Beginners Guide To Screen Printing
Silkscreen printing is a process of printing various designs onto different kinds of substrates using a silkscreen mesh. The process includes design preparation, screen preparation, and the actual printing of the design onto the substrate. Although there are only three major parts on this process, it’s actually easier said than done, especially for those who have zero knowledge about it.
That being said, we decided to create this post to help those who are just starting up. If you’re already an expert, you probably know what is written here, but if you have something to share, don’t hesitate to leave a comment below. :)
Also, this post is accompanied by a video on another post. For this process to be clearer to you, make sure that you watch the video as you read this post.
Basic Screen Printing Materials
Before you start the process, the first thing you must to do is to prepare all the things you’ll be needing. We’ve mentioned this in our previous post, but let us list them down here again. :)
- Screen Mesh (120 mesh will do)
- Squeegee (70 durometer for general use)
- Screen Frame (wooden or aluminum)
- Aluminum Adhesive (for aluminum frames) or Gun Tacker (for wooden frames)
- Photo Emulsion
- Emulsion Scoop Coater
- Exposure Unit
- Heat Gun or Blower
- Wash-out Area
- Platen / Pallet
- Computer (this one is obvious. lol!)
- Acetate / Transparent Films
Step 1: Color Separation
Your design is the first thing you need in this process. Besides the fact that you need a design to print onto the substrate, you also need a design so that you can properly price a printing project.
In silkscreen printing, the number of colors of a particular design is the biggest factor in pricing a project. If a particular design has more colors, the higher the price can get, and let me explain why.
The reason why a 3-color design will incur a higher price than a one or two-color design is because in silkscreen printing, each color is printed separately using different screens, which means more preparation work is needed.
Part of the design preparation is a process called “color separation”. This is the process where you separate each color so you can transfer them separately onto their respective screens.
Assuming you already know how to use photo editing software like Adobe Photoshop, Adobe Illustrator, and CorelDRAW, you’ll find this step pretty easy to do. For beginners, let’s assume that you’ll be printing a one-color design.
Note: If you have a low quality image, it is imperative to make the quality as high as possible because what you’ll print on your paper or films will be the same as what you’ll print onto the substrates. You can make the image quality higher by retracing or redoing the whole design.
Step 2: Printing The Design To Make Your Stencil
Once the design is prepared, the next step is to print it out on your transparency film / acetate. This printout will be used to transfer the design to the screen, which will then be used to print the design onto the substrate.
Note: If you’re using transparency films, make sure it is compatible with your printer. If your printer is an inkjet printer, use a inkjet-compatible film. If your printer is an laser-printer, use a laser-printer compatible film.
Besides films, you can also use plain bond paper to print your design. But, if you choose to use bond papers, you’ll need to use cooking oil to successfully transfer your design to the screen later on.
Screen preparation is an important step that some printers don’t bother to do correctly. Based from experience, poor screen preparation is one of the most common causes of failures in making a good stencil for your design. Ignoring simple steps can cause you more time and money because you’ll probably do the whole process all over again if you fail to produce a good stencil.
Step 3: Making Screens
For seasoned printers, this step is done prior to preparation of the designs because most of them stock their screens so that when there’s a new project, they already have ready-to-use screens. But for starters, let’s assume you don’t have any screens available.
Once you have a screen frame and mesh available, you need to put the screen mesh on the frame. You can do this by stretching the screen mesh using a “screen stretcher”, and attaching it on the frame using either a gun tacker (for wooden frames), or adhesive (for aluminum or steel frames).
Note: Some people stretch their screens by hand. This process is very vulnerable to errors especially in getting the correct tension on the screens. Getting the correct tension is very critical in screen printing because a screen that is not stretched enough will give you a hard time creating a good stencil.
Step 4: Degreasing The Screen
This step simply means cleaning the screen and freeing it from any dust or dirt before coating it with emulsion. This step can prevent your screen from having pinholes later on when you’re done exposing it.
The chemical used in this step is called a “screen degreaser”, which is available on some printing supplies stores. Simply use the degreaser and a brush to thoroughly scrub the screen on both sides.
Tip: If you can’t find any screen degreaser, you can simply use a dish washing soap and a brush.
After cleaning the screen, dry it in a place where it won’t be contaminated by dusts or dirt.
Step 5: Coating The Screen With Emulsion
Once the screen is totally dry, the next step is to coat the screen with photo emulsion. Photo emulsion is a chemical that, when mixed with sensitizers, becomes extremely sensitive to light. It is used to transfer your design to the screen by sticking your film onto the emulsion-coated screen and burning them using your exposure unit. Because your design is printed on the film in black ink, it will block any light from the exposure unit, leaving an unexposed area of the emulsion similar to your design.
