Exposing screen:

So, you take your dried screen and you place the image on your screen, then you expose the screen to your UV light source.  The UV light will then harden the emulsion.  What the paper image does is block the light, preventing the emulsion behind it from hardening.  Once the screen is done you simply wash out the unhardened emulsion.  With this process you are essentially creating a stencil.  Where your image was will allow ink or paint to be pushed through allowing you to print your image on anything. 

When your emulsion is dry on the screen before you expose it, it will be a bright green.  Once it has been exposed to the UV light it will become a darker, duller green.  The area of the image you are burning into the screen will still be that first bright green color.  You don’t want to dilly dally before you wash the image out because that emulsion where your image is can still be exposed. 

For me, once the screen is ready I use my exposure unit to expose the screen.  You can you the good old fashion sun if you not have access to one.  It only takes about 30 seconds for the sun to expose a screen but you have to reverse you image and cover it with glass so it doesn’t move.  This has to potential to not be 100% reliable each time.  So, I stick to my expose unit.

I can use a photo copy of a black and white image and then I saturate the paper in baby oil to make the white part of the paper transparent.  This allows me to get as detailed as I want.  You have to use a laser photo copy and not a print out from an ink jet printer because the baby oil will make the ink run and ruin your image.  With this particular print I am actually using a hand drawn image that I did in sharpie and then baby oiled to rest of the paper, that works too if you are trying to get a hand drawn feel to it.

I take my image and lay it face up on the glass of my exposure unit.  I position my screen onto of the image and then weigh it down with something heavy so the screen lies flush against the image.  I then cover it with a couple blankets to block out all the light from coming in and to keep the UV light contained in.  After it is ready, I turn on my exposure unit and let it do its magic. 

Now, not all screens are made alike.  Each screen can use different mesh material that has a different thread count.  You want a lower thread count for things like tshirts or printing on fabric and you want a higher thread count for fine art printing. The sad thing about having different types of screens and mesh is that not every screen takes the same amount of time to expose.  There is a period of trial and error at the beginning of this.  I have it pretty much figured out with all my existing screens take about 25 minutes to expose an image.