When most people hear the word darkroom, they immediately imagine a small dank space void of all light. Fortunately, the darkroom needed for screen printing is not this at all and can in fact be the same space you print in if proper care is taken.
Blocking UV Light
The need for a darkroom is based upon the UV sensitive nature of the emulsion that is used to create the stencil on your screen mesh. The emulsion is exposed to high amounts of concentrated UV light during exposure and is hardened to a solid state in the process. Because UV rays are around us all of the time, it is important for us to create a UV safe environment or “darkroom” in which we can work with the emulsion prior to the exposure process.
Creating a UV safe environment is much easier and less expensive than one might think. Unlike photographic darkrooms that require total darkness, screen printing darkrooms only require that UV rays are filtered out of any light source. UV rays are filtered out when light passes through a semitransparent colored object like a piece of film or a tinted bulb. Red and yellow are the most common colors used for the purpose of filtering UV rays but many colors are effective in achieving UV filtration. UV safe bulbs and UV blocking films are readily available and relatively inexpensive.
Note: *DO NOT USE BLACK LIGHTS AS THEY WILL ACTUALLY ENHANCE UV RAYS AND WILL EXPOSE YOUR SCREENS.
With the inexpensive items listed above, almost any space can be turned into a darkroom sufficient for screen printing. By simply covering any windows or other openings that let a significant amount of light in with UV filtering film, the UV rays will be filtered out and will leave you with a well-lit UV safe environment in which to work. Another option is to block the light out all together by using an opaque covering to make the room totally black. If you choose this method you will want to install a red or yellow light bulb into your room so that you will be able to see what you are doing while maintaining a UV safe environment.
There are of course more complex and expensive ways to create a darkroom and as printers grow they will often move in that direction. However, for the beginning printer the methods listed above are tried, true, and cheap. Remember that most emulsions that you will use have an exposure time of multiple minutes under intense UV exposure, so a few seconds of exposure to a low source of UV probably wont ruin or even affect your screen.
Controlling Humidity (Wet Room vs. Dry Room)
Due to space constraints, many people will include their drying and washout areas into their darkroom. While this does make things easy by eliminating the need for multiple UV safe environments, it can also present some challenges. The most obvious contradiction with washing and drying in the same room is that you are introducing moisture to an area where you are also trying to remove moisture. This will not necessarily ruin you, but may make things a little more difficult overall.
If you do decide to coat, dry, clean and washout frames in your darkroom, make sure you have the right tools going in. A dehumidifier is a great thing to have around especially if you are in an environment known to have high humidity anyway. If you do decide to purchase a dehumidifier, make sure that it pulls water out of the air and deposits it outside of your darkroom. Many small dehumidifying units have an onboard reservoir that actually holds standing water in the very area in which it is supposed to be removing it.
A drying cabinet is another great tool to consider. Drying cabinets have built in fans that allow air to move around the wet screen. This creates an ideal environment in which the screen can dry. Most drying cabinets also come with some form of filtration system as well, so dust and other particles on your screen should not be a problem.
Considering the tasks that you will be performing in your darkroom and ensuring that you have the tools to perform each task successfully is all that you will need to do to make sure your darkroom works for you. Proper workflow and project management will help you avoid conflict between tasks and should save you time and money.