The Stress Crack Myth

Bananas do not grow on trees.

Bats are not blind.

Duck quacks DO echo.

Bulls do not become angry at the color red.

Windscreens do not stress crack.

Bananas grow on something the size of trees, but the banana ‘tree’ is not actually a tree. The banana plant, which can grow up to 25 feet, is actually the world’s largest perennial herb. When you carefully inspect a banana plant, you’ll notice that it doesn’t have woody fibers. It has strong stalks and leaves, yet it lacks the trunk and branches that would qualify it as a tree.

Bats see in black and white. At night they see better than we do. They lack color receptors; but in low light, we can’t see colors either.

Duck quacks have no special sonic quality to prevent echoing.

Bulls and other cattle are partially color-blind; they cannot see the color red. They are, however, defensive creatures and will charge when threatened, frightened or annoyed.

Education is the debunking of mis-education. This includes spotting and correcting the many myths emanating from the internet, folk wisdom and word of mouth. We have all been taken in, at some point or another, by a modern myth. The countless ‘stress cracked’ windscreens returned to wholesalers as defects are, 99.9% of the time, rocking horse shit. There is usually an explanation.

Windscreens do not crack spontaneously. This cited phenomenon is usually attributed to bad or incorrect fitting. In some instances the crack will be emanating from an impact, and in some rare cases extreme thermal fluctuations can be a cause. The study of fracture mechanics does not accommodate for laminated windscreens which have, “cracked for no reason”.

Stress-cracked windscreens: a trade fallacy.

A Condemned Windscreen?

According to the repair criteria set out by a national and insurance ‘approved’ windscreen repair and replacement company, this windscreen is not eligible for repair:

Windscreen Front Elevation

Why?

There are too many chips.

Whilst the windscreen isn’t exactly peppered, there clearly are five areas of damage, but they’re spread out and well apart. Would the same company be happy to attend to the same car and windscreen on five separate occasions? We don’t know what their policy is and whether or not they have a way to monitor it, but anyone would think they would for sure. So what’s wrong with repairing all five in one sitting?

A closer look at each chip.

A:

It’s low down and by its position, size and type not intrusive. However, it is still visible. From the image it does look like it may even have had a repair attempted previously and the car owner confirms this is the case. In any case, if it has had a repair, it was a very poor attempt and looks like it can still be improved by re-repairing. The structural element of the damage looks untouched, and only the impact crater has been filled.

B:

This one is in the A Zone. It’s tiny. The diameter of a five-pence piece is 18mm. Some man maths-style deduction suggests the damage is between 3 and 5mm. The permitted repair criteria for an A Zone repair is 10mm making this a viable repair on all counts.

C:

Chip C, by coincidence is in the C Zone. The coin provides a useful scale and in any case, looking at the damage (before or after repair) is obscured by the rear view mirror so the emphasis here would be on how it looks cosmetically from the outside, provided it is repaired structurally. There is an obvious sign of moisture in the break, therefore no issue in why this cannot be repaired.

D:

Chip D. A classic ‘bees wing’ with some ‘daisying’ around the impact mark. It’s low down in the C Zone and repairable.

E:


Chip E is in the perimeter of the windscreen known technically as the D Zone. It’s a tiny ‘half-moon’ style break with more surface damage than structural. There are a couple of minute pit marks next to it which are easily addressed (sometimes referred to as vanity repairs).

Overall, four viable repairs and one re-repair. Chip A was not cited as a reason not to repair. The repair company simply said there are too many. How many car owners/customers would trust the word of a professional making such an appraisal and agree to have the whole windscreen replaced? The reality is, it won’t be long before the new windscreen (which would not be a genuine OE part) to pick up similar damage?

There are no ‘windscreen commandments’ forbidding multiple repairs, nor technical explanations (on the repairer’s website) to validate why their repair criteria is set in this way. Incidentally, they also will not repair anything in the windscreen perimeter yet they ‘proudly’ boast a ‘Repair First’ policy. So what’s the issue here? It’s quite plausible for a motorist to need five separate repairs on five separate occasions (which would obviously mean five separate invoices) but why is it that if there are four or five on the same windscreen they won’t repair on one visit?

Granted, some car owners would choose to replace the windscreen, so who decides? The consumer? But what if the consumer decides against it? A new windscreen? Who decides that? The repairer? Who is the real beneficiary here?