I asked mixed in on a previous thread and didn't get a response so will try it on its own. If I use urethane, will that fill in all the unevenness? Or will Butyl tape be fine? I need to clean up the edges but the surface the adhesive sticks to has me a concerned a bit and don't when know how to address it. Thanks
Not sure it matters too much. It was suggested to me to use 3M panelbond. Sticks great to metal & easy to sand.
IF you have paint on there, remove it. Urethane (2 part) primer is ok, but no paint or clear. Some glass companies won’t install front or rear glass over a painted/ cleared window channel, guess the urethane doesn’t stick well to base/clear or single stage.
For urethane adhesive, 3M doesn't specifically say whether you can/can't apply over paint. They do say large areas of bare metal should be primed with 2 part epoxy primer and then primed with their 'Single Step Primer' before applying the adhesive. I'd guess you could clean up your surface (smooth it) and use their single step primer if you want best results. Here's the link to their product application guide: https://multimedia.3m.com/mws/media/467720O/2007-adhesives-coatings-sealers-application-guide.pdf
Sika also offers a primer, Sika® Primer-20, which can be used before applying their adhesive. They DO recommend removing topcoats/clearcoats from the pinchweld. They also specify body fillers (Bondo) should not be used on the pinchweld.... probably more important in newer cars where the bonded windshield is structural. Sika has extensive instructions in their Technician Training Manual: https://usa.sika.com/content/dam/dms/us01/2/AGR TTM Volume 3.3.pdf I was once involved with a project where we installed windshields into Navy Seal boats using Sika products. We had to research every single detail for that contract. For your Buick, I'd say just get a smooth surface, don't be too concerned about leaving color/clear coats there, and epoxy panel bond would be preferred over bondo for filling defects. Paint repairs with auto grade epoxy primer and for best results use the 3M/Sikaflex primers before applying the urethane adhesive. Butyl tape install is less critical since you don't need the bond strength of newer cars. Just get a clean smooth surface to ensure a good seal. I thought I used a special primer ounce upon a time but I'm not finding that now.
I ended up filling in the low spots a bit with JB weld. I used Dow Betaseal urethane since the surface had its ups and downs and felt this woukd fill in better thab butyl tape. The Beaseal kit came with a primer that went directly on the painted surface. I scuffed up the surface anyway. It is very strong as I was a bit sloppy with the urethane edges and it was super tough to remove around the trim clip studs. I think I'm good. Thanks all.
