Exposing Screens with the Mineral Oil Technique
I have been wanting to try out the screen printing mineral oil technique for a while now, which uses mineral oil (baby oil) to make a normal sheet of paper transparent enough to expose imagery to a screen coated in photo emulsion. This is similar to the process of using imagery printed on transparency film but I have always been skeptical about whether it could work for fine details. It just seemed like the level of transparency created by the oil would not be transparent enough to allow exposure of fine detail work.
To test this, I used a half-tone filtered image to test whether this technique can work for exposing details. To my surprise, the technique actually worked really well. Below are a few images and an overview of the steps I followed.
Materials:
Screen (prepared with photo emulsion)
Exposure light (I use a yellow utility light)
Image printed on standard printer paper in black ink
Baby Oil (Mineral oil)
Small container to hold oil
Medium-sized paintbrush
Glass from a picture frame (optional)
The Process:
Step 1: Get your screen prepared with photo emulsion. (I did this the night before)
Step 2: Print imagery using a home printer on regular white printer paper.
Step 3: Prep materials. Put some baby oil in the small container and prep the work area. I want everything in the work area prepped, so the screen is only exposed to ambient light for a short time before exposure.
Mineral oil technique work area. The image on the right shows the paper becoming transparent as the baby oil is painted on the back of the sheet.
Step 4: Bring the screen out from the "darkroom” and place it within the work area. (My current darkroom is a large sealed Rubbermaid container where I store screens while drying)
Step 5: Position the print on the screen with the ink side touching the emulsion. The backside of the paper should be facing out.
Step 6: Paint the baby oil across the back of the paper, aiming to smooth out any bubbles that occur as the paper is moistened. Work quickly to cover the entire image evenly.
Step 7: Now, you are ready to expose the screen. I placed a piece of glass over the image because I noticed a few areas of the paper bubble up. This is optional, but I have typically used this technique with transparencies, and just gives me a little more confidence that everything will stay in the same position during the exposure.
Step 7: Expose the Screen
Step 8: Wash out. Follow your normal process for rinsing out the image.
Voila! When I first saw the bubbles during exposure, I definitely thought this process would not work, or that there would be a few areas exposed incorrectly. However, as the image rinsed out the exposure looked surprisingly consistent.
Quick test print
Overall, the method was quite forgiving and is a great option even for detailed imagery.