Glass exploded with perforated film – advice please?

[David Rogers]

Depends on the print. If it’s dark or black then it’ll absorb and transfer the heat regardless of the perforated media.

[Lionel Hermans]

Hi David,

It is indeed dark but that’s why we use perforated film, on top of it is placed on the outside.
What should I use then ?

Thx,
Lionel

[Phill Fenton]

Just a thought – but if the vinyl was trimmed to size on the glass, could it be that this left a scribe mark on the surface which may have caused the glass to fail?

[Lionel Hermans]

quote Phill Fenton:

Just a thought – but if the vinyl was trimmed to size on the glass, could it be that this left a scribe mark on the surface which may have caused the glass to fail?

yes the vinyl was trimmed but the glass is about 1.5cm thick so … I don’t think a metal cutter cut can do that.

quote David Rogers:

If it’s dark or black then it’ll absorb and transfer the heat regardless of the perforated media

We mesured the temp difference, indeed the dark is about 15 to 20 degrees hotter than the white … but what makes a window explode is the gaz temperature inside the double glazing, not the window temp itself. It can go up 90°.

[David Rogers]

It’s not really the temperature it experiences but rather the different thermal stresses due to its low toughness & thermal conductivity and high thermal expansion.
Glass thermal shock happens when different parts of the glass expand by different amounts. When the stress overcomes the strength the glass either the external pane will explode due to the heat pressure build up, or more commonly the internal pane will crack. Weak points from minute imperfections in the edge cutting will just get stresses too much. it’s not actually the gas pressure.

Today it may have been 15 degrees – but on a hot day / direct sun the difference between white & black areas could rise to over 40 degrees…it expands, the white doesn’t and you get massive forces at a molecular level – totally unstoppable.

Only toughened or tempered glass has a chance – normal glazing not so much. There’s no way round it except very light designs.

[Lionel Hermans]

Thanks David for that reply!

CONTRAVISION will send his representative to check the windows. They told me they are 200% sure that’s not the vinyl.
To be continued …

Lionel

[Jinty Burke]

OMG I’m putting window vinyl on a chip shop in a few days. It’s the first time a customer has actually asked me to install the stuff instead of just cutting and designing it. I’m not too happy about putting it on but now I’m dreading it! Any advice? I’ve done vans/lorries/cars, etc. galore in the past but never windows. The stuff going on is window vinyl and each window and door will have one LARGE DARK BLUE graphic on it?

[Simon Worrall]

Make up a disclaimer and get the customer to sign it BEFORE fitting, Jinty

State the possibility of cracking specially if the window is not toughened and gets direct sunlight etc.

Simon.

[Tim de Beir]

Hi Lionel, looking at the cracking i am pretty sure that it is thermal issue!!
Was was stored in the interior sp behind the glass? This can also be an issue…

[Jinty Burke]

Thanks Simon. I’ll do that if I can’t sort of knock something off the invoice and let him think he’s getting a real bargain if he fits the stuff himself! Wish me luck. 😀

[Lionel Hermans]

Just a little update about the issue.
My supplier came to site the do a visual check on what was going on, and a couple of days later a tech representative of Contravision (the manufacturer – contravision.com) came from Netherlands too … What a customer-service! 🙂

Of course my customer was impressed … and here is what they (Contravision) said :
– 200% sure it is NOT a thermal issue
– 200% surr microperforated film doesn’t explode windows
– Black part of perforated film can quickly go up in temp but not enough to explode a window
– Thermal explosion goes from top to bottom (vertically), in my case the window have cracks from left to right (horizontal)
– Problem should be window placement (too much tension)

On the other side of the street (apprix 100m) there was some building construction, and they made some fondations at the time the window cracked. It’s was the cause of the explosion, this caused some micro vibrations and the window didn’t moved enough due to film on it (all was covered).

Hope it helps …

[David Rogers]

I thought some of the facts sounded odd, and frankly a bit unbelievable such as always vertical cracks and no way it can make it crack.

So I took a guess that a glass manufacturer such as Pilkington might know a bit more about glass than most people.

https://www.pilkington.com/resources/at … 050713.doc

Interesting read about the small temperatures and massive stresses involved.

Dave

[Michael Kalisperas]

Wow proves you learn something new everyday. I find it hard this happens. I mean we have had heatwaves and the same glass especially that thick can be found in countries around the world where there is soooo much heat. I’m shocked if this is the case!!
I wonder if its pressure During the application period. I would assume a small chip hidden in the rubber area the glass slots into. I’m in utter shock this can happen!!
Wow tell me I’m dreaming and I’ll wake up in the shower with the last job all fine 😉

[Michael Kalisperas]

quote Jinty Burke:

OMG I’m putting window vinyl on a chip shop in a few days. It’s the first time a customer has actually asked me to install the stuff instead of just cutting and designing it. I’m not too happy about putting it on but now I’m dreading it! Any advice? I’ve done vans/lorries/cars, etc. galore in the past but never windows. The stuff going on is window vinyl and each window and door will have one LARGE DARK BLUE graphic on it?

Don’t worry it