Silk Screen Printing: Crafting Custom T-Shirts

Screen printing is a great way to transfer a printed design onto a T-shirt. The process involves a chemical technique called photo emulsion. While that may sound complicated, it's actually quite simple. To get started, you'll need to select a design and prepare your silkscreen frame. This involves coating the frame with emulsion and exposing it to light, which hardens the emulsion. You'll then need to wash out the unexposed emulsion, leaving a stencil of your design on the screen. Finally, you can use the screen to print your design onto a T-shirt.

Create a design

Creating a design for silk screen printing is a fun and rewarding process. Here is a step-by-step guide to help you get started:

Select a Design:

Start by choosing a design that is simple and easy to work with, especially if this is your first time silk screen printing. Consider using a silhouette or a basic image with one colour. You can also add text to your design, but remember to keep it straightforward.

Prepare Your Image:

Once you have selected your design, you will need to get it ready for printing. If you are drawing your image by hand, use a thick black marker to outline it and then scan it to your computer. If you are using an online image, make sure it is in black and white. You can use programmes like Photoshop, Microsoft Word, or PowerPoint to edit and convert your image.

Print Your Design:

Print your final black-and-white design onto a clear transparency sheet. Remove any regular paper from your printer and replace it with the transparency sheet. Double-check that your image settings are correct, and then print. You may need to adjust your printer settings to accommodate the transparency sheet.

Set Up Your Workstation:

Cover a large, flat work surface with newspaper to protect it from chemicals. If you don't have enough newspaper, you can use an old sheet or tarp. Set up your workstation in a dim room, and avoid direct sunlight as the UV light can affect the emulsion chemical you will be working with.

Mix Your Emulsion:

Wear rubber gloves for protection and use a disposable utensil to mix your emulsion and sensitizer according to the manufacturer's instructions. These chemicals are photosensitive and will harden when exposed to UV light, creating a stencil for your T-shirt design.

Prepare Your Silkscreen:

Place your silkscreen frame (a wooden frame covered with thin mesh) on your workstation. Elevate the frame by pushing a pin into each corner, and then place your mixed emulsion into the well of the frame. Use a squeegee to spread the emulsion over the screen, creating a thin coating. Don't worry if you need to add more emulsion; just be careful not to use too much to avoid dripping.

Dry Your Silkscreen:

Flip the frame over and coat the flat side with emulsion. Make sure the coating is smooth to avoid imperfections in your final print. Rest the screen on the push pins and leave it to dry overnight in a dim space. You can speed up the drying process by placing a fan near the screen.

Now you are ready to expose your design onto the silkscreen and prepare for printing!

Prepare the screen

The screen is the most important part of the silk screen printing process. It is a wooden frame covered with thin mesh that will act as a stencil for your T-shirt design. You can buy a pre-made screen or make your own.

If you're making your own, cut a piece of 110 mesh fabric, leaving enough overhang to wrap around the frame. Staple the fabric to the frame using a staple gun, pulling it taut as you go to ensure the screen is tight. Trim off any excess fabric, being careful not to cut or damage the screen surface.

Next, you need to coat the mesh with emulsion to expose the design onto the screen. Before you do this, clean the mesh with a special screen printing degreaser to ensure any dust, lint, or particles are removed.

Mix the emulsion and sensitizer according to the manufacturer's instructions. This mixture will harden when exposed to UV light. Using a squeegee, spread the emulsion over both sides of the screen, creating a thin coating. Place the screen on push pins so that it is elevated and leave it to set in a dim space overnight.

Once the emulsion is dry, you can expose it to light to harden it further. Place a transparency sheet of your design and a glass sheet onto the flat side of the frame. Position a light source with a 250-watt lightbulb above the frame. Expose the emulsion to the light according to the manufacturer's instructions—this could take anywhere from one minute to one hour.

Finally, wash off the excess emulsion with cold water. You can use a garden hose or showerhead to spray the screen until a stencil of your design is visible. Leave the screen to air dry for around 30 minutes.

Expose the emulsion to light

Now that you've prepared your screen and image, it's time to expose the emulsion to light. This is a crucial step in the screen-printing process, as it will determine the quality of your final print. Here's a detailed guide on how to expose the emulsion to light:

Prepare Your Work Area:

Before you begin, make sure you're working in a dimly lit room or a darkroom. UV light can affect the exposure process, so try to minimise any UV light entering the room. Cover any windows or openings that let in sunlight. If you can't control the lighting in your work area, consider using a thick, dark fabric to cover the screen while it's exposed to light.

Gather Your Materials:

You'll need a few things for this step:

• Your prepared screen with the emulsion (make sure it's completely dry)
• A transparency sheet with your design
• A sheet of glass or acrylic (larger than your design)
• A light source (a 150-watt light bulb or similar is recommended)
• A timer or stopwatch
• A shower/hose with a spray nozzle or a jet washer
• A towel or cloth for drying

Position Your Transparency and Glass:

Place your transparency sheet on the flat side of the screen, making sure it's aligned correctly with your design. The printed side of the transparency should be facing the screen. Use a small piece of clear tape to secure the transparency in place. Then, place the sheet of glass or acrylic over the transparency. This helps keep the transparency flat against the screen and prevents light from leaking underneath.

