Screen Printing 101- Part 2- Creating The Stencil

Part 1/ Part 2/ Part 3

Nothing gets printed without first being imagined and created by the artist- that’s you!

Creating Your Artwork  Print This Post

One colour printing is the foundation for silkscreen printing. Learning how to do this well will make learning multi-colour printing so much more simple. But first let’s talk a bit about what I mean by one colour printing and how it affects the artwork you design.

When you are deciding to print a design onto fabric or another substrate you will need to first decide how many colours you want to include in your design. This will impact the look of your design. Will it be one, two, four, or ten?

The difficulty and complexity of printing goes up exponentially with each colour you want you use. But your difficulty ‘tolerance’ should not be your only deciding factor in why you choose any number of colours over another. Sometimes the clever use of positive and negative in a one colour print can be surprising and charming. Sometimes you will need more than one colour to tell a story, or make your design elements “pop”. Sometimes your will want to balance cost of production with good design; your print might look great in four colours but it’s too expensive to make so you decide on two colours instead and modify your print accordingly. A couple of other considerations to make are:

• What you will put this design on; a t-shirt, a handbag or a greeting card? Make sure that the design you’re are creating is going to work for the medium it’s destined for.
• Finally, the size of your design is limited to the size of your screen. (minus 2 to 3 inches to allow room on the screen for the ink and squeegee.). With these factors in mind you can begin to create something for printing.

Remember that you don’t need to be a great artist to make a great screen print. You can use found objects, textures (like lace), type, clip art or pieces of iconic art (don’t steal other people’s artwork- that’s just not nice). Even shapes cut out of paper can create something unique.

Making a Stencil

Once you have your artwork it needs to be transformed into a stencil. Most screen printing is done with the direct stencil method, which more or less means the stencil is directly attached to the screen. This type of stencil is created when you coat your screen with photo-sensitive emulsion and use a film positive of your artwork to create a replica of your artwork on the screen. The film positive represents one colour layer of your image and is usually on a piece of transparency film. Therefore for each colour in your design a separate positive will need to be made. You can create the positive by computer or by hand.

Making a Positive by Computer

If you are designing your image on the computer then you should keep each colour you use on a separate layer. To print out a film positive turn on the layer you wish to print and select all elements on that layer,  adjust the hue saturation values so that what you have selected is completely opaque and black. Now print that layer onto transparency paper that is meant for your printer type. Make certain to use a high quality setting so that he black prints out opaque. Continue this way with all subsequent layers of colours, if you have any. It’s a great idea to print registration marks with each page. It will help you greatly when it comes time to matching up the colours when printing.

Making a Positive by Hand

You have a wide variety of options when you make your positive by hand. But the same rule remains; you need to produce a separate positive for each layer of colour in your print.

You can photocopy each colour layer onto transparency paper or draw each color onto transparency paper with an opaque black marker. It’s also possible to paint each colour layer with black acrylic ink, cut the image out of masking film, rub dry transfer lettering or even cut the image out of heavy card-stock or cardboard.

If you are making a multicolor print then it’s a good idea to use a registration mark- either drawn by you or one that you purchase on each transparency to match up each of the layers.

Regardless of what technique you use your film positive should be on translucent or transparent paper/ film (vellum, mylar, transparency paper) and the image should be opaque. When you hold your film positive up to the light, the light should pass through (or mostly) the clear areas of the positive and none should pass through the black areas.

When this image is used to expose your screen the black areas will absorb the light from your exposure unit and the clear areas will let the light pass through effectively hardening the photosensitive emulsion where it is clear.

Now It’s Time To Coat and Expose Your screen.

In the darkroom; or at least the dark area of your house you have set-up for coating your screens you will coat as many screens as needed for each colour layer in your print. Here are detailed instructions on how to properly coat your silkscreens.

Once your screens are dry you will adhere the film positive to your screen using clear tape before you take your screen into the lit areas of your house or studio. If your exposure light source comes from the top then you’ll place the film positive on the print side of the screen. If the light comes from the bottom, place the film positive on the substrate side of the screen and place it on backwards. Regardless of which side you place your film positive it should be centered and there should be 2-3 inches of space from the bottom of your image to the bottom inside edge of the screen. We call this area ‘the well’.

If your image is small enough to fit more than one film positive onto a single screen it’s OK to do that (a good rule of thumb is to leave two inches of space around each image). I prefer to put each color separation onto a different screen. Use the registration marks on your image to help center your image. Here are detailed instructions on how to register your colour layers using you registration marks. If you are making a one colour print your registration of your screen is less crucial. Generally, you mostly need to place your image onto the screen in the center and on straight.

Once your image is taped to your screen bring the screen out to your exposure table and place the screen so that the film positive is between the screen and the light source. You’ll use a piece of glass to weight down your positive so it sits flush with the screen.

Top down light source = black cloth<screen<film positive<glass<light source

Bottom up light source = light source<film positive<screen<glass

Expose your image according to the manufacturers instructions of based on your testing results.  More detailed information and a method for testing exposure times can be found in my blog post on exposing your silkscreens.

Washing out your screens.

Immediately after you have finished exposing your screens you should bring your screen to your wash out area. Remove the film positive from the screen. You will notice that there will be a slight change in the colour of the emulsion where it has hardened. With warm water rinse quickly each side of your screen and let it sit for 30 seconds. This will soften up the image areas that were not exposed. Next, use a sprayer attachment from your shower head, sink, garden hose or pressure washer to gently washout the image emulsion on the side that was facing the light source. Concentrate spraying the areas where the image is. If you use a pressure washer you must use it on the least powerful setting- less than 650psi otherwise you risk removing parts of the stencil that you shouldn’t. Continue to rinse on one side only until all the image has been removed. You can hold your screen up to the light to see if there is any emulsion remaining in the image area. It’s not necessary but some people wish to do this, you can turn your screen around and quickly wash the opposite side of the screen. Once all the emulsion is removed set your screen aside to dry completely.

*if you have small spots of emulsion that are hard to remove you can use the pad of your finger to rub them a bit while you are spraying. This friction is generally enough to help remove stubborn spots.

Once dry, you should check your screen for pin-holes. these are tiny 1 mm. holes the size of a pin head that will allow small specs of ink to pass through them when printing. You can check your screen by holding it over a light table or by holding it up to a window or light source. If there are any then you can take some emulsion and a small paint brush and paint in the hole. You can do this in fully lit conditions since you want the emulsion to harden. Let the pin hole spots dry once again and expose your screen for at least 1/4 of the full exposure time to harden the small spots.

Continue on to Screen Printing 101- part 3 and find out how to print properly to get the best results.

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