Sikaflex 291

[Quandary]

This is not exactly boaty but since the cartridge was purchased in a chandlery perhaps that is enough?
Our house was built in 1940 and the original ogee profile cast iron gutters and downpipes have lasted well. The spigot joints of the overlapping cast gutters are bedded in traditional linseed oil mastic but after 77 years some of the joints are starting to drip, not a terrible problem in itself but the original pitch pine fascias and soffits would be hard to replace if they were to start to rot. Where the joints leak, (about one joint in each of the four sides), I suspect thermal movement (gutters and fascia boards are currently painted dark green). I have raked out the hardened mastic and cleaned the metal to a coarse rusty finish with a wire brush and injected the 291 to seal the joints. I had waited from early May for three consecutive dry days to ensure the metal was really clean and dry but the sealant seems reluctant to adhere to the rough metal despite its texture. By contrast it adheres so well to my hands and tools that it takes days to remove. I understand that the sealant is cured by atmospheric moisture so I wondered if the surfaces are too dry and if a mist spray might help?
Anyone using this stuff regularly with any hints on making it stick.

 

[lpdsn]

Have you tried using the primer?

 

[alahol2]

I'd suggest using one of the sealants that says it can be applied to wet surfaces... CT1, PU40, Stixall etc.

 

[MikeCC]

If there's going to be continued movement, something that cures with more flexibility would be better perhaps. Roof and gutter sealant about 1/5 price of Sikaflex 291.

 

[Quandary]

If there's going to be continued movement, something that cures with more flexibility would be better perhaps. Roof and gutter sealant about 1/5 price of Sikaflex 291.

Tried that last year, very limited life. The original mastic worked for 3/4 of a century so ten years from a modern product might be achievable? Price is not the issue it is working at the top of a ladder with my knuckles raw from the roof tiles.

 

[Neeves]

If you cleaned up prior or subsequently with an oil based thinner - turps being the prime culprit you will not get good adhesion. It, turps, would need to be cleaned from the surface prior to application of the Sika and if used to clean up subsequently (it unfortunately is so effective) it wicks between Sika and surface and weakens the bond.

 

[zambant]

ct1 for sure

 

[alteredoutlook]

ct1 for sure

+1

 

[scottie]

Is this preparity to treating lock gates?

 

[RichardS]

I've just used Geocel 201 on the boat for the first time. It's a sealant and not an adhesive but it seems very easy to use and sticks to fairly dirty and unprepared surfaces. It dries in an hour or two (i think, although I didn't actually prod it until the next day) and retains flexibility so it's good where some there is going to be some movement.

You need a big gun to apply it though as it's too large for the B & Q standard cartridge gun. I bought a bigger one at Screwfix for a £5 which seems to work well.

Richard

 

[2Tizwoz]

Butyl mastic doesn't dry out and is clean to work with. It remains flexible, lasts indefinitely (no wasted cartridges) and will permit thermal movement in your iron gutters.

It's readily available on ebay and elsewhere.

 

[QBhoy]

CT1 is the business !
One of my friends has the Northern UK franchise. Can't speak highly enough of it.
Should be sold in more Chandlers. I even repaired a gash on the tubes of a Rib. Holds full pressure. Amazing stuff and can be applied wet or even under water !