polycarb face snapping in half?

[Bradley D]

Could it be a reaction to the paint? Just had a flashback to when we cleaned a huge Polycarbonate panel with tons of adhesive remover and it disintegrated on the way to the installation. Read the adhesive remover directions the next day that said do not use on polycarbonate.

Sorry to reply to an older thread but I believe Souldar is 100% correct, polycarbonate is subject to crazing caused by several types of solvents and this can be seen also in the substrate guide for matthew's paint. I have sometimes accidentally used acetone to clean a polycarbonate backer for a sign and you will see it get lots of microcracks and completly loose it's stength just upon contact if the acetone touches the area of a nutsert.

 

[Vassago]

As Bradley said - It'll be the solvents its been exposed to - paint, etc.

In these days of "Environmentally Friendly" products, formulations are often changed - so what was OK, might not now be OK.

Might be worth trying a few samples of solvents and see what happens.

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[Niel22]

hey guys- just finished a polycarbonate oval out of 3/16" size 5' by 7' painted with lacryl and grip flex. trimmed with 2
' trimcap with channel bond. While inloading the face literally snapped in half. the masks we used were vinyl meaning we did not cut or score face. Am i wrong in thinking this should not have broken?
the plastic was a very small expense compared to the 6 color paint job. As usual my supply house is blowing me off. doesnt long pieces get rolled up? this was not nearly bent as it gets in the roll. feedback please......

That looks like acrilic look at the edges of it it's to sharp poly carbon bends before any brake can form only if you heat a bend enough to get air bubbles in it will you be able to snap it

 

[JBurton]

I'm a fan of double stick + staples, we used to use channelbond, but found without great application it would leave gaps big enough for the hanger bar to bind on the lip, so you'd be pushing all day swearing in the air.

IDK why I said staples here, I meant rivets. We've also been using some nylon rivets for our marquee track, but I wouldn't recommend them for hanger bar.

 

[Johnny Best]

Here is what I think happened. Since it was an oval it has to be cut. With CNC or by using jigsaw or router. Somehow a small crack or grazed on edge and when channel bond was used it creeped into that craze and cause the cracked face.

 

[citysignshop]

Here is what I think happened. Since it was an oval it has to be cut. With CNC or by using jigsaw or router. Somehow a small crack or grazed on edge and when channel bond was used it creeped into that craze and cause the cracked face.

agreed....machining introduces stresses into the edge. ...and the edge is probably 10x more sensitive to solvents than the hard face. If you sprayed with something other than T2003 or other lexan-approved thinners, that could start the stress-cracks in the edge. Ditto for most glues that are methylene based.
I was taught to always treat faces like they were glass...keep vertical, support when lifting or laying down etc.... I cringe every time I see two guys pickup a long face from each end, rather than at the 1/3 points. ( sigh!) don't they teach these kids anything anymore?