CT1 anyone?

[wombat88]

I hear a lot about CT1's magic qualities, applications under water etc etc. Is it wonderful stuff? Is it a cheaper alternative to Sikaflex? When it goes off is it hard or is it a bit like silicone? Can you sand or paint it?

I'd be interested to hear from anyone who has used it, particularly on an old wooden boat.

 

[Tranona]

Used it for all sorts of things on my refit project. Good adhesive sealant, for example bedded down the new engine beds (mahogany) onto the old (iroko) in addition to fastenings. You can see the new beds in the first photo being trial fitted. Would not use it for anything really structural without fastenings. Even used it to bed wood plugs as in the second photo.

 

[fredrussell]

In my experience CT1 has a longer shelf life than Sikaflex. I’ve forgotten the name but there’s a cheaper version of both of those that Toolstation sell that people often mention positively on here, someone will be along to tell you soon I reckon…

 

[vyv_cox]

In my experience CT1 has a longer shelf life than Sikaflex. I’ve forgotten the name but there’s a cheaper version of both of those that Toolstation sell that people often mention positively on here, someone will be along to tell you soon I reckon…

OB1 at Screwfix. Puraflex 40 at Toolstation instead of Sikaflex.

 

[wiggy]

I love CT1, all my skin fittings and seacocks are bonded In place with it.

 

[jamie N]

CT1 has never let me down, has a good long tube life and remains 'non-hard'.
It isn't like a weld, but will keep things stuck together very well, and does help keep my carvel boat afloat with it's 'wet sealant' properties.
I get mine from Toolstation.

 

[LadyInBed]

OB1 £15@ Screwfix, £7.50@ Wickes
Puraflex 40 £7@ Toolstation
Looks like Screwfix will come and do the job for you at that price!

 

[LiftyK]

Two things about CT1
1. It works
2. When you use it next time it still comes out. It is the only sealant/adhesive product I've used where I get to use the whole tube, over many months, without most of it going rock solid

 

[QBhoy]

It’s great stuff. Not so great if you need to remove the thing it’s on again though.
I actually successfully sealed a hole in a Sib dinghy with it.

 

[Ardenfour]

I used it to seal around a brass fuel tank filler where it came through the deck. After about a year it became sticky and eventually disintegrated. I've since used EB25 (not sure if it's similar), to seal along aluminium/glass windows. 1 year later it too has become sticky and lost its adhesion. Maybe these hybrid sealants don't like metal?

 

[Restoration man]

Not sure if your aware but ct1 has changed it’s now called ct1 tribrid ,they say it’s better ,but as far as I’m concerned the jury’s out , it’s cured texture has changed it now feels more like silicone when it’s cured and it doesn’t stick to anodised aluminium as good as the old ct1 , they say it’s loads better product but I think it’s been changed for an inferior product thats environmentally friendly ,in reality a poorer product , I’ve used the old product above and below the waterline and it’s aways been great not sure I would use it below the waterline with this new version

 

[LONG_KEELER]

I found the "Clear" less effective than other colours.

I've only really used it for skin fittings and joints in compression . I tried using it to stick down solar panels temporarily but it didn't last long.

 

[oldgit]

CT1.
Have used it with great success on many jobs, both above and below waterline.
However , when used to seal windows and frames !
Providing you make sure that the surfaces are ultra clean CT1 will adhere and seal leaky windows , even when the boat hull is flexing.
If the windows are carefully masked up it is possible, with thin bead of the clear stuff, to get a neat and virtually invisable seal.
It will over a couple of years begin to become sticky and opaque and start to detach from the alloy frame and glass.
No big deal, just remove with stanley blade and re-apply.
Suspect problem is direct sunlight.

 

[dankilb]

As I’ve posted on a few of these threads recently - beat in mind PU40 is a pure polyurethane whereas CT1/OB1 are ‘hybrids’ (as is Sika 291). This explains the difference in price for P40. All are good products!

 

[Hacker]

We use EBT+ above and below waterline if we want adhesive. Personally I would use butyl to bed windows and deck furniture.

 

[vyv_cox]

As I’ve posted on a few of these threads recently - beat in mind PU40 is a pure polyurethane whereas CT1/OB1 are ‘hybrids’ (as is Sika 291). This explains the difference in price for P40. All are good products!

I was under the impression that Sikaflex 291 was a polyurethane although it is some years since I bought any. Sikaflex 291i All Purpose Polyurethane Sealant €16.95 - bluemarinestore

 

[wombat88]

Ta all, I'll slap CT1 all over the place and see how we go!

 

[LONG_KEELER]

OB1 £15@ Screwfix, £7.50@ Wickes
Puraflex 40 £7@ Toolstation
Looks like Screwfix will come and do the job for you at that price!

Well done that man !
Half price OB1 at Wickes compared to Screwfix.

 

[Malabarista]

At the risk of repeating myself (albeit a long time ago) i often use CT1 as part of my job. When using it, in order to get a nice finish and not end up with it all over the show you need two things. An old container mug/cup/glass etc full of warm water with a LOT of washing up liquid in it and an old spray bottle containing the same. My application technique is as follows: first clean the area to be sealed with multisolve or acetone. Then apply CT1 in a nice even bead ( more is always better) Then spray the CT1 and adjacent areas with soapy water liberally then soak finger tips in the solution until they are very wet and using either your finger or an equally soaked spatula ( ice cream stick etc) slide the excess gloop forming a neat bevel edge. As the excess builds up on your finger/stick put it straight into the cup of water where it will float free and be contained. This stops it becoming a mess and anywhere. As long as your finger is nice and soapy the CT1 won’t stick to you or the surrounding area ( hence the spray. )Apologies if you all knew that anyway.

 

[dankilb]

I was under the impression that Sikaflex 291 was a polyurethane although it is some years since I bought any. Sikaflex 291i All Purpose Polyurethane Sealant €16.95 - bluemarinestore

The price alone made me assume it was a hybrid…!

Comparing the TDS PU40 and 291 are remarkably similar. Both also made by Sika group of course!

Both are also substantively different to OB1/CT1 (which have higher modulus and hardness, but lower elasticity, and - importantly for me - greater bond strength).