whats lexan ??

lexan is a polycarbonate its like plexi glass it also has a uv filter on one side of it and its used as a heat shield in our projectors since tempered glass is expensive to have it cut then tempered in custom sizes the lexan xl10 can be cut with a utility knife.

Make sure you buy Lexan XL10, it has a UV filter built in. I wouldn't call it a replacement for tempered glass though.

How come ?? isnt it just as good especially with built in UV protection

Speaking of Lexan & UV filtering - I bought the UV sheet (at leaste I assume that's what it is, just looks like an old overhead transparency to me ) from LL along with the lamp set up and lenses. But after reading about a lot of folks using Lexan, I picked up a sheet of that instead of going with the tempered glass. What I'm wondering is, should I use the UV filter with the Leaxan? Is there any advantage or disadvantage in doing so? I figure I already bought the filter, might as well use it if it helps, but don't want to cut down on light transfer or anything else that might degrade the picture. And lastly, my UV filter sheet has a few small "bumps" in it. Think that will affect the picture?

I wonder that too. I know that isn't much help but I am curious. I hear that glass will turn yellow over time.

You certainly COULD use the UV filter, though it will cost you a couple of percentage points in light.

If you are not using the XL10 Lexan, you will still need to. The UV filter protects the fresnel lenses, and the LCD display from being damaged by the UV light. However, correctly using the XL10 will make the UV filter unnecessary.

Tempered glass is still superior to the Lexan, it will withstand a failure of the cooling system, for example, which the Lexan will not. Also in the event of a catastrophic bulb failure (there's videos around here of bulbs exploding) the tempered glass will do a better job of protecting your lenses and LCD.

I had originally bought tempered glass, but due to a complete failure on the part of the glass shop to provide a piece with square corners (4 corners, only 1 was at 90 degrees!) I've switched to Lexan.

Lexan is one of the most awesome things to "see in action" (not in this application though. It's been around for more than 50 years.

I don't know much about it technically speaking, but I know at least one of its uses...

One major industry we cater for at work is Forestry & other heavy industries like Mining etc. For a long time now they haven't used glass for windows on the cabins, they use Lexan.

Long story short... There's tonnes of accounts of where a 500+kg (1100+pounds) tree fell the wrong way when processing/handling it and it came straight at the operator's cabin... what happens...? It hits the lexan hard enough to bend the steel cabin & make the window almost tickle the operator's face - then it bounces back throwing the tree off into the bush... doesn't shatter, doesn't split (if installed correctly)... but it does get all bent out of shape, as you'd expect.

The cons:
Damn expensive.
Any decent scratches & it needs to be thrown out (in case it's created a weakness).
Once hit properly, needs to be thrown away.
It's soft as... you could almost scratch it with ya old fella.
There's more that I can't think of just now.