uvb tubes, harmful?

[Arcadiajohn]

All glass, acrylics and plastics are a 100% UVB stop even at source unless a uv transmissive material is used like optiwhite which still only let's through about 40% for a short distance.

White glass from commercial viv doors are a UVB stop.

It has just taken us almost 10 years to to develop an injection moulding acrylic that is uv transmissive for the D3 arc-pod.

John

[Merlin M]

I work within the conservation part in museums, and light is a major factor as it damages collections, particularly UV. I have seen for myself using light detectors that standard glass does allow some UV through, although its intensity drops sharply withing the room. If glass did not let through UV we would not put UV filters on the windows in museums and historic houses. this UV stops being a problem after about 1m but my point is that it is still coming through the glass.

Now I made a general point about glass without UV filters, for all I now viv glass has UV filters in it I don't know, but standard glass does allow some UV through, not enough to damage our skin in the short term (ie sunburn) or damage our eyes but enough to fade and damage wood, textiles and paintings.

Also if glass let stopped all UV then people wouldn't make sure they got sunglasses with a good UV filter in them!

[mattb]

Hi guys,

This is all very interesting stuff.

In response to questions.
My optometrist has only very recently semi diagnosed Kc. He said that there are several factors which point toward me having it, my eye shape, the fact it seems i have fluctuating vision, and that i also have eczema which apparently increases my chances of having it.
Im going to be referred to a specialist (at hospital) to check it out completeley, but so far no advice in terms of sunglasses etc. just to wear the prescribed glasses. Apparently my eyesight is still very good (with glasses) and he thinks the Kc is very early stage, if it is Kc.
It mainly just got me thinking that ive noticed my eyesight degrade the last 6 months to a year, which is the same time ive had my tort lamp for. But as Arcadiajohn has said i know that it is mainly a genetic condition.

Thanks for the black guttering tip, i may well put that over the reflector.

Cheers,

Matt

[Ozric Jonathan]

Merlin clearly knows a great deal more than me about the effects light has in a museum environment. But I am not sure just yet. I say that because I've got a solarmeter which is said to be really quite accurate and in my house it detects no uvb coming through the glass into the room. This includes having the meter right up to the glass. Of course I don't know what exact glass is in the Windows. Maybe it lets in uva?

I've got an alltop plexiglass enclosure which does let in significant uvb. This material is expensive and over time degrades and gradually lets less and less uvb through even though it was specifically developed to transmit uvb.


In relation to Matt's question I think the uvb reaching his eye from the tube is negligible unless his eye was very close to the tube since it doesn't travel far from the tube.

[Merlin M]

Originally Posted by Ozric Jonathan

Merlin clearly knows a great deal more than me about the effects light has in a museum environment. But I am not sure just yet. I say that because I've got a solarmeter which is said to be really quite accurate and in my house it detects no uvb coming through the glass into the room. This includes having the meter right up to the glass. Of course I don't know what exact glass is in the Windows. Maybe it lets in uva?

I've got an alltop plexiglass enclosure which does let in significant uvb. This material is expensive and over time degrades and gradually lets less and less uvb through even though it was specifically developed to transmit uvb.


In relation to Matt's question I think the uvb reaching his eye from the tube is negligible unless his eye was very close to the tube since it doesn't travel far from the tube.

i don't know what the split between UVA and UVB are that glass lets in, as we were just looking at UV, in conservation it makes little difference... It still damages and that is all we are concerned with, we also use perspex with UV filters to prevent damage.

But the intensity on any UV drops of quickly as you more away from the source, so the UV tubes should be ok unless you are close to them

[Alan1]

As I pointed out elsewhere, UVA gets through glass in vehicles and will damage the skin. I don't know if it damages your eyes but I wouldn't want to test it out