April 28, 2015
Researchers:Kevin Pomerleau/ Daniel Chiaccio
Room Temperature: 65 degrees F
Materials: Macdermid Plus 8,000 Universal Resistant Emulsion, 17x 15″ screen, Speedball Screen printing ink with extender, Exposure unit, Opaque Black Trash Bag, 2.5 lb paper weights
Abstract: To see the quality of printed text and a halftone image with Macdermid Photo Emulsion exposed for 5 minutes in exposure unit without a vacuum suction.
Upon receiving the Macdermid Emulsion we carefully mixed the powder form of Diazo Sensitizer into the container of emulsion wearing gloves, masks, and aprons to ensure that we did not come into contact with our skin. The mixing process took place in a light sensitive room, using yellow safe lights (i.e. the darkroom at Zea Mays). We found that using a disposable wooden paint stick worked best when mixing, and we wiped any excess emulsion back into the container wrapped the stick in newsprint, and disposed of it in a covered metal trash in an non enclosed area.
Procedure: After preparing our photo emulsion, we applied it to a 17 x 15″ white 195 mesh count screen using a 14″ scoop coater in our darkroom under yellow safe lights. After letting the emulsion dry for 30 minutes under ventalation, we exposed a premade transparency using both halftone and text (refer to “How to halftone an image in photoshop”) by placing the transparency, emulsion side up, onto the exposure unit with the emulsion coated screen faced down over it. We then covered the entire unit with an opaque black trash bag and 2 paperweights and set the exposure time for 5 minutes. Once the exposure was finished, we removed the weights and trash bag, and walked the screen to the washout booth (in a non light safe room) and washed the screen out.
Conclusions: Using the Speedball Screen printing ink with extender to print, we found that the exposure time of 5 minutes in a non suctioned exposure unit caused the image to lose a lot of detail in the areas which rely heavily on mid tones, leaving us with a final print consisting of only deep blacks, stark whites, and no grays. We concluded that the loss of detail might be due to the emulsion not drying long enough on the screen before being exposed, thus causing the gray areas of the screen to blow out. For test number two we will increase the drying time of the emulsion-coated screen before exposing it, in hopes of gaining more detail in the final image.