Ok, you just bought a huge screen printing kit, put together the press, watched the video, re-watched the video. Now what? Let touch base on a few pointers!
One topic that we encounter on a daily basis is the importance of a light sensitivity environment to work under. It is recommended that you find a space to work in low lighting, try to eliminate any UV light from entering the room. Once you have put together a darkroom of sorts you may consider working under a yellow light, this will eliminate the UV rays and provide you a safe area to prepare screens. Once the screens are coated you now have an active photographic screen! Think of it like its film in your camera. If you pulled the film out of the camera it would be exposed and your pictures would be lost forever!
Most likely you have received a quart or gallon of emulsion, the emulsion sent along with your kit was designed for the application that you will be printing, in most cases it's going to be Tee shirts, some others will want to do signs. In each case the emulsion is different.
Typically all emulsions do the same thing. They provide a smooth layer that attaches or embeds into strands of the mesh, making the screen very tough and durable once it is exposed!
What kind of emulsions are on the market? Several kinds, the first one is the dual diazo, this emulsion is a two part system. Part one is the diazo, that is the part that is a photo sensitizer and usually accompanies the emulsion. To activate the emulsion you must mix water into the small container with the diazo, put the cap on and shake it up, then pour the contents into the emulsion and stir it up, let it stand for about 2 hours, then you can use it!
For general Tee shirts, hoodies and fabric based substrates, we recommend using a dual diazo emulsion because of the wide latitude for exposure times. What does that mean?
Most people who purchase our kits will find out that we offer a selection of light sources to expose screens, if you use a 500-watt halogen and someone else uses exposure unit light box the exposure times will vary, so will your results! So by using a dual diazo emulsion the exposure times donåÕt have to be timed down to the second. Times are not as critical.
Pre-sensitized emulsions are ready to go right out of the gate. Typically these emulsions will expose much faster than the dual diazo emulsions. Screens can be coated a little thicker and its best to expose with a stronger light source and a shorter duration! These emulsions have more solids built into the mixture that will provide more body and will be thicker. These kinds of emulsions are intended for extended runs and are very tough!
When doing signs you will need an emulsion that will stand up the harsh solvents and cleaners used in those processes! They are offered as dual diazo and pre-sensitized formats however they are much tougher and can withstand washout with chemicals or water which may otherwise cause the screen to break down prematurely!