When we worked with the guys at CR Lawrence when we were developing the procedure for doing the flush mount windshields in the fiberglass replica bodies we built, I was told that the frit is ceramic and baked on at the factory. It's purpose is to prevent Ultra Violet rays from breaking down the urethane. I tried some of the primer that supposedly had the UV protection and was designed for use with the urethane adhesive. I think it was the Essex brand. I tried it on 2 windshields and the edges pulled. I followed the instructions on the can. I have often thought that if you beadblasted a border around the edge of your glass and then painted a polyester or polyurethane or epoxy,(something unaffected by the uv rays and the solvents in the adhesive),coating on the glass, that would keep the uv from breaking down the urethane and be less prone to peel off of the glass. I know that the chemists at CR Lawrence would not stand behind any glass we installed using the urethane primer and urethane adhesive..
I sure like using the urethane better than silicone. It tools better, stays workable longer, and doesn't peel at the edge like silicone does. I did some of those flush WS installs with straight urethane back in 90 or 91 before we knew better and the windshields are still in place. That is what I know, Later mikey

 

My understanding of the "pinch weld primer" is that it is to be used where there is bare metal on the pinch weld. It "can" be applied to the glass (why you would want to, I don't know). But it is VERY thin and how you would apply it evenly and thick enough as to not see thru it, I have no idea.

I don't understand how there is such a big deal made about urethane setting and epoxy over bare metal prior to the urethane, but then they say it is ok to brush some super thin primer out of a little can on the glass and pinch weld to apply the urethane to. I don't get that. I have not seen any tests on the pinch weld primer, but I can't see how it could have the same tensil strength and adhesion as the urethane or epoxy. I just don't get that.

As I see it (and plainly I know next to nothing about the technology of this product) I can not see applying it, and NEVER have applied it, to the new glass I am installing. I have went to ICAR classes on glass, I have installed them many times. I can not understand why applying this weld thru primer (that I did on pinch welds years ago when using butyltape) on a new glass prior to setting it on urethane. I just don't see that as a good way to do it.

Brian

 

Maybe I could have been a little clearer.
When I tried it (the primer) it didn't work.

 

Just to make things clear Mike, my post wasn't in response to yours, I was typing it when you posted.

Brian

 

I have a good friend that does all my glue in windsheilds for me. Even on the old muscle cars he uses some sort of paint pen? looking thing that has a square sponge brush type head on the end about 1"x1". He lays the glass with the inner portion facing up on a stand and using his finger as a guide on the edge of the windsheild he paints a 1" wide gloss black coating on the inner surface of the windsheild waits for it to dry a few minutes and then sets the glass in the urethane. Basically end up with a black frame around the glass to hide the urethane.

I have no idea what that paint pen thing is or who makes it but I would assume it is pretty standard in the auto glass industry.

 

Just to make things clear Mike, my post wasn't in response to yours, I was typing it when you posted.

Brian

Thanks

 

That is the "pinch weld primer". I have not seen it used on glass installation as you described. I am of course working with late model cars that have frit. We do probably two or three windows a day between in house and having a glass shop come buy to do it. I have never seen that primer used unless there is a scratch in the frit or on bare metal.

Brian

 

Here is your answer to your primer questions.

http://automotive.dow.com/automotive/after/products/UrethanePrimers.htm

This is easier than trying to explain it.

 

The guy I talked to is our "glass guy" at crash and safety. They sent him to "windshield school" last year since our procedures for glass installs on crash test vehicles need to be strictly adhered to. This is where the black primer thing came from. He has had 1 comeback on a rather war-torn Jeep Cherokee that sprung a leak. Apparently there was some severe rust behind the prep area that "mutated" further about 2 months later. The Jeep owner is a buddy of mine there and needed some assist to get it fixed. I do understand the need to prime for certain adhesives and some don't hold jackschitt unless primed. But none the less I thought it was a pretty simple solution.

I would also think if you bead-blasted the glass that unless the matl used was water thin and had a wet time of litterally hours, you would simply have a bead-blasted area for a frit. Maybe grey looking at best? I doubt it would soak in to cover. Ceramic? Makes sense. He did say it was a glazing/etching type application and by his description I'll buy that. How long does this have to last on my hot rod? 20 years? 10? How much direct sun? Probably lots. Nice day driver. Will it be used like my daily commuters? Nope. Used a lot? Yup. Will it last? I'm thinkin yes. If I lived in AZ or southern CA I might have issues. There must be some testing done to necessitate the use of a primer to the glass. My next issue will be the metal work to get the opening just right all the way around since it's originally in a rubber gasket. The 54s are a 1 pc with a slight curve and that gasket just bugs me. Might be several months before I even get there but I promise to document my solutions and share em with you guys. Maybe I shoulda got a 53? Nah!! Too simple...again.

