how to print Silk-screen manually
INTRODUCTION
There are 5 basic steps to photo screen making and printing:
1. Artwork Preparation
2. Coating the Screen
3. Exposing the Screen
4. Developing the Screen
5. Printing
This manual will guide you through the 5 steps with graphic representations and descriptions. Before work is begun, however, you will need to prepare the necessary materials for silk screening.
Necessary Materials For Silk Screening
* Screen, 2” larger on each side than artwork to be screened (Always coordinate mesh size to ink requirements)
* Squeegee, 1” smaller than inside screen dimensions
* Ink (Choose according to printing surface and desired qualities) Photo Emulsion and Sensitizer
Tape (see TAPING THE SCREEN for type you need): Paper, Plastic or Masking
Newspapers
Household Bleach
Household Hydrogen Peroxide
Scrub Brush, Soft Bristle
Bulb – Preferably a 150 Watt Flood Bulb
Measuring Cup
Old Rags or Towels (Paper or Cloth)
A Piece of Glass Large Enough to Support the Screen and Allow for Propping on
Both Sides Without Interference With the Light Source
Spatula – Approximately 1”
Cardboard – Pieces Cut to About 3” x 6” (For Ink Cleanup)
Opaque Marker, Technical Pen (Use Ink For Plastic Sheets), Graphic Arts Tape, India Ink, Ruby Film, and Stencil Knife (see ARTWORK PREPARATION for full description of choices)
For Multicolor Work Only, Registration Pins and a Standard 1/4” diameter hole puncher
For Multicolor Textile Printing Only – Eye Bolts, L-Angles, wood for Contact Bar and Platen (See “T” Shirt Platen)
ARTWORK PREPARATION
The first and most important step in successful screen making is artwork preparation. In photo screen making and screen printing all the steps that follow artwork preparation depend on accurate duplication of your design. In order to render the exact image you want it is absolutely necessary for your artwork to be opaque. Opaque artwork means you cannot see light through the areas of your artwork that you want to print. Hold your artwork up to the light and check this to insure no light shows through the areas you darkened. It is very helpful to check opacity on a light box.
The opacity of your artwork is crucial to obtaining a clean well defined stencil. The
artwork you create will become part of the screen and this is called a stencil. The opaque materials you use to create your artwork will stop the light from getting to the photo emulsion, which will be coated onto the screen, and when you shoot the screen the light will not be able to penetrate the opaque materials. If light does not get to the photo emulsion, it will not harden in that area. When the screen is developed or washed out, the parts that were not exposed to light will wash out. Later during printing, the ink will pass through these undeveloped or washed out areas in the screen and the ink will print the exact image of your design.
Basically there are many different materials that can be used to prepare artwork for a photo screen, however they must all be opaque mediums and they must work on clear acetate or clear polyester (plastic sheets). Materials such as
India Ink
Red Ruby Masking Ink
Ink For Acetate Pressure-sensitive Lettering Dry Transfer Lettering
Opaque Markers That Work On Any Surface
Technical Pens Graphic Art Tapes Ruby Tape
Ruby or Amber Film Shading Film Stencil Knife
Actually any material that will filter out ultra violet light will work to create a photo screen because ultra violet light causes the photo emulsion to cross link and become a waterproof coating or stencil.
Creating Artwork.
Making Monocolor Artwork
To make artwork, simply tape your drawing down to the table and tape a sheet of acetate over it. Now you can trace your image with any of the opaque mediums mentioned. You can also create directly on the acetate without tracing. If you choose to make words, you will need a grid sheet or piece of paper with horizontal lines that are straight so your lettering can be transferred to the plastic sheet in a uniform patter (See Diagram). Burnish the transfer lettering directly onto the acetate but be sure to put clear Scotch tape over it when you are finished so the letters will not
chip or peel while you are handling or storing the sheet.
Making Multicolor Artwork
When making multicolor artwork, exact overlaying of colors is crucial to render a print that will not have spaces between colors. This is called registration of colors. Overlapping of colors is called trapping and is crucial to good registration. Good traps mean less difficulty in registering one color to another when printing. All the colors that are supposed to meet or touch each other will fall in the right places in your design.
