticks forever, as there is no solvent to remove it from any surfaces.

Yes, there is. I use it, personally and professionally. DSR-5 Not cheap by any stretch, but it does remove uncured and cured silicone and every other adhesive I've tried it on. For cured stuff, remove what you can, then soak the area with DSR-5, let it do its thing and it'll work its way under the silicone and it will release it from filon, aluminum, plastics, and most other non-porous surfaces. Remove the wet DSR-5 with IPA 50-70%. Then rinse with clean water/wet rag.

[JRTJH]

Bill,

Do you have any information on how DSR-5 affects TPO or EPDM roofing?

[Bill-2020]

Originally Posted by JRTJH

Bill,

Do you have any information on how DSR-5 affects TPO or EPDM roofing?

No I sure don't, but I' can post a picture of the label and cautions. Stand by... I happen to be at work (where the DSR-5 is) on a network data transfer task that'll take me the weekend to finish... not that I intend on being here the WHOLE time...

[Bill-2020]

No details on the jug about surfaces it shouldn't be used on. Maybe something online...