Damp in a repair

[Brent Deines]

Let's not forget that alcohol effectively melts the laminate.

[Brent Deines]

The difference between using a cigarette lighter and a tool that utilizes the same coil used in a cigarette lighter is that the cigarette lighter begins to cool the moment you remove it from the socket so once applied to the glass it has already cooled to the point that it will not bring the moisture to boiling temperature. It just is not effective unless you have a way to control how long the coil will stay at maximum heat.

[GlassStarz]

Let's not forget that alcohol effectively melts the laminate.

I guess thats the age old question isnt it. Does subjecting every repair and the plastic layer inside the glass to extreme heat cause less damage to the layer than when you use alcohol knowing that many breaks dont get to the inner layer thus having no adverse affect to a large percentage of repairs ?
is it better to heat to a melting point every one to avoid chemicaly hitting some? Im sure everyone has thier belief and it probably wont change

[Brent Deines]

You are mistaken about "many" breaks don't get to the inner layer; most breaks do. Bullseyes, combination breaks, and most star breaks all reach the laminate, so unless you only do surface chips the alcohol will come in contact with it.

When a windshield is laminated it is heated with a sheet of PVB between the two layers of glass. The entire windshield is heated to the point where the laminate begins to melt, thereby bonding the two glass sheets together, so to say that 20 seconds of heat on the outside of the glass, not directly on the laminate, damages the laminate is a bit silly in my opinion. In the testing we have done even repeated heating with a moisture evaporator on the outside of the glass caused no damage to the PVB, but alcohol eats right through it.

We've had this discussion many times in the past, and I don't expect to change your mind Gary, but there is no question about the negative effect of alcohol on PVB, and there is no evidence that that when used in accordance with manufacturer instructions that a moisture evaporator damages the laminate. Now if left on longer than recommended, it is possible to damage the laminate a moisture evaporator just as it is with a heat gun or a torch.

Let's not forget that alcohol effectively melts the laminate.

I guess thats the age old question isnt it. Does subjecting every repair and the plastic layer inside the glass to extreme heat cause less damage to the layer than when you use alcohol knowing that many breaks dont get to the inner layer thus having no adverse affect to a large percentage of repairs ?
is it better to heat to a melting point every one to avoid chemicaly hitting some? Im sure everyone has thier belief and it probably wont change

[simplyweb]

I have noticed on a couple of repairs when I have heated from the outside to quite an high temperature ,the finnished job looks badly formed , it looks like a big flower shape .Is this with over heating or is it the interlayer de-lamming . It was on older repairs .looks worse looking inside out.

[Ridge Runner]

simplyweb,
If you do a search on "flowering" you'll find a wealth of information on that subject. Same goes for just about
any WSR question you might have. The archival portion of this forum is very helpful. I use it frequently.

[Brent Deines]

I have noticed on a couple of repairs when I have heated from the outside to quite an high temperature ,the finnished job looks badly formed , it looks like a big flower shape .Is this with over heating or is it the interlayer de-lamming . It was on older repairs .looks worse looking inside out.

That's why you have to let it cool. The hotter the glass the less pressure it takes to push the resin out between the glass and the laminate. That is what the flowering is; resin that seeps out between the glass and the PVB.

With older glass it could be de-laminating before heat is even applied. Usually you will see signs of this around the edges before it is a problem out in the center of the glass, but sometimes it is difficult to see with the trim in place. The frit band can also hide some de-lam problems.

On either older windshields or very hot windshields use the least amount of pressure possible to help keep flowering to a minimum.

[GlassStarz]

Well I wasnt aware of the heat being used to laminate which certainly makes me think twice when hearing the other companies maintain that the heat damages the laminate geez Brent ya changed the old dogs mind quit it my head hurts it was already full of stuff LOL

[Brent Deines]

If you ever get a chance to watch how they make a windshield, do so. It's really a pretty interesting process. I don't want to get too off topic right after lecturing everyone else about doing that, but another interesting fact about how certain types of glass are made is that to get the best quality of glass used glass needs to be re-melted. So if they run out of used glass they break new glass and add it back into the mix.

They also still position the PVB on one piece of glass and hand place the other before it goes into the oven, which is why from time to time you will find a fingerprint or a hair on one of the inner surfaces of the glass. They are supposed to wear gloves and caps so it is quite rare, but it does happen from time to time.

I know this kind of stuff is nerdy, but I really find it fascinating.

[SGT]

I have a sneaky suspcion Brent has quite a bit factual information and common sense logic to share with us all. It may even fly in the face of what past, current or future marketing hype may be promoting. Keep it up!