20"x24"UV Exposure Unit Exposure Unit is an important tool in screen printing because screen exposure is one of the most important steps to the screen making process. This 20"x24" table top exposure unit combines affordability and quality. With this unit you are able to burn crisp images and bring a professional look to your screen printing shop. The built in automatic timer helps achieve a perfect exposure effect. Working principle: screen printing screens are coated with a light sensitive emulsion using a scoop coater. When the emulsion is dry, place a positive print of your image on the screen. Once you burn the screen, the emulsion that did not get any UV will wash out of the screen exposing the tiny pin holes. The surrounding areas that were exposed to UV will be cured. Hence the ink will pass through screen onto your substrate. Item include: 1 set 21x25 inch LED exposure unit --- 006854 Note: The maximum external size of your screen frame must be within 25" x 21"x1.5" (64*54*3.8 cm). If exceeded these sizes, our exposure unit cannot be covered well, which will affect your exposing effect.