To choose a standalone UV lamp for cyanotype, look for UVA, often labelled BLB or black light, at around 365 to 400 nanometres. Then check its power, the area it covers and its distance from the paper according to the size you want to expose.
A basic lamp sits above the print: a screw-in bulb, a small LED panel or a tube, which you set up yourself. It lets you work in bad weather or in the evening, on a modest budget, for small formats.
The choice here concerns the standalone UV lamp, its power and its use. The comparisons with a UV exposure unit help you spot a lamp's limits for series and large formats. If you are new to the process, the cyanotype guide lays the groundwork before you choose your equipment.
Choosing the lamp’s format and wavelength
The ultraviolet source is just one item among the cyanotype supplies, alongside the salts, the support and the rinsing tray.
The basic UV lamp is a bare light source, a screw-in bulb, a small LED panel or a tube to set down, which you install yourself above the paper. It is the lightest purchase, often a few tens of euros, and the most adaptable, since you choose the power and can move it as you please.
The UV exposure unit, a finished product
The UV exposure unit is a finished product, a closed box that combines several UV tubes, a contact glass and, more often than not, a timer. You are paying for a designed and calibrated whole, so it costs considerably more, but it arrives ready to expose with nothing to assemble. The price gap reflects two philosophies of buying: the minimal tool you complete yourself versus the complete piece of equipment you simply plug in.
Before any purchase, there is one point to check on both: the wavelength. Cyanotype reacts to UVA, at around 365 to 400 nanometres, and that is the specification, often labelled BLB or black light, to look for on the product page, whether for a standalone lamp or a UV exposure unit.
How much each option costs
A basic UV lamp remains the entry-level option for cyanotype without the sun. A UVA bulb that screws into an ordinary socket, or a small LED lamp sold for drying nail varnish, can be found for a modest sum and is enough for small prints. A wider UV LED panel, covering a whole sheet, costs a little more but stays within a modest budget.
A shop-bought UV exposure unit plays in another price category, because you are buying the casing, the tubes, the power supply, the glass and the timer all in one. The outlay is justified when you print often, much less so for an occasional try.
Between the two there is a middle way: building your own casing around UVA tubes bought separately, which brings the cost of an exposure unit down towards that of a basic lamp, at the price of a little assembly.
The power you are really buying
The price pays first for the area covered and for evenness, not for speed. A single UV bulb lights a postcard-sized area well, but its edges weaken as soon as you enlarge the format, whereas a multi-tube exposure unit bathes an A4 or A3 sheet in even UV right into the corners. Buying too small for your formats is the false bargain that forces you to start again.
Next comes consistency. A basic lamp positioned by hand is only roughly put back in the same place from one session to the next, which is enough for experimenting but makes it harder to reproduce a print exactly.
The consistency of a UV exposure unit
A UV exposure unit fixes the distance, the arrangement of the tubes and, with its timer, the duration to the second. It is this consistency you are paying for, valuable when you print in series or teach, incidental for leisure use.
One point to watch on both: UVA tubes and LEDs lose intensity with use. A basic lamp can be replaced for a few euros, whereas on an exposure unit it is best to check before buying that the tubes are a standard size and easy to buy again.
Checking the space available for your sheet, with the unit switched off and unplugged. This generic UV exposure unit does not represent a commercial model.
What to buy for which use
In workshops, buying advice always comes down to one question: how often, and at what sizes, will you print out of season? To help out now and then, finish a print on a winter evening or have fun with small formats, a basic UV lamp is the right purchase, inexpensive and quick to put away.
Place a single UV bulb about ten centimetres from the paper, and a wider panel or tube between fifteen and twenty centimetres away.
Under a UV lamp, allow from around ten minutes with a powerful panel close to the paper to three quarters of an hour, or even longer, with a simple low-power bulb. It is worth knowing how to use it, at what distance and for how long, before you choose its power.
When a UV exposure unit pays for itself
For regular practice, repeatable series or large, even formats, the exposure unit becomes the investment that pays for itself, because it provides the coverage and consistency that a lamp alone cannot.
And if budget matters but the need is serious, a home-made build around UVA tubes bought separately offers the most sensible compromise, provided you accept a little DIY. If you need a complete casing, the UV exposure unit remains the long-lasting piece of equipment, to choose or to build.
- Small formats and occasional use: a basic UV lamp.
- Regular practice, series and large formats: a UV exposure unit.
- Limited budget with a regular need: a home-made casing around UVA tubes, if you accept the assembly.
Before buying a UV source
One last reminder before spending anything: the sun is still free, powerful and more than enough for discovering cyanotype and printing through the sunny days. The question of buying a lamp or an exposure unit only really arises when the weather or the time of day holds you back, or when consistency becomes a real need. Many practitioners print for years with the sun alone without ever buying a UV source.
To practise before investing, the Sténoflex cyanotype kit and its ten sheets of suitable paper let you test exposure in the sun as well as under a lamp and pin down your real needs: formats, frequency, consistency. Once that need is clear, the right purchase is the one that matches your practice.
Éric Marais — Photographer, author of two books on pinhole photography (published by Pearson) and creator of the Sténoflex. He has run introductory workshops in alternative photography, from pinhole to cyanotype, from the very beginning.