difference in these ahesives?

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Sailingsaves

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So the forum has advised in the past that the following are great substitutes for the very expensive Sikaflex:

That is:
Tek 7 is great http://www.novatech.be/Default.aspx?WPID=328&L=E&PID=107
CT 1 is great http://www.sealantsonline.co.uk/ProductGrp/CT1_Unique_All_in_One_Sealant_Adhesive

All of above cost approx £13

but a building mate has just recommended PU 18 http://supplies.trulypvc.com/products/366-pu18-polyurethane-sealant-and-adhesive.aspx for less than a £5. Being PU it comes in a metal tube and he says it is brilliant. He gave me the dregs of an old tube and the cured bit sticking out end had great tensile and shear resistance.

Anyone have practical experience and able to compare these?

I was planning on fixing my roof with tek 7 that I have already forked out for.
 
I used pu18 when repairing my leaking hatches. It didn't bond to the Acrylic glass. stuck like shlt to the ali frame though.
 
Can't compare them but suggest look at the manufacturers datasheets. I'm a CT1 fan, it's worked well for me including for rebedding an opening hatch window & fixing solar panel corner mounts to campervan roof so personally I'd probably stick to what I know works well & pay a bit more...
 
Sailingsaves said:
a building mate has just recommended PU 18 http://supplies.trulypvc.com/products/366-pu18-polyurethane-sealant-and-adhesive.aspx for less than a £5. Being PU it comes in a metal tube and he says it is brilliant. He gave me the dregs of an old tube and the cured bit sticking out end had great tensile and shear resistance.
Click to expand...

If you follow your link, you'll see that the manufacturer specifies it isn't suitable for salt water environment, some plastics or an underwater environment. Whilst this may not rule it out for some jobs, it explain why it's only five pounds a tube.

J.
 
vyv_cox said:
although Puraflex PU40 costs less than £5 and appears to be very similar indeed to Sikaflex 291.
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And since the company making it was taken over by Sika, it now comes in aluminium cartridges instead of plastic, like Sikaflex does, and is labelled made in EU not made in UK.
Makes you wonder.
 
Pu 40 seems to set harder than sikaflex 291, very similar though. Toolstation stock it. One thing I like about sika is the abiltiy to split the fitting. Not really tested that out with pu 40.
Anyway I'm not sure of the original posts point as Sikaflex 291 is only 9.99 at marinestore. Other specialised grades can be priced up - if you are getting technical.
 
I bought some StixAll Adhesive & Sealant 290ml from Toolstation for a job at home. I was using another product and noticed is could be used in seawater but it set to a very hard material and so not really a Sikaflex substitute

StixAll also states that it bonds under water so OK to use in the rain or when everything is wet. It comes in clear, black and white and so I bought some clear and some white. The clear worked as expected and set very hard. However, the white seems to have remained flexible and feels much like Sikaflex.

I might try it on some wood or fibreglass offcuts and leave it somewhere wet for a few months just to see how it stands up.
 
vyv_cox said:
If you mean Stixall Extreme Power it is a hybrid polymer, of the same type as CT1 and others that can be used on wet surfaces. PU40 and Sikaflex 291 are polyurethanes, not the same stuff, cannot be used in the wet.
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Yes, this is the stuff I bought, thanks for the information. I didn't mean to compare the properties with Sikaflex 291 other than the "texture". It felt similar to a medium - high modulus Sikaflex product. I thought it was very odd that the clear version felt more like araldite when cured but the white version was definitely "rubbery".

I can think of a few uses for a left over tube if it does bond a variety of materials even when wet. Pity that I binned the last empty translucent variety, I could check the active ingredient list. Surprising difference between translucent and white, perhaps I bought a wrongly packaged batch.
 
vyv_cox said:
If you mean Stixall Extreme Power it is a hybrid polymer, of the same type as CT1 and others that can be used on wet surfaces. PU40 and Sikaflex 291 are polyurethanes, not the same stuff, cannot be used in the wet.
Click to expand...

Why is that then, since all 1 component polyurethanes rely on moisture for curing ?
 
Personal favourites are stixsall and PU 18, used both extensively inside for placing bulkheads, applying skin ply to them and filleting bulkheads before tabbing, really great stuff, plus you can buy a box of 12 PU18 cartridges for £35 on ebay, definately worth a go.
 
I've just stumbled across OB1 whilst shopping for CT1, and subsequently ended up here! Does anyone have any further feedback on OB1? I note that blurb doesn't seem to mention saltwater use, whilst CT1 does. Is this a worry? TIA!
 
syvictoria said:
I've just stumbled across OB1 whilst shopping for CT1, and subsequently ended up here! Does anyone have any further feedback on OB1? I note that blurb doesn't seem to mention saltwater use, whilst CT1 does. Is this a worry? TIA!
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It came up in this thread a few months ago. Screwfix OB1 sealant / adhesive

There were posts about the "similarity" with CT1 and that it was actually an improved formulation. Also a threat of legal action plus mention in advertising that the OB1 formulation had been in use for over 15 years and made by a private company. I could not find details of the manufacturer and it almost seemed to be a big secret. It appeared reasonable to assume that some sort of legally binding agreement had been signed regarding direct competition or comparison with CT1 by name (could be wrong).

My memory of the MSDS data is that OB1 was essentially the same as CT1 apart from an additional component. I can't remember what it was but did write that I thought it likely to enhance cross-linking to either speed up setting time or strength of the material, probably both (by promoting formation of urethane links).

I pretty much assumed that if CT1 was suitable then OB1 would work as well, probably slightly better. I was going to buy some for my boat but Covid-19 knocked that idea on the head and I suspect others had the same problem.
 
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Thre are may hybrid/ coplymer adhesive sealants similar to CT1 and OB1 .... Everbuild's Stix All is another which Vyv has mentioned in the past

If you want a slightly less expensive polyurethane adhesive sealant than Sikaflex Puraflex 40 ( PU40) is probably a good choice

Both StixAll and PU40 are made by Everbuild which is a Sika group company
 
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