How to Print Film Positives for Sharp Screen Printing Stencils
The best screen printing stencils start with high quality film positives – here are some tips for producing them!
Transferring your artwork to film positives begins with processing your digital artwork the right way and requires the proper printing materials and the right ink. The goal is to create a completely opaque film positive that will block out light as you expose your screens to create a crisp, clear stencil.
Prepare Your Digital Image
Most of the work of creating a film positive happens on your computer, within your preferred artwork program.
Establish Your Settings
Once you have your image ready, you will check your image settings to make sure the settings are in line with your print project. Your resolution should be set to 300 dots per inch (DPI), and you’ll want to make sure that the image’s measurements match the desired dimensions of your print and are sized properly for your printer. Depending on the type of print you’re completing, you may need to make some additional adjustments to your image settings.
Separate Your Colors
The bulk of the time that you spend preparing your film positives will be spent separating the colors in your image. The exact process for doing this will depend on which artwork program you’re using, but the basic premise will remain the same: Isolate each print color onto its own “layer.” This allows you to print a separate film positive and create an individual screen for each color you use. Then, change the color on each layer to pure black for printing the positive.
Add Registration and Center Crop Lines
Once your artwork has been adjusted for printing, there’s one more step you’ll want to take: Add registration and center crop lines to each image layer. The registration and center crop lines will allow you to line up your film positives to be sure of your registration.
Use the Right Materials
Making film positives only requires two materials: the film and the ink. You’ll want to make sure you’re using the right types of film and the right types of ink to print effective film positives.
Finding the Right Film
While there are many different types of printing films, screen printers who rely on inkjet printers for printing positives most often use inkjet film or laser vellum. Inkjet film is preferred because it’s sturdier and more likely to take on an opaque print image. Vellum is less sturdy, but also much cheaper. It can be used for larger images or images that don’t have as much fine detail.
Thermal films and image setter films create the darkest prints, but these films require expensive specialty equipment. Some larger shops will use the more expensive equipment to create the higher quality films. For screen printers who want the higher quality positives without investing in the equipment, thermal or image-setter positives can be ordered from some print shops.
Choosing the Right Ink
Printer ink comes in two varieties: pigment-based and dye-based. Dye-based ink makes for a more opaque print and a better film positive. However, it’s important to make sure that your film and your ink are compatible; some films are made to be used with dye-based inks and others with pigment-based inks. For the best positives, you need to make sure that your ink and your film will work together to make the most opaque image possible.
Consider RIP Software
At this point, with your digital image prepared and the right printing materials on hand, you might be ready to send your job to the printer. There’s one more consideration, though, if you’re looking to make crisp, opaque film positives that result in detailed images. Many screen printers use RIP (raster image processing) software to finalize their images and set up their printers. RIP software helps to print clearer film positives for halftone prints or process jobs and can allow you to control how the ink is printed onto your film, among other things. It’s possible to create good film positives without RIP software, but RIP software can help you to increase the definition and the opacity of your films, and it might be necessary if you print a lot of halftone, process or highly detailed projects.
Creating film positives can be one of the most intimidating elements of the screen printing process, and improper production of film positives can put a wrench in your production process. However, once you master the process, you’ll be able to produce opaque, well-defined film positives every time.
Looking for more tips on how to keep your screen preparation top notch? Check out these blog posts:
- Preparing Your Screen Printing Screens for Sharp Stencils
- Get Crisp Screen Printing Stencils with the Right Exposure Unit
- Preparing Your Screens the Right Way: Screen Printing Emulsion Techniques and Timing
Or give us a call – we’re never too busy to talk screen printing!