flowering?
Posted: July 18th, 2008, 12:36 pm
Can someone help me understand this effect? And how does resin viscosity and windshield tempature come into play.
Flowering is when the resin flows out between the glass and the PVB. There are several possible causes for this including the extent of the damage, the age of the glass, resin viscosity, heat, and pressure.
If you are working on an older windshield the PVB to glass bond is already beginning to weaken. In fact, you will often see air bubbles around the edge of the windshield where it is beginning to delaminate on its own. In extreme cases you will see flowering in the middle of an unbroken windshield. Therefore when you go to fix a rock chip you are much more likely to see flowering.
Adding too much pressure will force the resin between the glass and laminate.
Adding too much heat will thin the resin down so it flows into small areas faster, and also temporarily softens the PVB allowing the the thin resin to pass by a bit easier.
Low viscosity resin flows very well, but may tend to flower quicker than a medium viscosity windshield repair resin.
Another part of the equation is the equipment used to inject the resin. Delta Kits uses a very low pressure hydraulic system whereas most other systems use air to force the resin into the break, which requires considerably more pressure. Therefore, you can use a very low viscosity resin with a Delta Kits injector without too much concern for flowering, but may need to use a higher viscosity resin to minimize flowering with some other systems.
For the most part flowering is a cosmetic issue, not a structural issue, but obviously it is important to provide the most cosmetically appealing repair possible, so it is wise to consider all of the factors above and use common sense when choosing resin or applying heat and pressure.