Buying Guide - Screen Printing Basics

Basic Materials
The products you purchase for your screen printing studio will depend on your original image, the type of stencil you use and the material you'll screen print on. There are a few essentials required for all screen printing processes, while specific materials are required for each different method. Whether you're a beginner in need of a refresher course or an old hand wanting to advance your skills, an informative book or video can be a very wise purchase. Please see some of our current resources on Screen Printing which can be found in the visual resources index at the end of our annual main catalog.

Very basically, screen printing involves transferring an image to a screen printing fabric, producing a stencil. Ink is passed over the stencil and deposited onto paper, fabric, etc. The screen can be cleaned and reused if desired.

• Frame Unit (including hinges and base)
• Screen Printing Fabric
• Squeegee
• Masking Tape
• Staples or Cord
• Scrub Brush
• Screen Ink
• Spoon
• Stencil Material
• Bleach or Mesh Detergent
• Screen Filler Rags
• Brush
• Scissors
• Newspaper
• Printing Paper

The Frame
The screen frame unit consists of a wooden frame (grooved on one side if ready-made). The frame should be sealed to avoid warping. Hinges are attached to the frame and the base to aid in registration and ease of printing. Screen fabric is tightly stretched over the frame using staples or a cord-in-groove method. Tape is applied to the fabric where it meets the screen, keeping ink from seeping under the frame.

Types of Fabric
Which screen fabric should you choose? Multifilament fabric is durable, economical, holds ink well and is ideal for stencil films. Monofilament is smoother, durable and offers exceptional detail. Organdy is low priced and better for short runs. A high mesh count (16xx) is used when high resolution is desired and the material being printed on is smooth or less porous. For printing on paper, either 14xx or 12xx meshes are suitable. When printing on fabric a good amount of ink needs to pass through the screen. A 10xx mesh fabric will work well. Silk comes about 40" wide and is sold by the yard.

Stencil Methods
A variety of stencil methods may be used to transfer the original image onto the screen fabric. Here is a brief overview.

• Paper Stencil
  A shape is cut from paper and placed on the outside of the screen. The ink will be deposited everywhere except where the paper is blocking the screen. The paper will stick for a very limited number of runs.
• Film
  Screen printing film consists of two layers. One layer is gently cut using an artist's knife. The areas where ink is to pass through are peeled away. The film is adhered to the screen fabric using water or adherent depending on the type of film used. The backing layer is then removed. Screen printing films are excellent for original images. Edges of color areas are crisp and well defined.
• Block Out
  A drawing fluid or touche is used to draw an image in the screen fabric and allowed to dry. The entire screen is then covered with screen filler. When the filler has dried, the drawing fluid or touche is rinsed out with cool water leaving the finished stencil. If the screen will be reused, wash the filler out with hot water and a scrub brush.
• Photo Stencil
  A light-sensitive solution or light-sensitive photo film is applied to the screen fabric. The original image on a transparent or translucent paper is place between the film and a light source and exposed. The screen is then rinsed leaving the image. This method offers the highest degree of resolution and gives long printing runs.
• After you have chosen a stencil method you must choose a screen printing ink that is compatible to your stencil material. The ink must also be compatible with the surface you are screen printing. When teaching, you may also want to consider the age level you are working with. As a rule, water based products are generally safer to use with younger students. Water based products are also easier to clean up without the use of solvents.
• There are a number of modifiers that will change the consistency of the ink. If your ink is drying too fast, a retarder may be added. Use retarders sparingly. Thinners will improve the flow of an ink that has gotten too thick. It may also improve the adhesion of the ink to the working surface. An extender base will improve the working qualities of the ink and stretch your ink up to 25% without affecting the color intensity of your ink. If used in greater amounts, an extender will give your ink transparency.

Squeegees
You will need a squeegee to draw the ink over the screen and push the ink into the printing surface. The length of the squeegee should be 2 inches longer than the print image and 1 inch smaller than the length of the frame. The blade is usually made of a rubber-like material. The edge is normally a V-shape. This is ideal for printing on paper. When printing on fabric the blade should be rounded. This will allow more ink to pass through the screen.

Printing: The Process
To begin printing, attach your prepared screen frame to the base using hinges. Place your paper or fabric on the printing base under your stencil image. You may choose to place registration guides on the base to position future prints or to make multi-color prints. Mix the ink to a creamy smooth consistency. Have your squeegee at hand along with a rag or paper toweling for quick clean ups.

Apply the ink to the edge of your screen closest to the hinges. Start with enough ink for a number of prints. Keep the frame up off of the material you are printing. Your first pass of ink will be the flood stroke. This stroke fills the screen with ink and keeps the ink from clogging in the screen. You will make a flood stroke before each print. Hold the squeegee on an angle so the blade is resting flat against the screen.

Your next stroke will be the printing stroke. When printing paper, an off-contact position of the screen is desired. This involves the position of the screen to be slightly lifted from the paper. The printing stroke will push the screen down onto the paper. After the stroke, the screen will snap back off of the paper. When printing on fabric. You will want an on-contact screen position. In this case the screen will remain on the fabric throughout the printing stroke. In either case, hold the squeegee at the same angle as the flood stroke. Use enough pressure to keep the ink in front of the squeegee. Lift the frame and examine your print.

At this time you may need to make a few corrections if your print is not sharp and clean. Occasionally you may need to fill in any pin holes around your image where the stencil was not solid. Clean the ink from the screen and use screen filler to repair any holes. Your image may be blurry due to too thin a consistency of ink. Blurred images may also be the result of a dull squeegee, an on-contact printing position for paper or too many flood strokes per print. If parts of your image are not showing, the ink may be too thick to pass through the screen or the ink may be drying too quickly and clogging up the screen. Remove any clogged ink and add retarder or thinner to your ink. If the ink was deposited unevenly, you may have forgotten the flood stroke before each print or your squeegee may have gotten nicked or become dull. You can sharpen a squeegee with fine sandpaper.

Clean-Up
After you have finished your printing session, you must clean your screen before the ink dries in the screen. This will enable you to use the screen for more prints at another time. Using a piece of cardboard, scoop up the excess ink and put it back into the can. Place a piece of newspaper under the screen and pass the squeegee over a few times. Repeat until most of the ink is removed. If using an oil based ink, apply the recommended solvent to the screen and pass it over the screen onto newspaper. If using a water based ink you may remove the screen from the hinges and spray water through it. Use water at a temperature that will not remove the stencil filler. See stencil product's instructions for the correct water temperature. Failure to remove ink from the screen will affect future printing runs.

To reclaim your screen for new images, you must remove the stencil material. See the removal instructions for the stencil product used. Generally, water soluble stencils are removed with hot water, a scrub brush and elbow grease. Solvent based stencils are removed with the recommended solvent such as mineral spirits. There may be a stencil remover designed specifically for certain stencil materials. Finish cleaning your screen with a detergent. Be sure to keep your screen free of any grease or oils. The faster you reclaim your screen after the previous printing session the easier your job will be. You may replace the screen fabric in the frame when a screen cannot be successfully reclaimed.

We hope your experiences with screen printing are creative and enjoyable. Consulting books or videos on screen printing techniques will give you better insight and provide inspirational ideas. Please see some of our current resources on Screen Printing which can be found in the visual resources index at the end of the Sax Main catalog. Good luck!