How screen-printing works

Gerv Harvill and Rik Cooper of Mission Print explain he process of creating this screen printing poster.

The artwork shown here was supplied as full-colour art. Rik Cooper explains how he prepared the original image for screen-printing.

“Firstly I had to pick the Black using Photoshop’s Color Range,” says Cooper. “I then used a greyscale image, imported it into Illustrator and used the Live Paint Bucket to create a vector version of the main black artwork. I then redrew the other colours, placing the photo in the background.”

He continues: “With the print process going from light colours to dark as I layered up the artwork, using a 0.25mm trap where needed. Finally, I used overprint preview to check my layers properly before sending to print.”

1. Artwork Separation

After receiving the raw artwork, Mission Print separates it into spot colours. They discuss options with the client for paper, print size and borders, watermark postion and ink finish. The separated file is then sent to the client for sign-off.

2. Film Output

Gerv Harvill says: “Once the file has been processed and approved by our print manager it’s ready to run to film. Our designer checks the film before taking it to the screen room.”

3. Preparing the stencil

“Our screenmaker tapes the film positive into position on the reverse of the screen,” explains Harvill. “The screen is exposed to light in one of our exposure units, the film is then removed and the screen washed in warm water.”

The areas of screen emulsion exposed to light through the clear areas of the film remain intact, while the areas where the black areas of the film prevented light reaching the emulsion are washed away.

“The screen is then dried and any imperfections in the stencil are corrected.”

4. Mixing the inks

Meanwhile the printer mixes the inks. They will choose between water-based, solvent or UV inks depending on the piece.

“Colours will be matched to Pantone references chosen by the client,” adds Harvill. “Colours can vary through different screen meshes and onto different substrates and also on drying. The printer will sometimes spend longer matching a colour than printing the edition.”

5. Printing the job

The printer sticks the film onto the paper in the right position. The paper is then laid on the print table and the screen aligned to print where the film is on the paper. The printer references two edges of the paper with lay stops to maintain consistent registration throughout the edition.

“During the edition the printer will overprint previous test sheets to ensure there’s no movement and that the print position is consistent,” says Harvill. “Additional colours are printed in sequence – usually from light to dark – until the edition is complete. In most cases we prefer to produce a sample for approval after which adjustments can be easily made before printing.”

6. Drying and packing

Solvent and water-based inks are left to dry for a couple of hours; UV inks are cured under UV light.

“Once dry the edition will be trimmed to size, checked for quality and then carefully packed for shipping or collection,” says Gerv Harvill.

Alice Ross –

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