Print your own t-shirts, posters and more.
Screen printing, Silk screening or serigraphy is a printmaking technique that creates a sharp edged image using a stencil. It is commonly used to print t-shirts, hats, tote bags, cd/dvd’s, posters, bumper stickers and a lot more. There are many materials and shapes that can be screen printed including ceramics, wood, plastics, glass, metals and paper.
The materials used in screen printing are very affordable and most of the equipment used can be built at home for very low cost.
The minimum items needed to screen print are:
• Scoop Coater
• Exposure light source
• Light sensitive emulsion
Screen printing screens are wood or metal frames that are covered with a stretched fabric mesh attached to the frame. The mesh has holes in it that allow ink to flow through the screen. Mesh is rated in how many and what size the holes are. This will determine how much ink passes through the screen and onto the substrate or the material being printed.
Screens can be made or bought with the mesh pre-stretched and attached. Purchasing the pre-stretched screens are the best way to start.
Squeegees are used to push the ink through the screen and onto the substrate. The squeegee also sheers or cuts the ink so you end up with a sharp image. They come in many different sizes and durometers. Durometer is the unit of measure for the hardness of the rubber portion of the squeegee. They also come in square or rounded with metal or wood handles.
In my opinion, the best squeegee to start with would be a 70 durometer square blade. That will give good flexibility and the square edge will shear the ink.
Exposure light source
An exposure light source is any light that gives off ultra violet light (UV). Most light sources give off UV but some give off more than others. The more UV the light source gives off the faster you will expose the screen. Examples of light sources you can use are:
– The sun
– Unfiltered Black Lights
– Halogen Work Lights
– Mercury Vapor
– Metal Halide
The sun is the most inexpensive source but is hard to control exposure times. Many people start out with an $8 halogen work light from the local home improvement store.
Light Sensitive Emulsion
Emulsion is applied to the screen mesh and blocks all the holes except where the image is. The emulsion is sensitive to UV light and will harden or cure in the areas exposed by the UV. The art is printed on a clear or frosted sheet of plastic and then placed on a screen coated with emulsion. The light is blocked in the area of the art and remains uncured. The uncured emulsion can be washed out and the remaining cured emulsion will block the ink.
Ink comes in many different types depending on the material being printed on. The most common for t-shirt printing is Plastisol. Plastisol isn’t ink at all. It is a liquid plastic that will harden or cure when exposed to heat of at least 320 degrees. Once the plastisol is cure the shirt can be worn. The other type of ink is water based that needs time to air dry. Water based inks will dry in the screen if you don’t keep the screen flooded where plastisol will never cure until exposed to heat. For frequent prints, some printers will leave plastisol in screens for months.
The scoop coater is used to apply the liquid emulsion to the screens
Part 2 coming soon