by Bob Beranek
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Lamination separation (LS) is real and should be taken seriously. Most LS shows itself on a windshield’s edges, where the bonding occurs. Windshields are made from two layers of regular annealed glass and an inner layer of polyvinyl butyral or butyrate (PVB). Annealed glass used in windshields is the same type of glass used in picture frames and is usually about 9 mm thick per piece and offers little strength on its own. The strength and “safety” come when matching pieces of glass and the PVB fuse together. If the three parts separate when it’s being assembled the windshield is greatly weakened and the bond is compromised.

There are two ways LS shows itself, a cloudy, milky appearance and small bubbles usually appear near the glass’ edge. It’s usually caused by excessive heat which shrinks the vinyl lamination or by the intrusion of moisture between the two layers of glass that causes it to separate.

When bubbles are found, they occur primarily on the edges, due to the black frit paint that absorbs more heat generated from the sun. Depending on the amount and extent of the bubbling, the safety of the glass will be impacted. If you have LS, the adhesive only fuses the inner layer (9 mm of glass) to the frame, and not the whole glass assembly.

The cloudy, milky separation is caused when moisture in between the layers of glass. You’re seeing the laminate (PBV) reverting to its pre-autoclave condition, which has an opaque appearance. This also is a dangerous condition, because of the separation’s extent, for safe glass bonding. This type of separation’s cause can sometimes be the unsealed edge of the glass.

Those of you that have glass fabrication as an add-on to your services, probably have noticed if the edges of a freshly cut laminated glass part is not sealed after fabrication, a cloudy appearance may appear with time and exposure to the elements. This is because when cutting the lamination while processing the part, the lamination is stretched. Then the PVB is allowed to relax which causes it to recess between the two layers of glass that cause an access point for moisture, which allows it to separate the two layers of glass.

LS is mostly in the southern or hotter climates, though it does happen due to poor manufacturing as well. The cloudy conditions can be caused by glass fabrication but also by improper preparation of the windshield prior to installation. If the edges of the glass must have the excess lamination trimmed off for moulding fit or any other reason, make sure you seal the edges with your black primer. That way the edges are sealed and the cloudy separation will not occur.

I get weekly emails from the National Highway Traffic Safety Administration (NHTSA) that list the most recalls issued. There was one that caught my eye; it was on two General Motors vehicles, the 2016-2019 GMC Savana and Chevrolet Express vans.

Its recall identification number is 19V387. The title is what initially drew me in Incorrect Rear-Quarter Window Glass/FMVSS 226.  Tempered glass increases the risk of injury in the event of a side impact or rollover.

What was wrong with the quarter glass installed in the original assembly? Tempered glass has been used for quarter glasses for decades. According to the summary of the recall notice:

“One or both of the rear-quarter windows may be tempered glass instead of laminated glass. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 226, ‘ejection mitigation.”

What is FMVSS 226, “ejection mitigation?”

FMVSS 226, officially “49 CFR § 571.226 – Standard No. 226; Ejection Mitigation.”, can be obtained here.

If you have an engineering degree or speak “legalese” fluently you’ll probably get through it and completely understand it. I don’t have either ability, so I contacted some experts for an explanation. Here’s what I’ve learned.

FMVSS 226 is a relatively new standard, as it was introduced in 2011. There’s been a phase-in period for vehicle manufacturers until September 1, 2018, which is why we haven’t heard much about this until now. It says:

“This standard establishes requirements for ejection mitigation systems to reduce the likelihood of complete and partial ejections of vehicle occupants through side windows during rollovers or side impact events.” 

The 19-page standard goes on to explain the phase-in requirements, performance and testing parameters. My experts explained it is a new stand-alone standard that’s a directive from the government to vehicle manufacturers, mandating that laminated glass take a greater role in vehicle manufacturing for safety reasons.

The standard makes an exception for cargo vans and other specialty vehicles under 10,000 lbs. However, if you have a cargo van with a factory installed laminated quarter glass, I don’t recommend replacing that part with a tempered piece. We cannot interpret the language of the standard for our or our customers’ benefit.

The immediate concern, is that some of your dealer customers may want you to replace the tempered quarter glasses with laminated on the left rear-quarter position for long wheelbase vehicles and both left and right rear-quarter positions for short wheelbase configurations. Also, you should be proactive and inform your customers of this recall.

The long-term impact is not known at this time. There may come a time when all glass will be laminated in a motor vehicle. If that happens, new tools and procedures will have to be invented to deal with the change. I will keep you informed of new developments with this standard as new requirements are announced, and I will add the facts to my training courses to assure up-to-date knowledge.