I hope the 5200 holds up too. I tried Sikaflex 295 UV and that lasted about 1 year...problem with these Beckson windows is that the frame is a thermal plastic (it melts) and I believe it is polyethylene and such thermal plastics don't have any surface active molecular functional groups to promote chemical bonding as opposed to gelcoat which is a cross linked polyester that does contain some surface active molecular functional groups that do facilitate chemical bonding so with the Beckson portlights the Sikaflex failures seemed to involve loss of adhesion at the substrate surface, using primer or not as opposed to at the plexiglass surface. That's why I decided to try a known strong adhesive/sealant like 3M 5200. I cleaned the mating surfaces of both the frams and the plexiglass very well, first mechanically using a sharp scraper, followed by sanding with 60 grit (thermal plastics don't sand well) and then a solvent wash with xylene followed by a solvent wash acetone to remove any surface chemicals and moisture...I used only 60 grit to mechanically clean the plexi followed by solvent wash with xylene; acetone attacks plexi quite rapidly so I did not use it on the plexi...the apllied excess bead of 5200 bead all around the frame and pressed in the plexiglass...went back and pressed again after 24 hours and then again after 1 week...instructions on slow cure 5200 indicate that full cure can take upwards of 2 weeks so I felt that multiple pressings during cure might yield a better gasket type seal...I know it's a wait and see repair, maybe I'll be doing it all again but 1/4 inch plexi is not expensive so I'll use new plexi if crazing becomes unbearable and I believe that I will be able to clean the frames of residual 5200 with a sharp scraper as I did last two times.
Dwight Veinot C&C 35 MKII, *Alianna* Head of St. Margaret's Bay, NS d.ve...@bellaliant.net On Sun, Jun 21, 2015 at 11:35 PM, Brent Driedger via CnC-List < cnc-list@cnc-list.com> wrote: > I have heard that although 5200 is amazingly strong, the chemicals in it > attack the plexiglass and will eventually cause premature crazing. > I hope yours buck the trend. Keep us posted. > > Cheers > Brent > C&C 27-5 > Lake Winnipeg. > > Sent from my iPhone > > On Jun 21, 2015, at 9:25 PM, S Thomas via CnC-List <cnc-list@cnc-list.com> > wrote: > > I used 4000UV to caulk along the top of my > glued-and-screwed-on-to-the-outside-of-the-boat windows without frames, and > after a couple of years it pulled away from the Plexiglas. Not a lot, but > enough to form a small gap that water can flow through. Stayed stuck real > good to the gelcoat though, so I am trying to seal the small gap with > creeping crack cure. > > Steve Thomas > C&C27 MKIII > > ----- Original Message ----- > *From:* PME via CnC-List <cnc-list@cnc-list.com> > *To:* cnc-list@cnc-list.com > *Cc:* PME <dre...@gmail.com> > *Sent:* Sunday, June 21, 2015 21:11 > *Subject:* Re: Stus-List A good day > > > May your port never leak again, but if a different ports leaks consider > not using 5200. I like 4000UV. > > > - > Paul E. > 1981 C&C 38 Landfall > S/V Johanna Rose > Carrabelle, FL > > On Jun 21, 2015, at 7:48 PM, cnc-list-requ...@cnc-list.com wrote: > > the 5200 that I used to rebed the > fixed portlights in my Beckson windows is sound with no leaks after 2 > weeks, only time with more will tell how this repair holds up over the long > run but right now I am happy: > > > ------------------------------ > > _______________________________________________ > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go to the > bottom of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > _______________________________________________ > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go to the > bottom of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > > _______________________________________________ > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go to the > bottom of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > >
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