Position your light source above the screen, approximately 12-18 inches (30-46 cm) away from the surface of the screen. Make sure the light is in the "off" position at this point. If you're using a lower-power light source, you may need to adjust the distance or exposure time accordingly. Ordinary light bulbs are not suitable, as they don't have the correct light spectrum and are not powerful enough. LED lights can be used, but they must be equivalent to a 1000W halogen bulb (about 45,000 Lumens). Once you have your light source in place, turn it on and start your timer. The exposure time will depend on the type of emulsion you're using and the intensity of your light source. Refer to the instructions that came with your emulsion for the recommended exposure time.

Wash Out the Screen:

After the allotted exposure time has passed, turn off the light and remove the glass and transparency sheet. Take your screen to a washout area. Give the screen a light spray with cold water on both sides to wet it, and let it sit for about 30 seconds. This helps soften the emulsion. Then, start washing out the screen from the print side (the side with the transparency). Focus on the finer details and small lines first, gradually moving to bigger areas. Once all areas have been washed out from the print side, give it a quick rinse from the ink side, being careful as the emulsion is thinner on this side.

Dry the Screen:

After washing out the screen, use a towel or soft cloth to wipe it down gently. Let the screen dry completely before moving on to the next step. Drying can take anywhere from 1-3 hours, depending on how thin your emulsion coating is. You can speed up the drying process by using a fan set to low, pointed at the screen. Make sure the screen is fully dry before printing, as damp emulsion can be easily damaged.

Set up the silkscreen

Setting up the silkscreen is a crucial step in the screen printing process. Here's a detailed guide on how to set up the silkscreen for T-shirt printing:

Workstation Setup:

• Choose a dimly lit room for your workstation to prevent UV light from hardening the emulsion prematurely.
• Cover your work surface with newspaper or an old sheet/tarp to protect it from chemicals.

Silkscreen Preparation:

• Elevate the silkscreen by pushing a pushpin into each corner of the flat side of the frame. This will allow you to work on the well of the frame.
• Mix emulsion and sensitizer according to the manufacturer's instructions. Wear rubber gloves during this process.
• Place 1-2 tablespoons of the emulsion mixture into the well of the frame.
• Use a squeegee to spread the emulsion evenly across the screen, applying gentle pressure. Rotate the frame as needed to cover all areas.
• Flip the frame over and coat the flat side with emulsion, being careful not to touch the sides with emulsion.
• Use the squeegee to smooth out any drip marks and ensure a smooth, even coating.
• Let the screen rest on the push pins and leave it to set overnight in a dim space. You can speed up drying with a fan.

Exposing the Emulsion:

• Place the transparency sheet (with your design) and a glass sheet onto the flat side of the frame. Ensure the room is still dim.
• Position a light source with a 250-watt bulb above the frame. The light should be about 18 inches above the screen.
• Expose the emulsion to light according to the manufacturer's instructions. This will harden the emulsion.
• Spray the screen with cold water to remove the wet emulsion.
• Allow the screen to air dry for about 30 minutes.

Now your silkscreen is ready to be used for printing! Remember to always handle emulsion with care and wear protective gear like rubber gloves.

Transfer the design

Now that you have your silkscreen frame with the design stencil ready, it's time to transfer the design onto your T-shirt. Here are the steps to do that:

• Slip a piece of cardboard into your shirt to keep the fabric layers from touching and prevent ink from staining the back of the shirt.
• Position the flat side of the screen (the side with the stencil) against the front of your T-shirt. Place the image in the upper centre portion of the shirt for a traditional look, or off-centre for a less conventional design. Ensure that the fabric underneath the screen is smooth and not bunched up to prevent ink from leaking out of the stencil.
• Put 1 tablespoon (15 mL) of screen printing ink above your design, arranging it in a line that is the same width as your design.
• Use a clean squeegee to pull the ink across your design. Pull the ink in a single direction to ensure a smooth, thin layer. Continue to pull the ink over the design until it is evenly dispersed. For larger designs, add more ink if needed, but be careful not to oversaturate the fabric.
• Remove the screen from the T-shirt by lifting it straight up. Be careful not to jostle the fabric.
• Allow the ink to air-dry for 30-60 minutes. Refer to the manufacturing instructions on your particular screen printing ink for specific drying times.
• Set the dried ink with heat to permanently press the design onto the T-shirt. Ironing is a common method, but some brands may require exposure to sunlight or setting in a dryer.

With these steps, you can successfully transfer your design onto a T-shirt using the silk screen printing method.

Frequently asked questions