3M 4000 UV Turning to Tar!? WTF

[Islander Jack]

I'm seeing the same problem with the white version. I sealed my toe rail with the stuff last summer and it's gooey in many places now. I think maybe I got a little teak oil on it, or maybe the teak oil leached through the wood to the sealant. We just had a hard rain and the boat didn't leak so I'm just going to leave the gooey 4000 UV on.

Previously I used 4200 but it detaches after two years, so I tried 4000 UV.

 

[SloopJonB]

Since it's a port lens, I'd use Dow 795

 

[Crash]

S2 used Dow 700 Industrial Grade. Its available in Black. After 30 years, the ports on my S2 9.1 were still dry and not leaking...

 

[Pertinacious Tom]

I have found that, as others have stated, if the surface is not scrupulously cleaned you can have all sorts of problems with sealants. If silicone was the previous sealant you need to remove all of it. That means using a silicone remover, (3M makes one) scraping the residue off with a scraper and then a razor blade, wiping with mineral spirits then alcohol and making sure the surface is dry when you apply the new sealant. Other sealants need different solvents but the process is basically the same. Do not take shortcuts in the prep.

I always heard it was impossible to get silicone residue out of gelcoat and it sure seemed that way when I tried it but that was before the internet.

I have avoided silicone on boats for a long time.

 

[samwise]

I have used Sikaflex 295 with good success. Cleans up with rubbing alcohol when ( not if) you get all over the boat and yourself. The only down side is that you also need to buy the primer which costs way more than the tube of caulking. You only need a small amount of the primer and it expires really quick but it was highly recommended by my chandlery (go figure). End result, no leaks in my glued in curved windows.

 

[SloopJonB]

I have found that, as others have stated, if the surface is not scrupulously cleaned you can have all sorts of problems with sealants. If silicone was the previous sealant you need to remove all of it. That means using a silicone remover, (3M makes one) scraping the residue off with a scraper and then a razor blade, wiping with mineral spirits then alcohol and making sure the surface is dry when you apply the new sealant. Other sealants need different solvents but the process is basically the same. Do not take shortcuts in the prep.

I always heard it was impossible to get silicone residue out of gelcoat and it sure seemed that way when I tried it but that was before the internet.

I have avoided silicone on boats for a long time.

You can clean it off well enough that it won't affect other types of sealants but it is extremely difficult to clean it off well enough to avoid fisheyes in paint.

 

[Hobie Dog]

I have used Sikaflex 295 with good success. Cleans up with rubbing alcohol when ( not if) you get all over the boat and yourself. The only down side is that you also need to buy the primer which costs way more than the tube of caulking. You only need a small amount of the primer and it expires really quick but it was highly recommended by my chandlery (go figure). End result, no leaks in my glued in curved windows.

Just looked up the specs on West Marine and no mention of needing a primer, nor do I see one listed. Stuff is $32 a tube!

States:

"Material Incompatabilities: Not for bonding glass or use over silicones; Not for use as a deck seam sealant"

Whatever my windows are originally bonded with I am pretty confident it is not silicone so good there. My windows feel like they could be glass but there is no way they could be glass could they???

 

[Ishmael]

I have used Sikaflex 295 with good success. Cleans up with rubbing alcohol when ( not if) you get all over the boat and yourself. The only down side is that you also need to buy the primer which costs way more than the tube of caulking. You only need a small amount of the primer and it expires really quick but it was highly recommended by my chandlery (go figure). End result, no leaks in my glued in curved windows.

Just looked up the specs on West Marine and no mention of needing a primer, nor do I see one listed. Stuff is $32 a tube!

States:

"Material Incompatabilities: Not for bonding glass or use over silicones; Not for use as a deck seam sealant"

Whatever my windows are originally bonded with I am pretty confident it is not silicone so good there. My windows feel like they could be glass but there is no way they could be glass could they???

Sloppy work at West. Oh, what a surprise.

Here's the official word from the data sheet.

Sikaflex®-295 UV black is intended to be

used as an adhesive and/or sealant in

bonding applications for polycarbonate

windows and acrylic (PMMA) windows.

Black: Use in conjunction with Sika®-

Cleaner 226 and Sika® Primer 209N.

Prior to use, always refer to installation

guide available at www.sikaindustry.com/

ipd-marine-window-295.

 

[Hike Bitches!]

Whatever my windows are originally bonded with I am pretty confident it is not silicone so good there. My windows feel like they could be glass but there is no way they could be glass could they???

HD, the original windows in my boat were glass...anything is possible!

 

[Hobie Dog]

Negative on the glass windows. PO put one of those Coast Guard inspections stickers on one of the windows. It was expired so I scraped it off with a razor blade and in the process I put a few scratches in the window. As we know a piece of glass would not scratch like that.

So with the storm coming I had to get something on there as it was leaking really bad even with the dink on top of it. So last Wednesday I dug out as much of the old caulk as I could, cleaned with Acetone and put down fresh 3M 4000 UV because that is what I had and was running short on time. Setup just fine and not a single drop in the boat even with all that rain on Friday!

See how long it holds up this time!

 

[Pertinacious Tom]

Well, now you know what to do if it turns to tar.

 

[Hobie Dog]

True but I only got about 12 months out of the last application, it's not a job I want to do on an annual basis! If it turns to tar again I'll try a different product.

 

[Hobie Dog]

And thanks for all the help on this. Looks like I am at least good for a year and then see how it goes...