UV light is invisible to humans.  It is high energy light that can change things, sometimes to our detriment.  Many of the plastic things we use can disintegrate if left outdoors because  UV light from the sun degrades the plastic.  We get sunburned if we over-expose ourselves to solar UV.  UV is UV whether it comes from the sun, from an electric welding arc, or from a UV lamp or any other source.  There is much research data on a multitude of problems – not just sunburn – that can result from over-exposure to UV, whatever its source.

It used to be thought that Short and Mid Wave UV (UVC & UVB) were the harmful ones, and that Long Wave (UVA) was relatively harmless.  It is now thought by some researchers that UVA may not be as harmless as previously thought, despite the fact that unprotected BLB or “Black Light” UV lighting is used in public areas all over the place, especially in “Discos”, clubs etc. 

Therefore, given that our whole hobby is based on UV light, we have to take necessary precautions against its harmful effects.  We need to protect ourselves, and we need to protect others.

Protecting Yourself

Brief unprotected exposure – less than a minute – is probably not a problem. But be sure never to look directly into a UV light without eye protection.

For extended exposure, you should always protect your eyes from all UV wavelengths.  Clear polycarbonate safety goggles available from any hardware or tool shop will block SW and MW.  You should make sure the goggles can block light getting in from the sides.  Ordinary glass or plastic spectacles will block SW and LW coming straight at your eyes, but won’t block it getting in from the sides.  Proper UV blocking spectacles are best, but are more expensive. 

Skin protection is best achieved by covering your skin with suitable clothes and gloves.  50+ sunblock also works, but be careful not to get it on specimens because it can fluoresce and interfere with the mineral fluorescence.

Protecting Others

Be sure you don’t hold a portable UV light in such a way that other people can look directly into it.  They may not know they shouldn’t.

The main precaution you need to take is to prevent exposure to UV when people are looking at your collection.  If you have a Display Lamp suspended over your rocks you need to make sure people can’t look into the lamp.  You can do this by pointing the lamp away from where people are when they are looking at your rocks, or you can erect a UV-blocking screen.   If your collection is in a display cabinet, there must be a screen or window at the front of the display.

What materials can be used for safety screens?  I will discuss four.

1.  Ordinary glass. This will block UVB and UVC, but will allow UVA to pass through.  Some types of glass are completely unsatisfactory because the glass itself fluoresces.  Looking at fluorescing minerals through fluorescing glass is like looking at them through a very bright fog.  Some types of glass fluoresce if you have one side facing the UV but not if you turn it around and have the other side facing the UV.

2.  Crystal Clear Vinyl.  This works well, blocking MOST of the UV.  It is inexpensive, and is purchased by the lineal metre off a roll.  It comes in various thicknesses – the thicker you use the more UV it seems to block.  It is the stuff used for flexible windows on boats, in tents, and often for weatherproof verandah blinds.  Whilst it is fairly non-distorting, it does not give as good a view as does acrylic sheet.  You can get it from Bunnings-type stores, or from marine supplies places.

3.  Ordinary Acrylic Plastic.  3mm thickness is fine.  This will also block UVB and UVC but not all the UVA.  It works well, looks good, and gives a very true undistorted view of the rocks.

4.  Acrylite OP2 or OP3 Museum Grade Acrylic Plastic, 3mm.  This is the best, and is used by all professional collectors.  It blocks all UV, and so is the safest.  Because it blocks UVA, people’s clothes don’t fluoresce, and all their attention is on your fluorescing specimens.  It is what I use.  As you would expect, it is also the dearest.