Cutting Lamination

In the past, I have discussed the art of laminated glass fabrication. We covered a number of subjects such as the equipment required and the mechanics of scoring, breaking the score, radius corners and finishing. Although there are various ways of separating the lamination, today I want to explain why care must be taken in using alcohol and heat.

The preferred method for separating the lamination between the two layers of glass during glass fabrication is by cutting the vinyl, not melting it. This is because heat causes the lamination to shrink. If too much heat is added to the vinyl (called Polyvinyl Butyrate or PVB), it will shrink too much and cause lamination separation right on the edges you need to bond or seal. Of course, there are additional safety concerns when using a lit flammable liquid as a separation method.

Lamination separation is seen in two ways: bubbles between the two layers of glass or a clouding effect originating from the edges. The bubbles are the vinyl shrinking from one or the other glass surface caused by concentrated heat application. The clouding effect is the glass allowing moisture between the two surfaces thus causing it to revert back to its pre-autoclave condition, which is the last step of making laminated glass transparent. If lamination separation occurs, the glass is drastically weakened and could not be considered “safety glass” anymore.

Some technicians think that eliminating the use of denatured alcohol and replacing it with the use of a heat gun fixes this problem. A heat gun is safer to use than lit alcohol, but it is still not recommended.  The heat is the culprit here—not the product or tool used. 

Cutting the lamination is still the best way to separate the cut piece from the stock piece. Some technicians use a straight-edged razor blade, which works fine. I find that the razor blade is a little too thick for use around radius corners.

I still think that an old tape measure blade is the best cutter of lamination for a cutter of glass. It is self-sharpening, flexible for both straight-a-ways and corners, and very cost effective. If you have one that broke recently and you haven’t already thrown it away, it is a fortunate find. But, even if you have to buy a six foot tape, ¾ “ or 1-inch wide, that tape should last you your whole career if used properly.

For the sake of safety and quality, cut instead of melting the lamination. It will pay off in the long run, and it is just as quick to do.