My First (and last ?) Photo Emulsion Silk Screen Using Sunlight

Until now, I have only done freezer paper stencils with fabric paints, and let me be the first to tell you that cutting out intricate details is a royal pain.  Photo emsulsion screen printing is like making a stencil right on the screen, no cutting required.  Or like making a negative on the screen, for those of us who remember 35mm film :)  My first attempt didn't go so well, but I'm close to figuring it out.  If you're interested in screen printing, make sure to read at the end of this post where I share some other screen printing options to consider.

Here is the big picture, nutshell, explain-it-to-me-like-I'm-a-6-year-old version:
You put this green stuff on the screen, and when it's dry you put a transparency with your artwork on it. Then you expose it to light and the green stuff hardens everywhere EXCEPT where the black lines of the artwork block the light. The green stuff washes away where the artwork was, leaving you with your stencil (negative)!

Here's the step by step...
First you'll need to prepare your artwork with Photoshop, Print Shop, Word or whatever.  If you have a laser printer and transparencies, you can print them yourself.  I don't, so I emailed the image to Staples, but when they printed them it was very pixelated and smudged looking (odd?).  Luckily, I brought the image that I had printed on my inkjet, which they photocopied onto transparency and it was crisp and perfect.  I had 3 copies made because you need the artwork to be super black to block out the light.  FYI Transparencies cost around $1 each.

I designed this to go with this little pair or baby pants, which I also made:

Next you need to put the sensatizer on the screen. I did this at night so it could dry/harden overnight.  Careful, you can't expose the sensatizer yet, so find someplace dark to work and store the screen while it dries.  Basically you add water to the tiny bottle of sensatizer and pour it into the large bottle of photo emulsion and shake it up. Pour a line of sensatizer across one of the sides of the screen and drag the squeegee across the screen.  Don't be stingy!  You can always scrape the extra sensatizer off the squeegee and put it back in the bottle. I kept dripping and squeegeeing and got these weird uneven spots.   Just keep squeegeeing both sides and it should smooth out nicely. (Before you start, put pushpins in the corners of the screen on the flat side so it doesn't touch the work surface (I didn't have any so I set the screen on the Speedball box at a 90-degree angle). The bottle of photo emulsion will keep in the fridge for a few months.

The next day the sensatizer was dry and I was ready to "burn" the screen. You want something large and flat to carry your assembled screen outside, and something dark under the screen - otherwise the light will bounce and expose the wrong parts (black poster board would serve both purposes, or you could use a big piece of cardboard with some black fabric over it). Then you put your screen face down (flat side up - remove those pushpins first) and your artwork face down (wrong side up) because when you turn the screen the right way your artwork is also reversed - see how the writing is backwards in the photo. Oh yeah, you should also tape the transparencies together so they don't blur your image.  Finally you need to put a piece of glass or plexiglass on the artwork to hold it in place. I used glass from a picture frame. Carry it outside and set it in the sun for a few minutes. Watch for the screen to darken to a grayish clay - this is very subtle. I wish I had a secret to make it easier to know when it's "done" but I don't.  Maybe as I get more experience.  I wish I had done more research about using natural sunlight because eHow. com said to expose it for 20 minutes which is waaaaaay too long. I waited 5 minutes because it was a very cold but sunny day but I think it was still too long. More on that later.

After exposing your screen, remove the glass and transparencies and your artwork should still be light green. Rinse the screen with cold water, using a sprayer to help wash away the light green parts. You have to spray the screen for several minutes and of course this is when my son decided to wake up from his nap. Screaming.  Also I wasn't really prepared for so much spraying - my kitchen floor was covered in water (sprayer hose too short, kitchen sink full - long story)!

Not a great photo but this is how it looks after it's burned, with the transparencies removed

Here's how it looks after you rinse the screen

The big moment - you're ready to print. Put something inside the shirt so ink doesn't leak through the layers, I used the same glass from the picture frame (first I used cardboard and the print was very faint so the harder surface helps).

Lay the screen flat side down on the shirt, put a blob of fabric paint above the image and drag the squeegee over it repeatedly. Practice on a piece of acts fabric first (or paper I suppose).  The thing no one tells you and that I haven't figured out yet is how to place the screen on your shirt just right because you can't see through the screen???

Then lift straight up on the screen and say a little prayer that it worked...

Hm. You can see that some of the fine lines in the image didn't print properly. I tried a second time, to see of the squeegee technique made a difference (holding it at different degrees) with the same result.  So basically some of the photo emulsion under the artwork didn't wash away, or it had been exposed, so the ink wasn't pushing through the screen in those areas. I had 2 more shirts to use so I decided not to be lazy and repeat the WHOLE process again to see if I got a better result. Sounds great BUT then I couldn't clean the exposed sensatizer off the screen.  There is a special remover and it just wasn't doing the trick, or I was doing it wrong, so I had to resort to other methods (scrubbing, baking powder...).  I was so worried that I had completely ruined the screen.

I still haven't given it a second attempt - I got busy with Christmas and ear infections and the like.  When I play with it some more and learn some tricks I'll report back.  But I do want to go over some other screen printing alternatives to consider.

The Silhouette Cameo - it's like a printer but instead of printing, it cuts.  Unlike the Cricut you don't need cartridges - you can download shapes for around $1 or design your own.  I got one for Christmas and have found there is a learning curve, just like with the photo emulsion process.  With the Silhouette you can cut "heat transfer paper" to make an iron-on design, or you can cut your design out of adhesives vinyl and then use it like a stencil with your silk screen - you can reverse the image and then stick it to the bottom of the screen, or you could put it directly on the shirt/item and use fabric paints and bypass the screen altogether.  Using the Silhouette to make stencils bypasses the photo emulsion process, it's more like fabric painting.

The Yudu - a whole screen printing system that looks like a little photo copier.  It does the whole photo emsulsion screen printing process with the following benefits:

• uses photo emsulsion sheets that stick to the screen instead of trying to get an even application of sesnatizer like I had trouble with
• has built in dryer to reduce that overnight or several hours of wait time
• has built in light so you don't have to wait for the perfect time of day to burn, or set up a screen printing overhead light (if you don't have the room for it, like me)

Hope this was helpful if you're trying to figure out how to go about printing your own graphics.