The Ultimate Quide to Screen Printing

June 17, 2021

Screen printing is an effective and efficient way of transferring images to fabric. In the past, screen printing was only possible to do at home with either stencil-cut images or photo stencils with the help of a UV exposure lamp. However, if (like most) you don't have a UV lamp, a stencil was a good way of creating simple images on fabric. 

However, detailed photo-quality results can't be achieved with a stencil, and transparent images required professional exposure. You can now buy a product that allows disclosure of photo-stencils onto a silkscreen using standard lamps. 

Firstly, some of you may wonder what screen-printing means. Well, it all centers on the use of a silkscreen. Silkscreen is a wooden or aluminum frame to which a mesh is stretched and attached. Nylon is commonly used for screen printing successfully onto fabric.

Screen printing works by adding a substance to the mesh surface that coats areas you DON'T want to print. The remaining regions allow pigment to filter through the mesh and transfer to your printing surface. 

A squeegee is used to pull pigment across the top surface of the screen. The pigment is transferred through the holes of the stencil onto the print surface. The paper areas of the stencil protect the fabric from the pigment in the areas you don't want to print to allow your image to be printed.

Photo-stencilling is a slightly longer process but allows more accurate results. Before we begin, I must stress that this is a guide and should not replace any manufacturer's guidelines or instructions. ALWAYS read these carefully as the guide I have written may not mention all manufacturer's recommendations. 

Please check these carefully and seek the manufacturer's support if needed. 

Equipment Needed

You will need:

  • Fabric to print onto. Woven fabrics such as cotton and wool (provided they are a tight, flat weave) work well. Cotton jersey also works well.
  • Pigment and binder 
  • A silkscreen. A4 or A3 size is good to start with. (Get one with a T size that is suitable to print onto fabric.)
  • A completely flat, smooth surface to print onto (a worktop)
  • A piece of rubber mat/ lino to print onto (optional)
  • A squeegee
  • Photo-emulsion starter kit
  • A spoon for mixing
  • Sponges and cloths
  • A lamp of 150W (or two lights with equivalent wattage)
  • A dark room or large cupboard with a flat ground surface
  • A piece of thick black card
  • Two strips of wood (equal dimensions)
  • OHP film/acetate/transparency film
  • OHP pen (optional)
  • A piece of glass that will fit into your screen frame (optional)
  • A spray gun/shower head attachment/wash trough/wash area that will fit your screen
  • Old soft paintbrush
  • Gum strip or masking tape.

Firstly. You need to prepare an image. Your image area to print needs to be BLACK the background nears to be WHITE (on paper) and CLEAR (when transferred to film). No grey areas or color at this stage. Make sure your lines are not too thin if they might not expose. 

If you are using a photo, then a program such as Adobe Photoshop will allow you to adjust to just black and white (Image – adjustments-threshold is a good way of doing this). 

Once you have your design in black and white (remember, the black area is what you will print), you need to transfer to clear acetate/transparency film.  

You can do this by either:

  1. Drawing directly onto OHP/transparency film with an OHP pen
  2. Printing from your printer onto OHP film
  3. You could ask a screen-printing company to transfer a black and white image to a unique film for this, but it will cost a little more.

Hold your image on film up to the light – if you can see the light through the black, it is not opaque enough and may result in over-exposure. Fill in any gaps with your OHP pen. A black and white image is needed on a white background. 

Prepare Your Screen

Next, prepare your screen. Photo-emulsion and sensitizer are mixed to form a solution that coats the screen and the screen remover. This will remove the solution once you have finished your image and start a new one. Again, make sure the kit you buy is suitable for daylight conditions, not UV lamps).

Read the instructions carefully on the leaflet provided. It will direct you to mix the sensitizer with water and add it to the emulsion. Mix well, and it will change color from blue to green. 

It is now sensitive to daylight and should be stored in dark conditions. Depending on the size of your screen, the mixture will probably allow for the coating of more than one screen.

Once you have mixed the sensitizer and emulsion, pour a thin line along the top edge of the top surface of your screen. Use the squeegee to pull the solution across the screen evenly. 

It is better to use a very thin layer.

Turn the screen over, use the squeegee to pull across the underside of the screen to even out the emulsion. You may need to add extra emulsion if you have gaps, or you may be able to spread out what is already there.

Dry Your Screen in Pitch-Black Conditions

The screen now needs to dry in pitch-black conditions. Place your screen topside up to dry on the strips of wood (the strips of wood will allow the screen to dry flat without touching the surface. The strips of wood must be of even size so that the screen is lying flat. 

Leave to dry overnight – make sure no light can get in. It is best not to leave the screen too long before exposing it. 

Expose Your Screen

You are now ready to expose your screen. First, you will need to set up your lamp(s) to the correct height. You MUST read the instructions carefully.

Place your transparency image on the surface of your coated screen. Don't place too close to the edge, as you will find it challenging to print.

