UV resistant caulking

[matt1]

At 6 years old, the largely decorative, rather than waterproofing, bead of caulking between the hull and deck flange is cracking and showing signs of black mould. I suspect it’s Sikaflex but I don’t know which variant. I’m keen to replace it as it’s unsightly. Any tips for doing so and what product would you recommend that has good UV resistance.

 

[rogerthebodger]

The correct Sikaflex for deck corking is 290 DC is specified as UV resistant

Sikaflex®-290 DC PRO

 

[thinwater]

The correct Sikaflex for deck corking is 290 DC is specified as UV resistant

Sikaflex®-290 DC PRO

Sika 290 DC is "specifically formulated for caulking joints in traditional timber marine decking" according to Sika. Both Sika 291 and Sika 290 DC are listed as professional and experienced products only. Product specs are quite similar.

How is Sika 290 DC better than Sika 291 for this purpose? Also Sika 295, which has excellent UV resistance and is rated for sealing GRP.

Sika suggests an adhesion promoter or primer for practically all of their sealant products, but for the most part I think this is only common practice for glazing (for through-glazing UV protection) and teak.

 

[rogerthebodger]

Interesting that I was told by a local Sikaflex technical rep that sika 291 is the same as sika 221 the only difference is that 291 is a marine designation whereas 221 is a general designation and cheaper.

 

[geem]

Geocel Works is the product we use. It's had pretty good UV resistance to Caribbean sunlight

 

[matt1]

Geocel Works is the product we use. It's had pretty good UV resistance to Caribbean sunlight

Thanks everyone

Is there a particular Geocel product you would recommend?

 

[geem]

Thanks everyone

Is there a particular Geocel product you would recommend?

WORKS. That's what it is called

 

[Rappey]

Is there a particular Geocel product you would recommend?

They do a specific silicon marine sealant.. which could be a good choice for looks over waterproofing as silicon seems to fare very well outside in the sun.

 

[thinwater]

The Works spec sheets are rather sparse, but the SDS reveals two things:

• It is a silane
• It is a Sherwin Williams brand.

 

[geem]

The Works spec sheets are rather sparse, but the SDS reveals two things:

• It is a silane
• It is a Sherwin Williams brand.

We have been using it to bed deck fittings and windows for 10 years. It has a longer shelf life than Sika. It cheaper than Sika. It's an MPS. Same stuff used in high rise buildings to install glazing.