Tip: There are different kinds and brands of emulsion. There are emulsions that can only be used for water-based and plastisol inks, and there are those who can only be used for solvent inks. Make sure to use the correct kind of emulsion for your project.
Coat the screen with emulsion using a scoop coater. You can use other coating tools, but based from experience, using a scoop coater will give you a much even coat on the screen. Coat the screen one on each side (or two if thicker stencil is required), and dry it using a blower or heat gun with the substrate side facing down.
Note: When you’re drying the emulsion, make sure that you’re doing it on a dark room or some place where there is minimal lighting. Remember that the emulsion is very sensitive to light, especially when it starts to dry. Drying it in a well-lit place will burn and harden the emulsion, making it impossible for you to transfer your design onto the screen.
Step 6: Expose The Screen
After drying the emulsion on the screen, you’re ready to transfer your design onto it. The most convenient way to do this is to use the transparency film where you printed your design.
What you need to do is to place your design on the substrate side of the screen. The position of your design depends on what kind of press you’re using, so make sure to measure everything to know its exact position. If you’re not using a vacuum exposure unit, you need to put some weights on your screen to make sure that the screen and film lay flat against the glass.
Once you’re set up, set your timer and turn the exposure unit on. Remember to keep the lights in the room off while doing this process.
Note: The exposure time depends on many factors, such as distance of the screen from the light of the exposure unit, how many lights you’re using, the brand or kind of emulsion, and if you’re using a paper or transparency film for your design.
Because of these factors, it is hard to tell the exact exposure time you should use. The best way to know the correct time is to do a step wedge test (which we will share in this page soon).
Step 7: Wash Out The Screen
After exposing the screen, it’s time to wash it out. Washing out the screen simply means that you make your design pop-out on the screen by using water to remove the unexposed part of the emulsion (which is your design).
Using a power wash is the easiest way to wash out your screen, but if you don’t have one, a simple hose will do.
Note: You can only use a power wash if you’re using a water-resistant photo emulsion. If you’re not, you should only let the water flow on the screen until the unexposed part of the emulsion slowly washes out. Using a power wash on a emulsion that is not water-resistant will easily destroy your stencil.
Step 8: Applying Emulsion Hardener (for non water-resistant emulsion only)
For those who aren’t using a water-resistant emulsion, applying an emulsion hardener on your exposed screen is a MUST. Since your emulsion can’t withstand water and pressure, it will easily wear out when you use water-based inks on your prints. So, to make your stencil harder and stronger, simply apply an emulsion hardener.
Note: once you use a hardener, you can’t reclaim the screen anymore. This means that once you’re done with the design, you need to remove the screen from the frame and replace it with a new one.
This is the number one reason why we prefer to use water-resistant emulsions. Water-resistant emulsions don’t need hardeners to withstand water and pressure, allowing you to reclaim the screen and reuse it again for a different design.
Based from experience, reclaiming screens is one of the best ways to keep your materials expenses low because screen mesh is one of the most expensive materials in silkscreen printing.
Simply apply the hardener using a piece of cloth on both sides of the screen and let it dry.
Step 9: Printing On The Substrate
Now that your screen is ready, the next and final step is to print your design onto your substrate. This step is the most simple, but requires the most practice. Many beginners (including me when I was a newbie), are having various problems in actual printing like screen clogging, difficulty in flooding, or smudge print is normal.
Don’t be frustrated if you experience them because as I’ve said, getting used to this process takes time and lots of practice.
Flood and Stroke
The ideal way of printing on substrates is by flooding before stroking. Before you actually stroke the paint using a squeegee, you must first flood the screen with paint. The main reasons for these are:
- To ensure that when you stroke the paint, the whole design will be printed on the shirt.
- To prevent the paint from clogging the screen quickly.
This technique is very important, so it’s highly recommended that you use a silkscreen press machine that can register your screen on the press itself. Without registering your screen on the press, you can’t actually preform this technique because you’ll probably be doing it manually (meaning you’ll register your design on the shirt by instinct and eyes, especially if you’re doing multi-color prints).
Tip: Whenever you print on a garment and it will take you a longer time to print the next one, make sure to wipe your screen (on the substrate side) with a wet sponge to remove the inks on your stencil. Your screen will be clogged with ink if you don’t, and it can get to the point where you’ll have a very hard time removing it.
So, that is the simple process of silkscreen printing. Don’t be overwhelmed with the steps I mentioned here. Once you get used to the process, you’ll be able to do these steps more efficiently and faster.
Just remember that it will take time and practice to develop your skills in screen printing, so keep on trying different things and find out what will work best for you.
Thank you so much for reading. If you have any questions, thoughts, or you find this post useful, let us know by leaving a comment below.
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Alwin (Instagram: @alwin_rys)