It should not block UV. That is the biggest issue with glass.

 

Also use table glass, the edges are beveled and smoothed so you won't cut yourself and it is heavy enough to stand a lot of pressure. I've used a unit with just standard glass and it came apart.

 

Tempered for sure.

 

when you go to the glass place they will/should what you are using it for and they will/should smooth the edges for you.

 

I used tepered because of the risk of breakage , tempered breakes in tolittle pices regular glass breakes into slivers.

 

exposure unit manufacturers do not recommend tempered glass from what I remember . . . they never really specified why, but when shopping for replacements for the expensive exposure units, they will tell you to stay away from tempered.

As somebody already said, make sure it does not have any UV blocking coatings or films.

I would also stay away from anything too thick, it will make your exposure times longer.

 

I would also stay away from anything too thick, it will make your exposure times longer.

Table glass is 1/4" thick, with 8 UV florescence tubes about 2" under it on 3" centers I get solid exposures at 2 min. 45 seconds.

 

Blue Moon is Correct. Non UV, and Non Tempered Glass. I bought 1/8, and Non UV, and Non Tempered.

The local glass supply beveled and smoothed the glass for me. I gave them the wrong size, and since it was larger than I need they said they will re-cut for free.

 

Just ask when buying from glass store if you can get the glass without uv filter.

 

John of ShirlandDesign, The Flourecent Tubes are normal Flourecent Tubes? I think I have six. I still need to take my glass back to the Glass Supply to have them cut the glass to the right size, but sounds like I'm in the ball park.

 

no, they should be UV tubes!

 

Standard 1/4" float glass. Plate glass and tempered glass cost more. Ask them to sand the edges.
I bought a piece of "low iron" glass called Starfire, hoping to decrease exposure times, and I can't say that it helped. It's the iron in plain glass that allegedly inhibits UV, but even my store-bought MH unit specifies plain 1/4" float glass as replacement.

 

They are UV florescent tubes I got from Pet Smart, they are normally used for reptiles to sun under.

 

Thx John, I'll check that out

 

Thanks for the info.....Really helps As I am building my own exposure unit as well

 

Hi guys, I'm using a 500 watt halogen spotlight for the porch. I have removed the glass from the light for better UV penetration . Right now, i needed a glass for putting on top the film. My question is , How can i tell if the glass i took back from the glass store wasn't a filtered UV glass. Any way or indicator that could establish the facts?
thanks.

 

None that I know of. Ask the Glass shop you bought it from.

 

i may ask him but i would like to know how he could tell if the glass is non filtered UV? Is it by seeing the texture or some device testing?

 

EB Forum • View topic - How to tell if glass is UV?
found this , i guess it answers my question. if u know anything different , let me know. thanks guys.

 

Yeah... I doubt you're going to get museum glass from your local supplier unless you pay a whole lotta money for it.

Simple answer:
clear edges=low iron=high UV transmission
green edges=high iron=lower UV transmission.

As was previously mentioned, you may want to think about whether or not it matters if you get 70% UV transmission or 90% UV transmission for three times the price.

 

Sound so simple. A Clear glass is purely glass without any sort of coat as you mentioned. That itself indicates unfiltered glass, am i right?
thanks for answering noob question.

 

No prob--you may have missed what I was getting at though.

The cheaper stuff is not "coated", there is iron throughout the composition of the glass that absorbs UV.

The cheapest stuff will work fine, and is in most gear anyway.

 

I bought glass for my new unit yesterday and the chap said you dont want to use tempered glass as it can refract and bend the light when it goes through it.

cheers

 

You can also Barter for the glass. Offer to make them some t-shirts or other products they'll need.

 

i know this an old post but your saying 1/8" is good enough?..im trying to get 3/4" but all the local shops only have 1/8"

 

3/4" is way too thick. Do you mean a 1/4" that would be okay. You need to have the edges beveled. Also if you can get the Non-green glass. If you can't don't worry about it.

 

Ask for 1/4 clear annealed. If a glass shop does not have 1/4" clear I would be very surprised. This is standard glass and will probably start at around $8.00 per square foot.

If you dont want the edges to be fancy ask for an eased edge. Most glass shops do not charge for this. The edges are simply sanded to remove the sharp edge.

If you want a uniform edge that looks nice ask the shop what they do in house. Pencil edge. grey grind etc.