Windshield Repair Forum

My old classic had the window channel sandblasted to bare metal and I painted it with a quality enamel paint. There is no ribbin seals present. My question is do I need to reinstall a ribbon seal or can I just use Betaseal U-428 directly on the painted surface without primer on the sill or back of windshield. Chrome pieces are screwed on over not like coupes. I expect the bead under the windshield has to be a proper thickness after setting so the chrome will fit properly. I know 3/16 is good..will a bead without a ribbon seal make this thickness or will the U-428 flatten too much. Thanks, Bob

According to the current AGRSS Standard when replacing automotive glass current standards must be met.Which means in a nutshell you are supposed to upgrade to Urethane, and the manufacturer instructions must be followed. If it calls for metal and glass primer you must use them. In your case I am concerned about your paint job. Did you do the metal restoration at your house? If so do you you understand that the paint adhesion to the metal is just as critical as the urethane adhering to the paint and glass. did you use metal paint primer and the correct paint for urethane bonding? The paint job may look good, but how well is it chemically linking up to the metal? The windshield retention is only as good as the paint retention.

Having said that; in your car, I would use a 3/8" butyl ribbon and back it up with a gunable butyl like R900. Use butyl primers.

Urethane it in. Use primer on pinchweld activator on glass Sika it. Just don't over do it on the top and sides you may want to change it someday.

Check out the link, for clear directions how to use U428 urethane. If you do not fit direct glazed windshields on a regular basis I would recommend you have it fitted by a trained fitter.

http://corporateportal.ppg.com/NR/rdonl ... al_Data.pd

Regarding keeping the glass at the right height from the pinchweld ( 3/16") , use rubber spacer blocks placed on the inside of the glass to block the glass to the correct height as soon as the glass has been fitted.

Make sure you have a tall bead and don't push to hard on glass. The moldings will set how high it should be. HTH

Assuming the repair is correct and the next step is the adhiesive, I'm looking at the actuall question about U-428 betaseal. It's primerless but low viscosity. We use U-428Plus which has a higher viscosity and still cost effective. If your experienced, that would be fine because you should know by feel or blocks (height blocks preferrably). If you've done a few but not everyday then check out the U418HV (high viscosity) also primerless. It's very stiff to the touch and is easy to work with when doing a conversion from the butyl to the urethanes. I think the regular U428 will allow the w/s to sink too far down too quickly in the case of an unforeseen problem like the height blocks are off or something along those lines. Keep in mind though 418HV needs a very very strong gun to run it. U428 plus needs a very strong gun. U428plus needs a good /better than running bathroom caulk gun. U428Plus is a very good middle choice that my company uses everyday all day. Good luck and try to have fun with it...