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SCREEN PRINTING GUIDES · PREPARATION

Film positives: what they are and what they do in screen printing

Before ink reaches a bag, a PVC item or a fabric, the design has to be transferred onto a screen. The film positive is what makes that step possible. Understanding how it works helps you prepare artwork, read a quote and plan repeat orders.

Published 6 min read

In short

  • A film positive is a transparent film with the design printed in opaque black.
  • It is used to transfer the design onto the screen. It does not print anything itself.
  • As a rule, each colour in the design needs its own film and its own screen.
  • Vector files, actual print sizes and identified colours avoid extra preparation.
  • For a repeat order, identify the previous job and any change to the artwork.

01

What is a film positive?

A film positive is a transparent sheet on which the design to be printed appears in opaque black. It works like a light mask: the black areas block the light and the clear areas let it through.

The film never touches the ink or the finished item. It is a preparation tool, used before printing to transfer the design onto the screen. Because each colour is printed separately in screen printing, a multi-colour design usually needs one film per colour.

AGFA AccuSet 1500 imagesetter with a sheet of film resting on top
Print preparationImagesetter: the equipment that outputs the digital artwork onto the film that becomes the film positive.

02

How it is used in the process

There are four main stages between the file sent by the client and the printed item. The film positive sits in the middle, linking the digital artwork to the screen.

  1. 01

    Final artwork

    The file is checked and set to the actual print size. If the design has several colours, it is separated colour by colour.

  2. 02

    Film positives

    Each colour is output onto its own film, with that part of the design in opaque black.

  3. 03

    Screen exposure

    The screen, coated with light-sensitive emulsion, is exposed with the film on top. Where the film is black, the emulsion does not harden and is later washed out with water, leaving the mesh open.

  4. 04

    Printing

    The squeegee pushes ink through the open areas of the mesh and the design is transferred to the substrate. Each colour has its own pass.

Simplified diagram of the process for a two-colour design.
Illuminated exposure unit with a screen held down by weights and, next to it, an AGFA Rapiline film processor
Print preparationExposure unit: the screen and film are held in contact by weights while the light fixes the design in the emulsion. Alongside it, the film processor.

03

Film positive or screen: what is the difference?

They are two different items, used at different stages, and they are often confused. The film is used to transfer the design; the screen is used to print it.

Film positive

What it is
A transparent film with the design in opaque black.
What it does
Transfers the design onto the screen during preparation.
Contact with ink
No.
When it must be remade
When the design, size or colour separation changes.

Screen

What it is
A frame with stretched mesh, coated with emulsion.
What it does
Prints: ink passes through the open areas of the mesh.
Contact with ink
Yes, for every printed item.
When it must be remade
When the exposed design changes or the job needs a different screen preparation.
Screen printing screens of various sizes leaning against a wall, some coated with yellow and purple emulsion
Print preparationScreens in various sizes. The yellow and purple ones are coated with emulsion; on the white ones you can see the bare mesh.
Screen stretcher with red toggle clamps mounted on a wooden workbench
Print preparationScreen stretcher: the mesh is stretched and fixed to the frame before it is coated with emulsion.

04

How colours and preparation affect the quote

Before the first item is printed, there is preparation work: checking the artwork, producing the films, exposing the screens and registering each colour. That work depends mainly on the design, not on the quantity.

Number of colours
As a rule, each colour needs its own film, its own screen and its own printing pass, with the colours aligned to one another. A three-colour logo needs more preparation than the same logo in one colour.
Size and print positions
The size of the design determines the size of the film and screen. Printing in more than one position, such as front and back, may add preparation and passes.
State of the artwork
A print-ready vector file saves work. A low-resolution image, live text or undefined colours may mean the artwork has to be prepared before the films are made.
Detail and gradients
Very fine lines, small text, photographs and gradients need more care and do not suit every substrate. They are worth assessing before the design is finalised.
Substrate
The colour and texture of the material change how colours appear. On clear PVC, non-woven material or fabric, preparation is planned so that the design reads well.
Quantity
Because preparation happens before production, its share of the cost per item tends to be higher for small quantities.
Black non-woven bag with a logo printed in green and white
Work produced by SERIFILTwo-colour logo on black non-woven material. Each colour had its own preparation.

This guide is not a quote. For an accurate assessment, tell us about the artwork, substrate, number of colours, print size and approximate quantity.

05

Which files to send

The more complete the information, the fewer questions remain before the films are made. Use this list to prepare what you send.

Vector artwork
For example vector PDF, AI, EPS or SVG. Vector files stay sharp at any size.
Text converted to outlines
Convert text to outlines or send the fonts used, to avoid font substitution.
Identified colours
Say how many colours the design has and, if colour matching matters, give a reference for each one, for example Pantone.
Size and position
Final print size and position on the item. A photo or sketch with the position marked helps.
Substrate details
Type of material, colour and, if possible, a photo or sample of the item.
If you only have an image
Send the highest-quality version you have, as JPG or PNG. The artwork may need preparing before going ahead, which is assessed with your request.
Safety warning in three languages printed in black on clear PVC
Work produced by SERIFILSmall text printed on clear PVC. With detail like this, the quality of the file shows in the result.

Each material has its own particularities. The pages on PVC screen printing, fabric screen printing, non-woven bags and footwear components explain what to include in your request.

06

Repeat orders: what to consider

When a job is repeated, part of the preparation may already be done. That depends on what stays the same and should be confirmed case by case.

Identify the previous order
Give the approximate date or reference, or send a photo of the printed item.
Check the artwork is identical
A small change, such as a contact detail, a date or a different size, usually means a new film and a new screen exposure for the colour affected.
Check colours and substrate
Changing the ink colour, the material or the colour of the item may require adjustments, even with the same design.
Ask about previous preparation
Whether films or screens from a previous job can be reused is something to confirm when requesting a quote.
Keep the approved artwork
Keeping the final file makes any repeat easier, even if everything has to be prepared again.

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