There are major defects happening with laminated glass, if the process is not executed properly. Most prominent of such problems is de-lamination. This happens mainly due to the poor bonding between the glass and PVB sheet. In my previous post on laminated glass basics, I had mentioned about the clean facility requirement for lamination process, if this is not followed in the facility, there are chances for dust to stick on to the PVB and at a later stage, resulting in de-lamination. Waviness in the glass is also another reason for de-lamination: waviness in the glass can happen mainly due to poor quality tempering and even in annealed glass which has high amount of inherent waviness. De-lamination mainly occur at the edges where chemical bonding is weaker. De-lamination may also happen when the unit is over exposed to water, mason errors (like improper cutting), applying poor quality sealants, etc.
The next major which could be found in laminated glass would be optical distortion. This is of major concern when the lamination process used is cast resin type, which results in thickness variation, causing optical distortion.
Don’ts with laminated Glass:
– Not recommended to be used for point fixed glazing, except if one glass is toughened
– When heat absorbing glasses with a high absorption rate is used in laminated unit in a south or west facing building, they are susceptible to thermal breakage.
– Edges of laminated glass should not be exposed, especially to water.
– Laminated glass must not be installed without at least support at two sides
– While using the sealant, it should be ensured that it is not an organic sealant (which results in de-lamination at the edges)
– Laminated units with out toughened glass can be cut at site, but has to be done carefully without damaging the edges.
Myths about laminated glass:
– De-lamination of laminated glass is a common problem! – As mentioned above in the beginning of the post, de-lamination occurs due to the way in which the manufacturing process is carried out and with the quality of glass and toughening done.
– Laminated glass is weak! – With a similar thickness annealed glass, on comparison, laminated glass is obviously not weaker. A simple real life example can resolve this doubt: just check if the windshield glass of your car is laminated, and if it is, just imagine what is the wind load that it takes! (that too in most cases, it is just a 2mm + .73mm PVB + 2mm laminated unit).