How To Print: Before the Ink Meets the Shirt

Ben Buzzard
June 22, 2023
water base oberon tshirt

If you want to know how to screen print your own apparel, this is a great place to start. But before we start the screen printing journey, it's essential to understand that getting a top-notch print involves many steps. These measures lay the foundation for success and ensure you obtain the best possible results. From obtaining high-quality artwork to mastering exposure techniques and utilizing sharp squeegees, there are key considerations to keep in mind.

To kickstart your screen printing endeavor on the right foot, here are some valuable screen printing tips to follow. By implementing these strategies, you'll enhance your chances of creating exceptional prints that leave a lasting impression. Remember, attention to detail and meticulous preparation are the keys to success in this craft.

High Quality Artwork

Whether you are creating the artwork yourself, or it is being supplied to you by your clients. It is important to make sure that the art file is a high resolution. Without good artwork it is impossible to make a good screen print. Here are three simple guidelines to help ensure that your clients get the best quality product.

1) Images must be vector or a minimum of 300dpi raster.

A vector file is created using mathematical formulas to build the designs rather than pixels, therefore they are infinitely scalable and will always have smooth curves.

Raster images are made up of a predefined grid of pixels, because of this there is no more data that can be gained if trying to enlarge the image. Raster images at a low resolution will also have a stair stepping effect around curves.

Bitmap VS SVG

2) Designs should be pre-sized to the print dimensions as expanding the image will cause a loss of quality.

If raster graphics are being used to design the print, it is best to make sure that the dimensions of the canvas are set to the final size of the print with the correct resolution. For example if a design is going to be 14x20 inches then you would want the canvas to be 4200 x 6000 pixels for it to print as scale using 300dpi.

3) Fonts need to be rasterized or converted to curves to make sure that font family is maintained.

When text is being used in a design that text will need to be converted to either curves if using vector art, or rasterized if using raster graphics. When a font is not converted to curves or raster, if the font family is not installed on a computer that opens it, a different font may be used in its place.

Correct Artwork Separations

Separating artwork correctly is just as important as having high quality artwork to work from. There are many ways of doing artwork separations depending on the final results you are looking for.

If you are looking for a vibrant plastisol print on a darker colored shirt, you are going to need to add an underbase to have the ink really pop off the shirt. If you are looking for a more vintage look, no underbase with plastisol ink is a great way to go.

If you are using an underbase for your separation, it is important to add what is called choking to the underbase layer. Choking is when you remove a couple of pixels from the edge of the underbase layer, to help prevent the under base layer from peeking out around the top color. If the top color is white, usually the underbase is not choked in that area.

If you are trying to create a simulated process screen print, you can try and make the separations yourself, but that is tedious and difficult. Most screen printing shops will use software to help in the process. Two of the most popular options are Separation Studio™ from Freehand, a standalone software that can separate from PSDs to PNGs, or UltraSeps, an action package for Adobe Photoshop that can also separate raster images.

Choosing the Right Mesh

There are a large number of different screen mesh options available. Your average shop will have 3 or 4 main mesh options and a few specialty meshes for the rare occasions you need an extremely low mesh.

Unless you are using specialty inks like a glitter, glow or puff the general consensus is to use a lower mesh screen for your underbase, and a higher mesh for your top colors.  This is because a lower mesh screen will be able to deposit a more even layer on the garment fabric, which will in turn allow for a smoother top print that also uses less ink.

If you are printing a simulated process job, or anything that has half tones in it, it’s recommended to use a mesh count that has a four times greater thread count than the LPI of the halftone used. If this four times or greater rule is not followed, you may end up with a moire pattern in the halftone area. Moire patterns can also be caused by having two screen printing on top of each other that are of the same mesh count. This is also another reason why you need to have a different mesh underbase screen than top colors.

As mentioned before, there are some inks that require lower, more specialty mesh counts to print them efficiently. You will know if this is the case by looking at the Technical Data Sheet of the ink, which can usually be found on the website of the supplier you’ve purchased the ink from.

