window glue/sealant help.

[kashurst]

I was looking at the bonded in windows on my sealine at the weekend and noticed that in a few places the black gunge has gone a bit crusty. Any recommendations as what would be the best black gunge to re-do the borders with.
cheers

 

[moonraker 36]

any good polyurethane sealant will do the job.
http://compare.ebay.co.uk/like/2810...ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=63&ff19=0
the area will need to be cleaned(liquid glass cleaner)and dry, any old sealant removed.
use tape to get a nice edge if required.
if boat is in a hot climate you will need to do when temps are below 20's.
as the bond will skin too fast and you wont get a good finish.

 

[moonraker 36]

in the automotive trade we use sealants form these...
http://www.dow.com/polyurethane/

 

[SC500]

Sikaflex 291 is best suited for this purpose and is used by the pro's. Sikaflex do produce a range of products for auto and marine. If you have a specific requirement their website is very good. About 8-£10 per tube of sealant.

 

[jfm]

Sikaflex 291 is best suited for this purpose and is used by the pro's. Sikaflex do produce a range of products for auto and marine. If you have a specific requirement their website is very good. About 8-£10 per tube of sealant.

I agree. Do not imho use "any" polyurethane becuase the quality really does vary. I'd strongly recommend using sikaflex's extra UV-resistant product, which is called sikaflex 291i. It's made specifically for this job. Easy to buy - googlable

 

[moonraker 36]

yep sorry....
only been fitting bonded glass for 20yrs.

 

[moonraker 36]

not going to argue over different brands as their are loads..sikaflex is a brand name we all no.
but if you don't get the basic' right in the prep work...it wont matter which brand you use...

 

[jfm]

yep sorry....
only been fitting bonded glass for 20yrs.

I don't care if you've been fitting it for 2000 years. The facts are the facts. The different brands are made to different price points and spec, and have different levels of UV resistance. OP was advised by you to use "any", and I just wanted him to know there are different quality levels out there.

 

[moonraker 36]

thats why it says any GOOD pu sealant...and if you want one of the best you better use DOW...
thats why most of the trade use it and not sikaflex.
again not trying to argue over brands he will only get a good finish (even if he uses sika)if the prep work is good.

 

[kashurst]

what prep work is required - apart from digging out the old stuff. does the glass edge and the gelcoat need special cleaning ?

 

[moonraker 36]

because you wont get good adhesion to the contact surface's.
if they are not clean and grease free.
in the automotive industry we would also use a primer on the aperture and glass surfaces(black in colour).
as you are only back filling and not removing the glass and refitting I would use a sealant with slow setting time.
as before I wouldn't do the job in high temps as the bond will skin over fast if your trying to smooth the surface of the bond.
you can also get gas bubbles forming in the sealant giving it a swiss cheese affect when set.

 

[jfm]

Your first post moonraker said it makes sense for OP to use £4.99 sealant from the well known chemicals company "Tiger" for a labour intensive job on a very expensive boat. I disagree. I'm happy to leave it at that though, and agree to disagree

Yup, no question that prep/cleaning is needed, and primers should be used if Kashurst is scraping the old stuff out right back to the GRP and glass surfaces

 

[moonraker 36]

fair enough jfm..

 

[wakeup]

No one has mentioned fritting !

 

[moonraker 36]

lol...

 

[moonraker 36]

if I was kashurst..I would leave it alone unless really bad as its one of those jobs that can go tits up very easily...