To make a good trap, the light colors should extend slightly into the dark colors. When printing, the light colors are printed first and the dark colors are printed over them, thus reducing the overlap and rendering the exact size of the color shape in your artwork. Therefore, each acetate will contain a separate color. The size of the overlap depends upon the width of the adjacent or outline color. When an entire pattern is covered by an outline which pulls the images together, the underlying colors must overlap into the outlined area but not surpass the outline.
First, analyze the number of colors in your design and note where each color appears in the entire image. Each color will need a separate acetate or clear polyester sheet.
To make multicolor artwork, you will need registration pins, a 1/4” diameter hole puncher and a separate acetate or clear polyester sheet for each color. Before any work has begun, gather the sheets together and punch a hole in the upper right hand corner, at least 2” above your artwork, and insert a registration pin. Now punch a hole in the upper left hand corner and insert another registration pin (See Diagram).
Tape the pins to the drawing board or a table and remove the plastic or acetate sheets. Tape your artwork to the board and place the first acetate on the registration pins. Using a marker, technical pen or other opaque medium, trace the first color of your design. When finished, remove the acetate and replace with the next acetate. Trace the next color. Continue this process until all the colors are traced on separate acetates (See Diagram).
After you separate all the colors (this would include the outline that pulls the design together, if your artwork calls for an outline) place all acetates on the registration pins with the overall outline on top. Your overall outline or pattern that brings the design together as a whole should not show spaces between colors when you hold the acetates up to the light. It may help to work on a light box.
Summary
1. Analyze the number of colors in your design.
2. Use a separate acetate for each color.
3. Register all acetates simultaneously to each other by punching holes in the plastic sheets with a 1/4” diameter standard hole puncher and insert pins. Punch the first hole and insert the pin before punching the second hole and inserting the pin.
4. Tape the artwork to the drawing board. Tape the registration pins 2” above the artwork.
5. Place the first acetate on the pins and copy the first color with an opaque medium. Remove the acetate when completed.
6. Place the next acetate on the pins and copy the next color. Remove this acetate and continue until all colors are separated.
7. When colors meet, trap light colors by extending them beyond the original artwork and into the darker or neighboring colors. However, the overall outline color that pulls the image together should not be surpassed. This master or outline color should bring the extended colors back down to their original shape and fit perfect as in the original artwork.
Important Things to Remember
Proportion your artwork according to the space you are printing on. For example children’s “T” shirts have a smaller print area than adult “T” shirts and your artwork should be reduced to fit that space. When printing on paper you may want to leave a border around the edges of the paper. Do not print to the end of the paper stock, because the image will not print clearly. (Also, you will not be able to pick the paper up without getting ink on your fingers!)
Opaque Areas in your artwork or areas you cannot see through will print. Light will not pass through opaque artwork and the photo emulsion will not cross link during exposure time. These areas will wash out when you develop the screen and while you are printing; the ink will pass through these washed out areas and onto your stock.
Transparent Areas around your artwork or areas you can see through will not print. Light will pass through the transparent or blank areas around your artwork and expose the photo emulsion causing a chemical cross linking that will harden around your artwork. Your artwork will actually be formed by this process and become part of the screen stencil.
Positives and Negatives
What are positives and negatives? Generally speaking, a positive is the image that is not part of the background. A negative is the background which is printed to create the image.
For example, in the images below, the cash register’s shape or form is outlined and thus defined as a positive picture of the object. The apple and witch are also positive images that will print as they are drawn.
The SOS and the globe are defined or shaped by the areas around them and they are negative representations of the objects. The opaque areas that surround the SOS and the globe are the parts that will print. Notice, the continents on the globe are positive images on the negative globe. The transparent areas which are the images shaped or formed by the background will not print. Ink will only pass through opaque areas in the artwork.
Film positives and film negatives can be made by using a process camera and
photographic artwork which is in black and white and on paper. These work the same way as hand made positives and negatives and print as stated above.
