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Luther · 09-05-2018, 15:22

This is a shot of my toerail.
There is a routed channel 1/4" deep between the aluminum and the blue awlgrip.
It was originally filled by the Marina boatyard with Black 3M 5200 which disintegrated within 18 months.
I have now cleaned it with a Dremel tool and "painted" it with epoxy resin.
I will now mask and fill the channel with.....?
I'm thinking teak deck caulking would have the best UV resistance if it will stick to the epoxy?
I'd appreciate any suggestions for a permanent solution.

puffcard · 09-05-2018, 15:37

The best UV resistant sealant is Silicone. No one here will recommend it, but it has excellent flexibility, excellent UV, works well with plastics and adheres well. For that project, I would use 3M 4000UV. I've been impressed with it on deck fittings and chain plates.

TheOffice · 10-05-2018, 03:09

Sikaflex 295 is uv resistant as well

Seabeau · 10-05-2018, 03:41

Butyl Rubber tape.

Sailmonkey · 10-05-2018, 04:10

Quote:

Originally Posted by Seabeau

Butyl Rubber tape.

Is not UV resistant and will not fill the gap the OP is describing

Groathill · 10-05-2018, 08:59

Back in 1981 I joined the fiberglass hull and deck using an aluminum toe rail with 8mm SS bolts every 10cm and Sikaflex on my 33ft boat.

Some of the Sikaflex (white colour) has been exposed to the sun all these years and still has a solid slightly flexible surface if I poke it wit a sharp point - and there are no leaks. Do not remember the Sikaflex number.

Nightcrawler · 10-05-2018, 12:22

We have original Sikaflex on our 28 year old teak decks. Still flexible. Having done some touch up I found it also sticks to anything, plastic (sunglasses), blue jeans, leather (wallet), aluminum boat hooks, pretty white gel coat cabin roof and anything else within 20 feet of your work space.

stu291 · 16-09-2019, 14:51

I just checked the CLR website- butyl caulk they claim it's unaffected by temperature and UV

cooties · 08-10-2020, 12:43

Anyone know what's up with the latest on UV caulk? Have formulas changed or chemicals been banned? The Sika 295 used on my deck/hull seam is almost completely failed in less than 2 years, as installed by the boatyard.

Thumbs Up · 08-10-2020, 13:55

Sikaflex 295 UV is what I used for all of my windows. Within a year it smears black streaks wherever you touch it. Complete failure. I have had way better luck with black automotive grade permatex silicone rtv sealant. Sika (and sikaflex) is a brand. They make hundreds of products. It is like saying you used 3m sealant. You would have to be more specific. 3M 4000UV is a great product but you have to work fast, it skims over very fast.

**s/v Jedi** · 08-10-2020, 14:33

Best UV resistance probably Dow Corning 795 structural silicone. This is what is used for glazing in sky scrapers.

Also, cheap from the big box stores: DAP window & door sealant which is about the same product.

I had a very bad experience with 3M 4000UV which should be the correct product but it fails in months.

cooties · 08-10-2020, 15:27

Quote:

Originally Posted by Thumbs Up

Sikaflex 295 UV is what I used for all of my windows. Within a year it smears black streaks wherever you touch it. Complete failure. I have had way better luck with black automotive grade permatex silicone rtv sealant. Sika (and sikaflex) is a brand. They make hundreds of products. It is like saying you used 3m sealant. You would have to be more specific. 3M 4000UV is a great product but you have to work fast, it skims over very fast.

I specified 295 in my comment. Everyone tells me it should have lasted longer than 1.5 years, that re-caulking every 5 years is more the norm. The odd thing is there are several seams that are fine now at the 2 year mark, and they see the same amount of UV.

When you say work fast, what do people typically do when caulking? Seems like 15-20 minutes should be fine? I'd guess you'd want to move somewhat quickly... or do people like to first lay down the entire seam first, then go back over it with a wet glove to smooth it out in one go? In which case, yeah, 15-20 minutes might be too short of a window for 50 feet. Unless I have a helper.

Hrm.. Well, I can try the 295 again.. Maybe it was just a bad batch. It does get moldy as well. I've been told that there used to be anti-mold chemicals in these products, but no longer. The fine-threaded Shurehold deck brush (the blue one) actually seems to clean it up fairly well though.

Thumbs Up · 08-10-2020, 15:59

The 295 UV is overpriced garbage. You are supposed to use a special primer for it too. One with a very short shelf life. It gets brittle and chalks. 3M 4000UV skins over almost immediately. You have just enough time to tool it with a finger and pull the tape (5 minutes) so is best for smaller jobs.