uv exposure diy boards

I'm still working on my uv box... anybody have any recommendations how far away i should place the leds from the glass surface? or should i do some initial testing? thanks :)

If you have a datasheet of the LEDs you are using, they should say something about the focus of the LED. An angle in degrees would be helpul, as you can use it to calculate the covered area of one LED, at any distance.

i got the leds on one board done... but the board gets a little hot!!!