Volume 5, Issue 6        November/December 2003

Inside Spalling
Pioneer Company Speaks Out on the PVB Issue
by Jon Thomas and Penny Chatterton

Almost 33 years ago, Frank Werner had the idea for windshield repair during a family vacation to Canada when his windshield was broken. Werner, who has doctoral degrees in aeronautical engineering and physics, decided during this trip that there must be a better and commercially viable alternative to auto glass replacement. He and a colleague, Gerry Keinath, then founded NOVUS in 1972 to focus on this new technology. 

Since its inception, we estimate that our franchisees and other international partners have successfully repaired more than 20 million windshields. And that’s just one company’s numbers—it is likely that at least 60 million windshields have been repaired since the concept was invented.

We estimate—conservatively, that is—that each repair conducted over the last 31 years has saved the vehicle owner and/or his automotive casualty insurance company an average of at least $150 per windshield by repairing instead of replacing it. This has resulted in an aggregate savings to vehicle owners and insurance companies of more than $3 billion. 

If our estimates are right on how many repairs have been completed, then the global savings from the entire windshield repair industry has been at least $9 billion. This does not take into account the avoidance of other costs of auto glass replacement such as windshield disposal with its impact on the environment.

The Windshield Repair Safety Record

During the many years that windshield repair has now been in existence, to our knowledge there has never been a single report, instance or claim of personal injury due to a windshield being repaired, or due to the phenomenon known as spalling (glass dislodgement from the interlayer of a windshield). To the contrary, our company guarantees that every repair will pass state motor vehicle safety inspections for as long as the customer owns the vehicle.

The question of a moisture-increased spalling risk was first raised in 1993 when the National Glass Association (NGA) reviewed studies on the subject prepared by PPG, Pilkington (LOF at that time), DuPont and Monsanto (now Solutia).

In a letter from NGA president Philip J. James written on July 11, 1994, to Brian O’Neill, president of the Insurance Institute for Highway Safety (IIHS), he stated, “After two and a half years of testing and rigorous review, focusing on the issue of humidity intrusion and the subsequent phenomenon of interlayer de-lamination or spalling, the [NGA] committee has been unable to reach any conclusion as to whether or not any increased risk to the driving public exists from flying glass shards.”

After reviewing the documentation provided by the NGA, O’Neill responded by saying, “We have not found a single, real-world example of an injury resulting from windshield spalling.”

O’Neill concluded that “the Institute does not believe a new standard that might have unforeseen effects … is necessary or justified without convincing evidence that it is addressing a real—as opposed to hypothetical—problem.”

Nothing has changed since 1993. In 1998, the IIHS published its own study of “Water Exposure of Damaged Automotive Windshield Glass and Spalling from Subsequent Impacts.” 

The conclusions from this study read as follows, “Results of this study show the risk of interior windshield glass spalling from non-collision impacts does not increase when damaged windshields receive even extreme exposure to moisture.”

The study concludes with the statement, “These results indicate that NGA’s concern that normal moisture exposure will reduce the effectiveness of typical windshield repairs is unfounded.”

There is still no evidence to indicate that the concern about spalling is anything but an unjustified, unwarranted attack on the windshield repair industry. We think such attacks clearly are motivated by those with a vested, economic interest in denying American consumers the cost-effective, safe option of windshield repair over windshield replacement. 

Our research and development department also continues to be active in the windshield repair testing arena. We have reviewed much of the testing that other organizations have conducted and have conducted and commissioned a number of scientifically valid research studies of our own. 

Specifically addressing the recently reopened issue of moisture migration into damaged and repaired windshields, in 1994 we commissioned Twin City Testing Corp. to conduct a study that concluded that such a phenomenon was not an issue.

The testing was conducted in accordance with the American National Standards Institute’s Test for Glass Penetration (ANSI Z26.1), which was and is incorporated by reference into the Federal Motor Vehicle Safety Standard (FMVSS) 205. Sets of 12-inch by 12-inch by 6-mm laminated glass were subjected to ANSI Z26.1 (1990) Section 5.12.3 impact testing, which requires no penetration of the impactor through the laminate and limits allowable glass/PVB delamination. 

The tests were conducted between September 1993 and January 1994. Repairs were performed at Twin City’s St. Paul facility by our chemist at the time, under the direction of Robin Smith, who was, at the time, chief operating officer of NOVUS. 

The first sets of tests were conducted with the following adjustment: the impact weight was doubled to one pound while the drop height was halved to 15 feet. This change was not expected to affect the testing results since the same force is applied as with the standard test specified in FMVSS 205/ANSI Z26.1. Other tests were performed per the standard at the prescribed drop weight and height. (See the table below for a breakdown of various tests conducted.) The time necessary to induce a moisture level in the PVB of greater than 2 percent was predetermined to be 44 hours in the study performed by Twin City Testing.

In every single case and every single sample of each case, the criteria of Section 5.12.3 were satisfied. The criteria were satisfied even with moisture-saturated, unrepaired laminates.

