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-   -   Painting over silicone caulk?? (http://www.diychatroom.com/f4/painting-over-silicone-caulk-49960/)

jschack 07-30-2009 08:48 PM

Painting over silicone caulk??
 
My painter accidently used GE silicone II sealant, clear. It is Gutter & Flashing and it says not paintable. What can I do to in order to paint it?? Please help:(

evapman 07-30-2009 10:35 PM

Hi Jschack,

Never had any luck painting over silicone with oil or latex. prolly have to remove it and use paintable caulk. :(

chrisn 07-31-2009 05:44 AM

Quote:

Originally Posted by evapman (Post 308799)
Hi Jschack,

Never had any luck painting over silicone with oil or latex. prolly have to remove it and use paintable caulk. :(

Unfortunatly that is true.

slickracer 07-31-2009 07:09 AM

I've had good luck priming first with Cover Stain and then painting. Has held for 4 years now...

poppameth 07-31-2009 08:04 PM

I second CoverStain. I've also done this on occasion and it does seem to work. BIN also seems to work okay. Those are the only two I've ever tried it with. Neither is a real solution. Both "may or may not" work for you. Actually I had some silicone on the outside of my house filling the hole around the cable tv connection coming in. I painted right over that with P&L SuPrime 100% Acrylic. I just checked it and it's on there tight. Maybe having weathered so long it had more tooth for the primer to grab to. I find it kind of odd that acrylic stuck to it though.

chrisn 08-01-2009 05:16 AM

[quote=poppameth;309171]I second CoverStain. I've also done this on occasion and it does seem to work. BIN also seems to work okay. Those are the only two I've ever tried it with. Neither is a real solution.:no: Both "may or may not" work for you.


I would not bet on either one. Neither one is labled for coverage over silicon and I would bet if slickracer took a fingernail over what he did it would not hold up.

slickracer 08-01-2009 06:51 AM

One thing I did was really clean the caulk with mineral spirits before I primed. Maybe that helped.

chrisn 08-01-2009 06:13 PM

Quote:

Originally Posted by slickracer (Post 309265)
One thing I did was really clean the caulk with mineral spirits before I primed. Maybe that helped.

If it is still sticking then maybe you have found the solution.

ccarlisle 08-01-2009 07:58 PM

In actual fact, that silicone adhesive your friend inadvertently used is a fine example of just how silicones work - well, that is those that are chemically of a certain structure (because not all silicones show adhesive proeprties - but close enough for the sake of this thread).

Silicones like this one attach themselves chemically to the substrate whereas other caulking compounds attach themselves mechanically to the substate. In doing so, silicones can attach themselves to pretty well any substrate much better than other products because they orient themselves in such a way that on one side of the bead (towards the substrate) they stick and on the other side facing you they do the opposite: they repel anything that tries to stick to them...:yes:

Chemical bonding and all that...but on the side facing you, you are looking at a very slick surface that as I said repels everything - much like the wax on the hood of your car...products just bead up once they land on a silicone and fall off. They do that by orienting the silicone molecules in such a way that the surface has very low "surface tension". That means everything rolls off it.

To put it into numbers, the silicone surface has a surafce tension somewhere around 30 dynes/cm...water has a higher surface tension around 72 dynes/cm. Now by physiochemical principles, the higher surface tension product (water) cannot remain comfortably on the lower surface tension product (silicone) - and the water rolls off.

Thus the only way to make something stick to a silicone is to give it the same surface tension as the silicone...don't ask how I know that, I just do. :laughing:

Ta-da... "fluorochemicals" to the rescue!!:thumbsup:

If you put "fluorochemicals" into a caulk or a paint, it would stick to silicones. Some products have "fluorochemicals" in them, but they ain't cheap.

Sooooo...95% of the products you try to put over that type of silicone wan't stick for very long. But one or two just might. Either spend your time trying to find that one or two products, or take it out and do it properly.

Here endeth the lesson...:whistling2: Not bad for a Saturday night :laughing: I gotta get a life...

chrisn 08-02-2009 04:41 AM

Now,THERE is the answer!:thumbsup::thumbup::yes::):laughing:

fstwrtr 08-02-2009 09:21 PM

OR you could simply buy a tube of siliconized latex caulk such as Sherwin Williams 950 and re caulk over the GE stuff, then simply paint over the area..

saggdevil 08-02-2009 11:06 PM

I'd attempt to use "paintable silicone" over the existing silicone caulk; prime the caulked area, then repaint. Before re-caulking, use alcohol or clear water to wipe off the originial caulk and dry completely. I've painted over the paintable silicone with no problems.

Btw...at one time GE caulk was manufactured by Dow Corning (the makers of RTV). That may or may not be the case now. It was a very good product last time I used it.

nerd_flanders 08-04-2009 10:05 PM

[QUOTE=chrisn;309257]
Quote:

Originally Posted by poppameth (Post 309171)
I second CoverStain. I've also done this on occasion and it does seem to work. BIN also seems to work okay. Those are the only two I've ever tried it with. Neither is a real solution.:no: Both "may or may not" work for you.


I would not bet on either one. Neither one is labled for coverage over silicon and I would bet if slickracer took a fingernail over what he did it would not hold up.

Talk about being a nay-sayer. unless you can come up with a real solution you shouldn't criticisethese people trying to help and accept that the answer is not guaranteed to work. it's trial and error and those two are your best options.
In this case I would say Bin sealer would be the best option.to TRY .

nerd_flanders 08-04-2009 10:09 PM

Quote:

Originally Posted by ccarlisle (Post 309448)
In actual fact, that silicone adhesive your friend inadvertently used is a fine example of just how silicones work - well, that is those that are chemically of a certain structure (because not all silicones show adhesive proeprties - but close enough for the sake of this thread).

Silicones like this one attach themselves chemically to the substrate whereas other caulking compounds attach themselves mechanically to the substate. In doing so, silicones can attach themselves to pretty well any substrate much better than other products because they orient themselves in such a way that on one side of the bead (towards the substrate) they stick and on the other side facing you they do the opposite: they repel anything that tries to stick to them...:yes:

Chemical bonding and all that...but on the side facing you, you are looking at a very slick surface that as I said repels everything - much like the wax on the hood of your car...products just bead up once they land on a silicone and fall off. They do that by orienting the silicone molecules in such a way that the surface has very low "surface tension". That means everything rolls off it.

To put it into numbers, the silicone surface has a surafce tension somewhere around 30 dynes/cm...water has a higher surface tension around 72 dynes/cm. Now by physiochemical principles, the higher surface tension product (water) cannot remain comfortably on the lower surface tension product (silicone) - and the water rolls off.

Thus the only way to make something stick to a silicone is to give it the same surface tension as the silicone...don't ask how I know that, I just do. :laughing:

Ta-da... "fluorochemicals" to the rescue!!:thumbsup:

If you put "fluorochemicals" into a caulk or a paint, it would stick to silicones. Some products have "fluorochemicals" in them, but they ain't cheap.

Sooooo...95% of the products you try to put over that type of silicone wan't stick for very long. But one or two just might. Either spend your time trying to find that one or two products, or take it out and do it properly.

Here endeth the lesson...:whistling2: Not bad for a Saturday night :laughing: I gotta get a life...

What are flourochemicals and where can I obtain them or what products are they in???

fstwrtr 08-04-2009 10:11 PM

I suppose for the over achiever, who is intent on loosing sleep and wringing hands over such an issue, one could simple cut out the silicone caulk and start over. thus he can then move on to worrying about other major worldly issues.


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