Styrene Glazing Question

[vintage frames]

This is for a budget job.
The frame is big - 1000 mm x 980 mm.
I'm laying it directly against an inexpensive photo print - a collage effect, and backing it with two sheets of 5 mm foamboard.

Would I get away with 2 mm styrene or is it better to use 3 mm?
What could possibly go wrong?

[JFeig]

With 2 mm vs 3mm styrene glazing and not knowing the strength of the moulding, I would be worried about the glazing bowing.

[vintage frames]

Good point.
In this case the frame is very sturdy. I'm thinking that if the package is pressed firmly against the rebate then there should be minimal risk of the 2 mm styrene bowing.
I've never used the stuff before so I was hoping others might have more experience.

[Justintime]

I posted a reply yesterday but it's not here...
It's the expansion and flexibility that you have to bear in mind. Styrene/acrylic expands and contracts with heat change. There are graphs and charts for this, maybe JKX has some to illustrate. Locking it into place won't solve the issue. It needs the physical strength not to bow with gravity, say when its carried upside down and room in the rebate to expand say 2-4mm. I've always used a fillet/slip to expand the rebate to allow for extra expansion.

[Justintime]

If the expansion gap isn't enough it will pop itself out of the rebate.

[vintage frames]

Interesting point about the expansion tolerance.
I shall check the size of my rebate.
Thanks Justin.