CRAFTS OF INDIA / SCREEN PRINTING / TECHNIQUE

CRAFTS OF INDIA / SCREEN PRINTING / TECHNIQUE

- Initially a screen is stretched tightly over a frame. The mesh could be made of nylon or other synthetic polymer. The frame would be of wood or aluminium.

- Tension of the mesh could be checked with a tension meter. The unit of tension is Newton per centimeter or N/cm.

- A stencil is formed by blocking off parts of the screen in the negative image of the design to be printed; i.e. the open spaces are where the ink will appear on the substrate.

- Before printing is done, a pre-press process is undertaken. Pre-process has an emulsion put across the mesh, the exposure unit burns away the excess emulsion and leaves behind a clean area in the mesh with the identical shape as the desired image.

- The surface to be printed or ‘pallet’ is coated with a wide pallet tape. The pallet tape is thus protected from any unwanted ink leaking through the screen and staining the pallet.

- Next the screen and frame are lined with a tape meant to prevent the low viscosity inks to leave unwanted marks upon the substrate.

- The last process in the 'pre-press' is blocking out any unwanted 'pin-holes' in the emulsion. If these holes are left in the emulsion, the ink will continue through and leave unwanted marks. To block out these holes, materials such as tapes, speciality emulsions and 'block-out pens' may be used effectively.

- The screen is placed atop a substrate. Ink is placed on top of the screen, and a flood bar is used to push the ink through the holes in the mesh.

- The operator begins with the fill bar at the rear of the screen and behind a reservoir of ink. The operator lifts the screen to prevent contact with the substrate and then using a slight amount of downward force pulls the fill bar to the front of the screen.

- This effectively fills the mesh openings with ink and moves the ink reservoir to the front of the screen.

- The operator lifts the screen to prevent contact with the substrate and then using a slight amount of downward force pulls the fill bar to the front of the screen. This effectively fills the mesh openings with ink and moves the ink reservoir to the front of the screen.

- The operator then uses a squeegee (rubber blade) to move the mesh down to the substrate and pushes the squeegee to the rear of the screen. The ink that is in the mesh opening is pumped or squeezed by capillary action to the substrate in a controlled and prescribed amount. i.e. the wet ink deposit is proportional to the thickness of the mesh and or stencil.

- As the squeegee moves toward the rear of the screen the tension of the mesh pulls the mesh up away from the substrate (called snap-off) leaving the ink upon the substrate surface.

- The screen is placed atop a substrate. Ink is placed on top of the screen, and a flood bar is used to push the ink through the holes in the mesh.