UNIT TWO: SCREEN PRINTING

This unit explains the process of screen printing

Learning outcomes

By the end of the lesson, learners will be able to:

  • Attach screen fabric to a wooden frame
  • Understand what a Light Box is
  • Discuss what Screen Fabrics are
  • Identify the three methods for Screen preparation

ATTACHING SCREEN FABRIC TO A WOODEN FRAME

  • Mark the four corners of the frame “A, B, C, and D”.
  • Take “A-B” as side 1; “B-C” as side 2; “C-D as side 3; and “D-A” as side 4
  • Put the selvedge of fabric on the frame, and staple point “A”, and then “B” on side 1 of frame.
  • Stretch fabric from B to C on side 2. Staple pins between points A, B and C.
  • Pull fabric taut at side 4 from side 2 staple point D. Put pins in the entire space between D and A.
  • Pull side 3 from side 1 and staple the entire space between C and D.
  • Be sure space among the stapled pins are close as much as possible and the entire screen is drum-tight or taut.

THE LIGHT EXPOSURE BOX/DEVELOPING BOX

  • It is a kind of wooden/aluminium sheet box with a glass top.
  •  It has an internal fluorescent lights and red/yellow bulb for its lighting system.
  •  It has three small holes on it, to enhance cooling off of heat.
  •  It is always mounted in a darkroom where light is not allowed.
  •  Only red/yellow lights are allowed for they are safety lights that protects materials from damage.
  •  Under safety light an exposed sensitized screen will dry and become stiff and dark ready for exposure.
  •  It is a device used to develop a photographic screen.

THE SCREEN FABRICS

  • The fabric is the part of the screen that carries the image or the stencil.
  •   Screen fabrics are made from either natural fibres such as silk or synthetic fibres such as polyester or nylon.
  •   Fabrics are classified as multifilament or monofilament materials.
  •   Multifilament fibres are made from strands of fibres twisted together into threads.

The monofilament fibres on the other hand, are woven from single round strands

  • Multifilament strands are coarser and thicker than monofilament strands.
  •   Multifilament strands can easily be destroyed by many abrasive or chemical resist inks.
  •   Man-made multifilament strands like polyester are more slippery    than silk.
  •  Man-made multifilament strands are stronger and useful for works requiring critical registration.
  •     Man-made multifilament strands can withstand many abrasive types of ink and pass uniform layer of ink.
  •   To improve the reception for highly slippery synthetic fabrics like polyester, nylon, wire mesh, washing with bleach and water after stretching must roughen them.
  •   The cheapest type of screen fabric is called organdie.

HOW TO PREPARE SCREEN STENCILS

There are three major methods used to prepare screen stencils:

  • Paper stencil/Universal screen method
  • Hand blocking/Lacquer method
  • Photographic methods: Solar energy, Bulb and Light box

PAPER STENCIL/UNIVERSAL SCREEN METHOD

  • Prepare a comprehensive layout of the image or design on a bond paper to the required size of the stencil.
  • Measure and cut cardboard/profilm/newsprint/bond paper to the exact size of the screen.
  • Transfer the design unto the cardboard/profilm/newsprint/bond paper or set out the design direct unto the sheet in right reading.
  • Cut out the design to get the stencil.

Stick the stencil to the back of the screen with cellotape/staple pins. The screen is ready for printing

Hand blocking/Lacquer/Filler method

  • Make direct setting out of the design onto the screen in right reading with pencil or transfer the design from a setting out.
  • Block all the negative or positive parts of the design on the fabric by coating with any of the following transparent materials: Lacquer, polish, vanish, P.V. adhesive (white glue),acrylic paint or wax. The blocking material should be thinned to a medium consistency and applied liberally with a fine brush. Two coats are preferable to achieve complete coverage.

Allow the blocking material to dry thoroughly to make the screen ready for printing

READ MORE ABOUT SCREEN

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