To do this correctly, you should place a piece of clear glass over the film to hold it flush to the surface of your screen. The glass prevents blurred edges by keeping the image flush to the surface of the screen. But, again, check the manufacturer's instructions carefully.

Turn on your lamps and then leave it exposed for the time suggested in the instructions. It is vital to understand how the process works. Once the lamps are on, the light will harden the emulsion that is exposed to the light. The area protected under the black of your image will be protected from the light (providing you made sure the black was fully opaque). 

Once you have decided to remove the lamps, you will wash the screen in water. The areas protected by your image will wash away. The areas hardened by the light will stay put. So, if you take it out too soon, the surrounding areas will not have had a chance to harden sufficiently and might wash away with the image. On the other hand, if you leave it too long, no image is left to print with.

Turn off the lamps and remove the film image. You can reuse this another time if needed. Take the screen to a wash-trough or cleaning area and spray the screen with cold or lukewarm water. Don't use scourers for brushes as you can damage your image. A soft cloth/sponge rubbed gently while spraying can help. Spray both sides, repeating as necessary. 

It can take a while to wash out thoroughly, so be patient. Once you are happy that your image is visible, hold your screen to the light and make sure you can see the light fully through the image area.

If you can, you have exposed it successfully! If it hasn't worked properly, don't worry. Just clean your screen (see later in the post for details) and try again. Leave your screen to dry in an upright position.

Washing The Screen

To wash your screen:

  1. Scrape off any excess back into the tub.
  2. Spray with cold or lukewarm water on both sides to remove any pigment.
  3. Soak and peel off any gum strip.

You must clean both sides thoroughly and hold it up to the light regularly to check that you can still see the light through it. If you can't, it is blocked, and you may need to gently scrub with a soft brush and use some removal liquid. When clean, leave to dry upright. When dry, your screen will be ready to use again!

Once you have printed as many as you need, you can remove the image from your screen. Coat both sides of the screen with the removing liquid using a soft paintbrush. Let it stand for about a minute or so. Rinse off. Wipe with a soft sponge as rinsing if needed. Done!

Fixing Your Image (Preventing Wash Off)

To fix most pigments, you usually use heat—iron for about 4 min of a medium setting (depending on the fabric). However, check the manufacturer's instructions carefully. 

In theory, the pigment is unfixed until ironing (can be washed off); however, this isn't always the case, and once printed, it might be difficult to remove, fix, or no fix. To make it wash-proof, though, iron to settle permanently.

That's it! Once you have done it a couple of times, you will find your way of working that suits you.

Preparing The Fabric

You will next need to prepare your fabrics ready for printing. You will need to work quite quickly when printing (if the pigment dries in your screen, it can block it), so get the pieces ready for printing the first color. When you are prepared to print your first piece, make sure it is taped down. Work on a completely flat surface. 

A print mat (slightly spongy, fun foam is suitable) is ideal, but if your fabric is thick, you might be able to manage without it as long as your table is smooth and flat.

Tape the fabric to the print table. Ideally, tape around all edges or ensure it is secured at regular intervals. Be sure to use a print mat to ensure even printing and protect your worktop.

You can use different types of pigments for printing. To print lighter colors onto darker fabrics, you will need an opaque binder. It would be best only to have the tiniest drop of these pigments to mix your color. Make sure it is mixed thoroughly. 

If you are printing more than one color onto one piece of fabric, it is usually best to print lighter colors first. This is because you usually only print one color at a time before washing the screen and then repeating for the next color.

Add gum-strip to the edges of the underside of your screen. This will prevent leakage in any gaps between the emulsion edge and the frame. Also, if you have any pinholes or areas that you don't want to print, you can add pieces of gum strip to the underside of the screen to mask them out. You can also mask out whole areas of your screen. Use newsprint and masking tape/gum strip to mask these out.

Printing

Position the screen onto the fabric in the correct position. Using a teaspoon, spoon a small amount of pigment along one side just next to the print area. Spread this evenly. Place the screen in the correct position for printing over your fabric. Place a thin line of pigment at one edge.

Hold the screen down firmly with one hand and use the other hand and pull the pigment across the entire printable area. Then, turn the squeegee around and pull back across.

The amount of 'pulls' depends on the thickness/type of fabric/print surface. 

Generally speaking, the thicker the fabric, the more pulls you can do. Delicate fabrics may only require one pull. A dry pull is where you wipe off any ink from the squeegee and gently pull the squeegee over the printable area to remove any excess on the screen's surface. Make sure your screen does not move (not even slightly) throughout this process or it will blur.

Gently peel the screen from the surface from one edge. And presto, there is your print! Print as many as you need in this color. 

After each print, I usually BLOT the underside of the screen with a piece of cotton cloth or paper towel. DON'T RUB. The ink is drying the entire time, and if it dries in the mesh of your screen, it can block permanently. 

I often print only about three at a time before washing my screen. If you print too many at once, it will start to blur.