The darkroom is a crucial part of the screen printing process. Everything starts and ends in this space: degreasing, exposing screens, and reclaiming them after a job. Setting up a darkroom for the best screen creation process can be tricky. Here’s a step-by-step guide to getting it done.
STEP 1: IDENTIFY THE SPACE
Every shop’s darkroom is a little bit different. With space constraints, natural light considerations, flow options, and more, there are plenty of factors to consider when setting up a darkroom.
Firstly, a darkroom needs to be, well, dark. Find the best, darkest place in the shop to create the darkroom. This can be a closet, a windowless bathroom, or a sectioned-off portion of a garage shop. Some printers create a darkroom in a larger space by building a separate room with plywood and 2x4s. There are a million and one ways to get creative and find a good space.
Next up, darkroom space. Light-safe bulbs can be added to just about any light fixture. The screen drying rack is an important piece of equipment needing a dedicated space. Getting properly dried screens is vital to the process. If space is limited, create a screen rack shelving system in one corner of the room.
There’s more equipment that needs to be included in the light-safe darkroom. The exposure unit, washout booth, screen coating, and film registration areas all need to be in at least a light-safe environment.
Once the space has been identified, it’s time to start light-proofing it for UV light.
STEP 2: LIGHT-PROOF THE SPACE
Eliminate all sources of UV light from the darkroom. Replace lights with UV-safe bulbs. These are usually yellow or red in color. Block out other UV light from cracks in the doorframe, windows, or other sources of light.
The goal is to make the space as dark as possible so the screen will be in the best shape possible. A closet is a great space for a darkroom since it’s already its own space. Screen printers using a closet to dry screens may not have room for the exposure unit and other equipment in the space. Replace the bulbs in the room adjacent to the closet with light-safe bulbs and use that room as a darkroom.
There are a couple of other factors that contribute to a dialed-in darkroom: humidity and temperature.
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STEP 3: CONTROL HUMIDITY AND TEMPERATURE
Screens dry best when in temps of 75°F-80°F and humidity of less than 45% (ideally under 35%). To keep these conditions optimal, shops in humid climates should set up a dehumidifier in the darkroom space. Shops in Florida, for example, will benefit from having a dehumidifier, while shops in Arizona likely won’t need one to keep humidity down.
Pro Tip: The heat from the dehumidifier may be enough to keep the darkroom warm enough, especially if the screen drying area is small and enclosed.
Good airflow is also important for drying screens. Set a fan up next to the drying rack to create airflow across the screens. Crafty screen printers can mount the fan to the wall if there is space, or create a complete dry box that will have the best possible climate for screens to dry in.
Not sure about the humidity and temp in the darkroom? Pick up a hygrometer. This device reads the humidity and temperature in a space and can provide a history of the space’s conditions over time. It’s a great way to keep the darkroom in the best condition.
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There’s one more factor that many shops have to consider: where does the washout booth go?
WHERE DO I PUT MY WASHOUT BOOTH?
As mentioned earlier, sometimes the darkroom doesn’t have space for a washout booth. As long as the booth is in a light-safe area for rinsing out screens, it doesn’t need to be right next to the exposure setup (though it helps keep everything organized).
Regular light bulbs can be replaced with light-safe bulbs, so the washout booth (and any other darkroom equipment) can be placed anywhere as long as the area is safe from UV light.
A bathtub or utility sink can work as a washout booth as well. When using a bathtub to rinse and reclaim screens, try to avoid staining the tub (especially if you’re renting!). No matter where the washout booth is, filtering the solids and chemicals from the water is key.
Filtration is important in saving a building’s pipes and plumbing from needing to be replaced. A complete filtration system is handy but can come with a price tag. If this isn’t an option yet, printers can create their own.
Use at least 1 screen over the drain of a bathtub or utility sink. Printers can use regular screen printing mesh for this part. If it’s possible, drain the water from the sink into a series of buckets, barrels, or tubs with different sizes of screen mesh over them. This will filter out both large and small particles.
Using a filtration system is just one option printers can create a better environment and save themselves money in the long run. It’s all part of dialing in the darkroom.
No matter the type or size of the shop, creating a good darkroom is important. Remember the three key ingredients to a great darkroom: light-safe, warm, and dry. Follow these tips and use a bit of creativity to dial in the darkroom and create better screens.