Sunday, April 25, 2010

Screen Printing Info Two: Screen Materials

Frames
There are two types of screen frames, metal and wood. Metal frames, both static (solid) and retentionable, have become the industry standard. Retentionables do not require the use of adhesive products.
Metal frames have been replaced by wood because they do not warp from water like wood frames do. The most commonly used types of wood are cedar and pine. Pine is preferred because it is more water resistant while it is light weight.
Metal screens are made out of aluminum or steel. Aluminum is commonly preferred because it is light weight, yet sturdy. There are some applications where steel is preferred such as very large printing frames used for long printing runs.

Fabric
Screen making - there are two types of threads for screen fabric:
  • Monofilament - single strands weaved into fabric
    (view image)
    • primarily used in commercial printing and other applications
    • Advantage: Monofilament is easier to clean than multifilament
  • Multifilament - multiple strands wound together like a rope, then weaved into fabric
    (view image)
    • primarily used in textile printing.
    • Disadvantage: ink tends to build up on screen, more difficult to clean Monofilament mesh has become the industry standard
Fabric Types
Today commercial screen printing primarily uses 4 types of fabric for making screens, silk, cotton organdie, nylon, and polyester. Silk was the original material used to make screens for screen printing. By far the most widely used fabric is monofilament polyester followed by multifilament polyester and nylon.
  • Silk - multifilament weave
    • loses taughtness with frequent use
    • reclaiming chemicals containing bleach or chlorinated solvents destroy the silk
    • today silk is primarily used for printing art, not commercial use as before
  • Cotton Organdie - multifilament weave
    • same disadvantages as silk
  • Nylon - multifilament or monofilament
    • good for stretching
    • compared to polyester, lacks stability
    • less rigid than polyester
    • unsuitable for closely registered colors
  • Polyester - multifilament or monofilament (calendared monofilament polyester, metallized monofilament polyester)
    • primary material used in commercial screen printing
    • Polyester is strong and stable when stretched
  • Other screen materials - carbonized polyester
    • glass
    • wire mesh
    • stainless steel
Screens made of the same material can differ in thread diameter, number of threads-per-inch, and choice of mono- or multifilament fibers. The need for various characteristics such as wearability and dimensional stability will help determine the fabric selected for a particular screen printing job. Diameter of mesh thread and number of threads per inch determine the amount of ink transferred to the substrate during the printing process.

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