What are different types of screen printing films and emulsions?
What is the process for screen printing?
Also known as silkscreen printing, screen printing is accomplished by forcing ink through a stencil attached to a piece of woven fabric stretched over a frame.
What types of surfaces can be used for screen printing?
Screen printing can be done on a variety of surfaces, including fabric, paper, glass, wood, metal, and plastic.
What type of fabric is used for screen printing?
The most commonly used fabric in screen printing is either monofilament or multifilament polyester.
Which type of fabric is best for my project?
Monofilament fabric is woven of a single thread. It is uniform in weave, giving a smoother ink flow that results in a sharper print. Multifilament fabric is woven of a twisted strand thread. It is less uniform in weave, but has more tooth for easier adhering of stencils and heavier ink deposit.
How are fabric mesh counts determined?
Monofilament fabric mesh count is determined by the number of threads per linear inch. The fewer threads per inch, the larger the size of the openings and the more space for ink to get through the fabric. Monofilament fabrics are designated by a number, such as 86 or 109.
Multifilament mesh size is determined by thread size. The number of threads per square inch stays the same. Multifilament fabric is indicated by a number followed by an XX — for example, 8XX or 10XX.
The following shows a rough equivalent between monofilament and multifilament fabrics:
Monofilament Multifilament 86 6xx 109 8xx 124 10xx 140 12xx 180 14xx 232 16xx
How do I create a stencil for screen printing?
Stencils can be created from paper, hand-cut film, and photographs.
What is the process for cutting film?
Cut a piece of film at least 1" larger than your artwork. Tape the film over your design on your work surface, with the film side up (not the glossy backing side). You can see through it to trace your artwork.
Using a craft knife, carefully cut along the edges of the design. Make sure not to cut through the backing sheet. Your artwork should be as simple as possible when you are just starting out — heavy line drawings, bold block lettering, free-form shapes, or geometrics that can be cut with a ruler work best.
Gently lift and peel away the shapes that you want to print. The film that is left will seal off the rest of the screen so that ink cannot pass through.
Which type of hand-cut film should I use?
If you want to print with waterbased inks, use lacquer-based film which requires strong flammable solvent to make it adhere to the screen. Use caution and good ventilation. Once the screen is ready, you can print with any waterbased or solvent-based inks except lacquer, vinyl, or plastisol.
If you want to print with lacquer, vinyl, plastisol, or solvent-based ink, use watersoluble film. It adheres to the screen with cool water and washes out with warm water when the job is done.
How do I adhere film to my screen?
Place the film right side up on a built-up surface, such as several layers of newspaper or cardboard, that is slightly smaller than the frame. Place the frame on top of the film. Weight the frame with ink cans or similar items so that the film makes good contact with the screen.
Using a lint-free cloth or sponge saturated with adhering solvent or water, blot the screen but do not rub. Get the film just wet enough to adhere. It will look darker where it has adhered properly.
Stand the frame up and use a fan to dry it. After 20 or 30 minutes, try peeling the backing sheet off. It will come off easily if ready. Use block-out and screen tape to seal off the rest of the screen and you're ready to print.
What is the advantage to photographic screen printing?
The advantage to photographic screen printing is that virtually anything you create in black and white (or black and clear) can be reproduced by this process. You must start with a film positive for each color you are printing in.
How can I convert my artwork to a film positive?
A film positive is required for use during the photographic screen process. It consists of an opaque image on a transparent sheet, such as acetate or prepared acetate, Mylar, or copier film. You can use vinyl stick-on letters, transfer lettering, India ink, or Rubylith masking film. You can also create a design on a computer and print it on a laser printer film.
A commercial printing company can convert your artwork to a film positive if you are unable to make your own. In order for any design to screen print well, your image must be sharp and high contrast. If your colors are going to overlap, you need a film positive and a screen for each color. If not, you can use one screen, block out areas with masking tape, and print your colors progressively.
Which photo screen printing method should I use?
There are two methods of photo screen printing.
With the direct method, the photo-sensitive film or liquid emulsion is applied to the screen, allowed to dry, and then exposed to the artwork (film positive) with the proper light source. There are direct liquid emulsions suitable for either solvent or waterbased inks, or both. Ulano CDF direct films are available for either type of ink.
With the indirect method, the photo-sensitive film is exposed to the artwork first, developed in developing solution or water, and then applied to the screen while it is still wet. The indirect method is only suitable for use with solvent-based inks.
How do photo-sensitive films and emulsions work?
All photo materials are sensitive to ultraviolet (UV) light. The black parts of your film positive protect those parts of the stencil that you want to print from being affected by the UV light.
After exposing your film or emulsion to the light, in contact with your film positive, these protected areas are washed out, leaving the hardened, non-image area of the stencil to seal the screen fabric and allow ink to pass through only the washed-out areas.
What are the different types of exposures?
Sunlight costs nothing but is unpredictable.
Photoflood, 150 watt, or 250 watt bulbs are inexpensive, good for bold designs, and fairly dependable. Bulbs with higher wattage require shorter exposure time. However, bulbs may need to be changed often.
Blacklight is a moderately expensive yet very dependable method that delivers excellent results with fine detail and short exposure time.
Self-standing quartz halogen exposing units are very expensive but the best source for professional, continual use.
What is the block-out method and when should it be used?
Similar to the hand-cut method, with the block-out method a brush is used to paint liquid block-out directly on your screen in the areas that you don't want to print, leaving open the areas where you want ink to pass through. In other words, the block-out replaces the film. Use lacquer-based block-out for waterbased inks and waterbased block-out for solvent-based inks. Be sure to properly prepare your screen by degreasing and abrading. Choose a screen mesh in a medium range — 140 or 12XX count.
What is the tusche method and when should it be used?
Tusche is a black, waxy substance in liquid or solid crayon or pencil form that you use to paint or draw directly onto your prepared screen in a positive fashion. The areas you paint will be the areas that print. After the tusche is applied, coat the entire screen with a 50/50 mixture of hide glue and water or 50/50 gum arabic and water. Let that dry, rub out the tusche with turpentine, and you're ready to print. This method requires solvent-based inks.
What is the drawing fluid/screen filler method and when should it be used?
The drawing fluid/screen filler method works like the tusche method, in that the drawing fluid acts as the tusche and the screen filler acts as the glue mixture. The benefit to this method is that the drawing fluid is washed out with cold water and the screen filler can be removed with hot water — turpentine is not needed. Any waterbased ink can be used. This is method is particularly suited for the classroom.