An additional determination was made with samples B, C, A2, B2, C2, E and F of the amount of spalled material. The averages were all less than 5.3 grams of material and all but one sample averaged less than 3 grams. 

Our test results and those of IIHS all support our assertion that an increased likelihood of spalling-based injury due to moisture intrusion does not appear to be a problem that can be substantiated in the laboratory. 

We also believe IIHS’s methodology is more successful as an attempt to mimic the situation in question than a pummel test in which the laminate is impacted repeatedly. Unless other testing procedures are developed in the future by the National Highway Traffic Safety Administration (NHTSA), FMVSS 205 and ANSI Z26.1 are the authoritative standards.

NOVUS's 1993-1994 Repair Test Results

Sample Group Number of Specimens Type of Damage Applied Edges Sealed with Silicone Condtioning Actions Drop Height (Ft)
A 12 Full crack Y 44-hour water immersion, repaired 15
B 12 Full crack Y 44-hour water immersion, repaired, exposed to 53°C / 99%Rh for three weeks 15
C 12 Bullseye Y 44-hour water immersion, repaired, exposed to 53°C / 99%Rh for three weeks 15
D 12 None N Ambient atmosphere only 15
A2 6 None Y 44-hour water immersion 30
B2 6 Full crack Y 44-hour water immersion, repaired 30
C2 6 None N 44-hour water immersion 30
E 14 Full crack Y 44-hour water immersion 15
F 6 Full crack Y 44-hour water immersion 30
Source: NOVUS Windshield Repair

Federal Motor Vehicle Safety Standards

We have also reviewed the FMVSS. There are several FMVSS standards that deal with automotive glass. Standards that deal with windshield retention are: FMVSS 208, FMVSS 212, FMVSS 216 and FMVSS 219. None of these standards deal with glass spalling. 

These safety standards deal with windshield retention under crash conditions or roof deflection in a vehicle roll-over. FMVSS 205 deals with specifying requirements for the penetration resistance of windshields. This standard was designed to minimize injuries caused by the occupant’s head tearing through the plastic PVB interlayer of safety glazing used in windshields in low-speed crashes. 

Windshield penetration was believed to be the cause of most of the disfiguring or disabling head injuries associated with windshield contact. Auto glass manufacturers developed a looser glass-plastic bond in laminated glass, allowing the glass to crumple away rather than tear the plastic PVB interlayer. NHTSA estimated in their evaluation in 1985 that FMVSS 205 resulted in the prevention of 39,000 serious lacerations and 8,000 facial fractures per year. (See NHTSA Report Number DOT HS 806 693 for additional details. Contact the NHTSA by phone at 202/366-0123 or visit www.nhtsa.dot.gov.) 

As you can see from the summary of the aforementioned NHTSA report, the purpose of FMVSS 205 was to minimize the significant number of injuries caused by windshield penetration. Indeed, the report concludes that this standard did, in fact, have a significant impact in reducing injury in motor vehicles. The FMVSS was developed originally in response to a significant number of injuries caused by windshield penetration.

Windshield Repair Standards

In the case of glass spalling caused by windshield repair, we still have not been notified or received any documentation of the first injury caused by spalling from a windshield repair. The call for a safety standard addressing a phenomenon where there is no evidence for its occurrence is unusual at best and self-serving at worst. This is not to say that we want to ignore any issues raised about windshield repair.

We would support additional testing for windshield repair if a universally accepted test could be developed that would accurately reflect the real-world environment. 

However, we are confident that the laboratory testing we have conducted to date and the test data we have reviewed support our position that windshield repair is inherently safe. 

We believe that there should be a windshield repair performance standard. The National Windshield Repair Association (NWRA) has published a windshield repair standard that addresses the minimum performance of windshield repair. 

Obviously, vehicle owners and insurance companies would bear the brunt of a large increase in costs if windshield repairs were limited. 

We are unaware of any injuries caused by spalling due to windshield repair. From our statistical base of more than 20 million windshield repairs that have been performed over the past 31 years, it can be concluded that spalling has not occurred under real-world conditions. 

There is absolutely no data that would warrant the need for a safety standard for windshield repair. We challenge other organizations in the auto glass repair and replacement industry to come up with a statistically significant number of spalling incidents that have caused injuries or damage. 

The auto glass repair and replacement industry does not need a retread of 1993 testing to tell us that we might have a theoretical problem that may exist in the laboratory. 

What the auto glass repair and replacement industry needs to supply are documented incidents from actual vehicle owners or insurance companies showing that we have a real-world problem. 

Unless it is proven otherwise, we believe that an increased propensity for spalling-related injuries caused by windshield repair is merely a hypothetical issue. We were very diligent to test this assertion. We are genuinely concerned about the safety of our customers, but also concerned about giving them the best value for their insurance dollar. 

We believe the auto glass repair and replacement industry would be better served by focusing on genuine safety issues that have more positive significance to the overall future and viability of our entire industry.

Jon Thomas is a senior mechanical engineer and Penny Chatterton is a chemist for NOVUS Inc., based in Minneapolis.

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