 

Highlander- you said you used the primer on the glass. You masked your glass and glued it in with urethane. That was your simple solution. All of the primers that I have seen were pinchweld primers or designed to be used on a frit covered glass. The purpose of that frit on the glass is to create a UV barrier. I asked the rep at CR Lawrence as late as the beginning of last year if there was anything that would be able to be used as a UV barrier on a windshield glass without the baked on ceramic frit, so we could use the "better " urethane adhesive. They said NO. They are manufacturers of glazing supplies for industry and automotive. They also sell many of the more popular brands. Ask your glass tech about them. Maybe they were ill informed or just didn't like me. Either scenario is understandable. I have tried the urethane pinchweld primer on 2 separate occasions on new,unfrittered(?) glass with urethane adhesive and had to redo both windshields because they pulled away at the edges. My idea about beadblasting the glass and COATING it with a non-permeable material that would block the UV rays that break down urethane adhesives has not been tried, but I don't think it would result in a grey band if you used a black paint. also it would need to cure before you did the glue in. The beadblasting would do the same thing as an etch, I would think. Do you have the product name of this new etching ceramic uv blocking primer? Please post it or post a link to it's performance data. I am ready to buy some if it means that I can use the urethane adhesive on all of my flush windshield installations and it will be approved for use in that manner. It will make my job alot easier. Thanks for reading this, mikey

 

Mikey, Check my above post.

The frit primer can be used to create a frit as well.
I do alot of street rods, muscle cars and classics that way and have never had a problem.

 

Mikey, Check my above post.

The frit primer can be used to create a frit as well.
I do alot of street rods, muscle cars and classics that way and have never had a problem.

I looked at the link you provided an I couldn't find anywhere where it said it would create a frit. It did allude to it rather strongly though when it said that it would provide UV protection and long term durability. If you have had first hand experience with this material and use it in your business, then I will investigate it further for use in mine. I would like nothing more than to use the better urethane on these flushmounts and do it with some degree of confidence that I won't have to do it twice or worse have it cause an accident. Not to mention the added benefit of having a uniform band around the W/S for cosmetics. Thanks for the clarification, :thumbup:

highlander- If that (above referred dow primer),is the material that you were referring to then I thank you for starting this thread. mikey

 

50 chevy p/u. That picture of the primer with the square head applicator looks exactly like the stuff I was trying to describe in the post above. My glass guy has used it on numerous cars I have painted. He uses that stuff on clear non factory fritted muscle car glass in order to use the urethane window set. I HAVE NEVER HAD ONE ISSUE WITH ANY OF HIS INSTALLATIONS WHERE HE USED THAT METHOD. These installations have had chrome trim applied after the glass is set and you can only see about 1/8"-1/4" of the primer peeking out of the mouldings.

 

Your glass tech is doing it exactly right. As long as he is using the pinchweld primer as well.

Not using primer on the glass and pinch weld is like building a brick wall with no concrete. It won't last!
also thanks for confirming the fact that you don't need the ceramic frit to use the glass primer.
The link above refers to the primer as "glass/frit primer" thus creating your frit.

I think mikey was a little skeptical about it.
Don't be, trust me it works.

 

Pretty damn interesting to say the least guys. I think a little test is in order. :mwink: I have plenty of glass, urethane and pinch weld primer. Of course I think I will get the exact one you show. I will develop some sort of torture test and keep you posted.

Brian

 

Yes mike, black glass primer to create the frit effect and cover the seting area. The link 50chev gave us says what he says...prime the glass. I hope this helps you in future installs. We have plenty of glass around the plant to play with and I just may do my own "test" as well, but in all reality don't think it'll be needed. Last week he just set the glass in a racer that we did. Black primer. Looks just right.

 

Yes mike, black glass primer to create the frit effect and cover the seting area. The link 50chev gave us says what he says...prime the glass. I hope this helps you in future installs. We have plenty of glass around the plant to play with and I just may do my own "test" as well, but in all reality don't think it'll be needed. Last week he just set the glass in a racer that we did. Black primer. Looks just right.

I have no prob using something that works, but just saying "primer" could imply alot of materials that do not work. Some I have already tried to use in the manner you suggested. I didn't know what product you were using when you said "primer". you did not specify that it was the Dow betaprime 5500. The first I have heard of that material was when 50chevy posted that link, so I was skeptical when you said "primer". I learn something new every day. :thumbup: later,mikey