Wednesday, 3 April 2013

Screen printing fun

I've had friends enquire about the screen-printing process, so while I am by no means the most expert person around to do so, I thought I'd do a little blog on the subject. :) To many people reading this it will probably all be well-known and obvious, but not to everyone, so why not?

Screen-printing bonanza! The first thing you need to do is design your print and separate it into a series of layers. Each layer corresponds to a different layer of ink, usually one different colour for each layer (including lineart). If a print has more than one colour, it's basically three different images printed on top of one another. 

Depending on what sort of print you're doing, it can a good idea to take a reference, e.g. one coloured in Photoshop - gives you an image to work to and helps you get your colours right. Below is a pic of my photoshop mock-up, before I slathered a load of paint on it to check the colours...

In order to get all the layers onto the screen, you first print or photocopy them onto acetate, all in black (ideally as true-black as possible).

You then get your screen, go into the darkroom and coat it in green, photosensitive goo. Below is a picture of my screen before it's had the emulsion applied.

When the darkroom light is on, don't leave the door open! The whole basis of the photoemulsion is that you use light to define your image, so letting light in could mean the emulsion doesn't set properly. :)

The time while you're waiting for the emulsion to dry is a good opportunity to mix up any colours of ink that you need. :) For this you use either specific screen-printing colours, or you can use decent-quality acrylic paints and mix them with a special gloopy screen-printing medium.

 When the emulsion has dried, you take your images on acetate and your screen and use the UV box (the giant machine thing in the pic below) to "burn" the image onto the mesh; that is, the light passes through the black areas and removes the emulsion accordingly; the area of mesh where your photoemulsion has been removed is your stencil.

 You then take the hose and give your screen a bath, washing off the burned-off emulsion until your stencil appears! :) That hose on the right is a pressure washer, and is like a hardcore water gun. You don't need it all the time but when there is cause for using it you feel like Arnold Schwarzenegger (or the Simpsons parody of him at least). Take that, last traces of stubborn emulsion that won't come off!

This is where the pictures become less informative since I actually had to get to work printing. :) Once your screen has dried (there's a lot of waiting for screens to dry) you grab a squeegee (pictured below!), tape up bits of your screen that need taping up and fix it into the screen bed. The bed/table has a vacuum function that holds the paper underneath in place.

You then smear on some ink, pull it across the screen using the squeegee and back again, making sure enough ink is distributed on the screen (i.e. that it's "flooded"). This ensures even coverage and helps stop it drying out.

These pics are actually of my second/middle layer, that is the darker purple swirls. This is what my prints looked like after the first layer - the ones on wonky paper are test prints:

It's important to "register" your print to make sure the ink goes down where you want it. This is important for the first layer too, but it's especially important when you're doing an image with multiple layers; if you mess up, your lineart could be halfway across the page from your shading! So, first you print onto a largeish sheet of acetate taped to the screen bed. This means you can check exactly where your ink's going to go and position your sheet of paper accordingly.

When you've done a second layer out of three, chances are you'll have something like this! You then leave the prints to dry on a drying rack and go and thoroughly wash the ink off your screen.

If your third layer isn't already burned onto your screen, and you don't have it on another screen sitting ready to go, you'll need to remove all the emulsion from your screen using a chemical spray stuff (and, sometimes, the pressure washer), re-coat it with emulsion and burn your last stencil onto it. More waiting-to-dry/mixing colours/lunch/making tea time...!

Then you go through the whole printing process again with the final layer, hopefully not messing up too much, and you get your finished result. Voila! :)

 While it may seem a long and convoluted process to print by hand, what can never come across fully in my amateur photos reproduced online is the visible difference in quality between my initial mock-up image and the finished print. My home printer is pretty good, but without some serious industrial/giclee technology it's incredibly hard to get something that looks as vivid and strong as a hand-pulled print. :) It's a quite physical and time-consuming process but it's enjoyable and very much worth it, and with every hand-pulled print you get something that is real and unique. :)

Hope this wee blogging session has been informative for at least a few readers..! Expect another post with my finished print soon....

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