Picking the Correct Ink Type

There are multiple different types of screen printing inks available. Depending on what types of garments you are printing on, or what the client is looking for will depend on the ink that you need to use. A couple examples are listed below.

If you are printing on garments that contain a high percentage of polyester you may need to use a low cure ink. This is because the average plastisol ink cures fully at over 320 fahrenheit. This temperature is past what is called polyester's sublimation point.

The sublimation point is the temperature at which the polyester fibers start to open up and can either give off or receive dye. If printed on a colored polyester garment, the dye from the garment will start to migrate or shift into the plastisol ink slowly. This will cause the ink to take on the color of the garment it is printed on over time. In order to avoid this a low cure ink should be used. A low cure ink will fully cure below the sublimation point of polyester, reducing the possibility of migration as long as the garment doesn’t get above 320 fahrenheit.

When printing on 100% cotton garments, the options available to you open up a lot. Cotton garments can accept nearly all ink types including water based, discharge, silicone, and plastisol inks. This is because unlike other material types, cotton with few exceptions doesn’t migrate ink, and the fibers can be bleached with discharge inks. The exception to this is when printing on garment dyed shirts that us the pigment dyed method. These garments can cause migration just like a polyester garment. In the example below you can see a white print on a blue pigment dyed shirt that caused the ink to migrate to pink.

White plastisol print on a blue pigment dyed garment, the white ink has migrated pink

Preparing Your Ink for Use

Depending on what type of ink you are using, there may be different requirements for getting the ink ready for press.

If you are using a discharge ink, the ink will need to be activated. Activating discharge ink means that you are preparing the ink for the chemical reaction that bleaches the dye out of the garment. To activate the ink a Discharge Agent powder (also also called an Activator) is added to the discharge base at a 6%-10% ratio by weight. This amount may vary depending on the manufacturer, check with the products Technical Data Sheet for the correct amount to add.

When using Plastisol ink sometimes the ink may become thick and hard to print. This may be because the ink is too cold. There are a few different things that can be done to help with thick ink.

The first method we would recommend is to use an ink mixer, or a paddle attachment for a drill to stir up the ink. This helps to reduce the viscosity of ink without thinning it out. If mixing up the ink doesn’t work, there are also additives that can be used such as a Curable Reducer, or a Softhand Additive, these products thin out the inks making them easier to print.

On the other end of that some times as well ink can become too runny. Usually runny ink is because it is too warm. The hotter ink gets the more it loosens up, it can get thin enough to the point where it is unusable. The only real way to thicken up plastisol ink is to cool it down. It’s best to keep ink at room temperature ~60-85 fahrenheit.

Picking Your Squeegees

When it comes time to push the ink through the mesh, the last thing you’ll need is a squeegee. There are quite a few options you can choose from when it comes to the squeegee. The most popular ones range between 65-90 durometer hardness, as well as triple durometer squeegees that are becoming increasingly more popular like the 75/90/75s.

Durometer refers to the hardness or stiffness of the rubber the squeegee is made from. The lower the durometer the softer and more flexible the squeegee will be.

65 durometer squeegees are popularly used on low mesh screens with special effect inks like glitters, glows, and metallics. This is because the lower durometer is able to push more ink through the screens.

75 durometer squeegees are the most common single durometer squeegee that you will find out there. It’s medium firmness and flexibility means that it lays down enough ink to cover nicely without being too thick.

90 durometer squeegees are the most firm squeegees that you will find in most shops. These squeegees are commonly used on high detail prints that have a lot of halftones. Laying down a thin layer of ink helps to maintain the detail and consistency of the print throughout the job.

75/90/75 triple durometers are the best of both worlds when it comes to laying down ink and keeping detail. The middle 90 durometer keeps the squeegee from flexing too much, while the 75 durometer outside is able to deposit enough ink to cover well.

Ben Buzzard
Updated:
June 22, 2023