Most alternative photography methods of printing require long exposures to an ultra-violet light source. In the 19th century the Victorians used the sun and you can see from the many images on the internet and in books that the sun works fine. You can even tweak the contrast. Extending the exposure time by printing in the shade gives more contrast than exposing in direct sunlight. However, in the UK, the sun is a little variable so an artificial light source is preferable. Artificial light sources also have the advantage of giving consistent results. There are two options for artificial light sources, commercial units and homemade units.

Commercial units tend to be very expensive from many hundreds to several thousand pounds although you might strike it lucky and find something secondhand. Older plate burners employed in the graphics arts industry crop up from time to time at a fair price. However there are disadvantages to these machines. They are extremely heavy and take up a lot of space. The bulbs are difficult to source and can be very expensive, costing as much as £200+. Many graphic arts plate burners, such as those made by NuArc, include a vacuum bed. This removes all the air from between the negative and sensitised paper preventing soft, out of focus areas. A vacuum bed is particularly useful when make very large prints, where a printing frame may not give even pressure over the surface.

A flourescent UV unit designed for alternative photography from https://cyanotype.co.uk/

Most modern commercial units, such as those used for making PCBs or screen printing, use fluorescent tubes and LEDs. If you were to go down this route try and find someone who has used the particular unit you’re interested in for alternative photography or use one designed for alternative photography. I once had a 20”x24” fluorescent bulb exposure unit designed for screen printing but it had very slight uneven illumination. The bulbs were too far apart resulting in areas of slightly different density. An expensive mistake!

My first UV unit was made from two Philips facial solariums. I took them apart noting the wiring and reassembled them in a homemade box. At the time I was finding these tanning units at car boot sales (yard sales) for £5 or less. I ended up making four units, useful for teaching. The tanning units turn up on eBay regularly but they’re very expensive so check car boots and charity shops.

In recent years UV emitting LEDs have been available. Two designs that are available are units using LED strips (tape) or those similar to floodlights. The floodlight types generally emit longwave UVA light at 380nm – 400nm.

The LED tape is suitable for making your own exposure unit which I recommend. LED tape is available in different wavelengths. The cheapest is 380nm - 400nm. You can also buy 365nm tape but it’s very expensive. A basic LED unit can consist of LED tape, a power supply and a switch. My unit is a little more complicated having two timers installed. I also used 365nm LEDs which I sourced from Aliexpress.

The internet recommends that the LED tape is mounted on an aluminium sheet with the addition of fans to keep the LEDs cool however my LEDs hardly get warm but it’s better to be safe than sorry!

UV Exposure Options