It is important to keep in mind the qualities of the ink you are using and the substrate you intend to print on when making positives and negatives. Some inks dry slowly and large deposits of ink will take long to dry. This may affect the amount of time it takes to complete a project as well as what difficulties a specific design may introduce.
COATING THE SCREEN
Preparation
Once you make your artwork, the next step in the process is coating the screen. It is very important to wash the screen mesh to remove all sizing before you apply the photo emulsion. If there is oil on a mesh from your skin or from handling in the factory where the screen was made, this oil will repel the photo emulsion and you will have spaces in the coating which will ultimately become unwanted open areas in the screen. When it comes time to print, ink will flow through these open areas and be deposited on the stock.
Using your scrub brush, gently scrub the screen with soap and water and rinse. Then with an abrasive cleanser, one which does not contain bleach, such as Bonami, gently scrub the screen again. Be sure to rinse thoroughly. Allow the screen
to dry completely (a fan will greatly decrease drying time). Now your screen will be more absorbent and the photo emulsion will better adhere to the mesh.
Photo Emulsion
Working in a dimly lit area, mix 4 parts photo emulsion to 1 part sensitizer. For example, 4 ounces emulsion with 1 part sensitizer. Once mixed, this solution is light sensitive with a short shelf life. Measure small amounts to prevent wastage. The amount of photo emulsion and sensitizer you will need will depend upon the size of the screen you are using. Stir this mixture carefully to prevent air bubbles and allow mixture to stand for about 10 minutes. It is best to work in very dim daylight or use an amber bulb because it is bright but will not affect the chemistry of the photo emulsion.
Store excess photo emulsion and sensitizer mixture in a plastic or glass container at room temperature. Be sure to store in a darkened area. This mixture is good for 3 to 4 days at room temperature and slightly longer if refrigerated. (If storing in refrigerator, use an opaque container which will not allow light to expose the photo emulsion.)
Expose the screen and develop within seven hours after coating it. If you need more time, it can still be exposed up to 24 hours after coating the screen. However, the screen must be stored in a dark area until you are ready to expose it. Save the extra mixture to fill pinholes after the screen has been developed but again keep it in a dark area. CAUTION: Never use photo emulsion on screens made with pure silk fabric mesh.
Reclaiming the Screen or Removing the Photo Emulsion
After printing, many screeners prefer to leave the image on the screen for future use. If you wish to do so, your screen can be stored indefinitely. If however, you choose to remove the image from the screen follow these simple steps:
1. Remove all excess ink and return it to the container.
2. To clean the screen, follow the instructions on the ink can label. For instance, if using water based ink, clean screen with water. If using oil based inks, clean screens with screen wash. It
is very important to get all the ink out of the screen before reclaiming. Any remaining ink will interfere with the chemistry needed to remove the emulsion.
3. Fill a tray or a tub that is larger than the screen with household bleach. Cover the mesh completely. Wait 5 to 10 minutes.
4. With a soft scrub brush, gently rub both sides of the fabric.
5. Stand screen up and sprinkle or spray hydrogen peroxide on both sides. This will create a foaming action. Scrub both sides gently and wait 5 to 10 minutes.
6. Using hot water, preferably with a spray hose, wash the screen.
7. When the screen is thoroughly rinsed, allow it to dry completely and it will be ready for reuse.
If needed, the process may be repeated.
Applying the Photo Emulsion
After mixing the photo emulsion and sensitizer in the exact proportions needed, and allowing the mixture to sit for about 10 minutes, follow the three steps illustrated below.
1. Turn screen to outside and pour a sufficient amount of the mixture along the narrow side of the screen.
2. In a scraping action, use a coating bar or squeegee to spread the mixture smoothly over the entire length of the screen. Scrape coat outside of screen.
3. For a more durable screen, turn over and scrape coat the inside of the screen from bottom to top. Turn over and scrape coat inside of screen.
4. Turning to the outside of the screen, repeat the process but do not add more photo emulsion unless there are streaks and empty spaces.
5. Always apply final coat to the inside of the screen.
Scrape away excess emulsion and return excess to the container. Do not leave a heavy deposit of emulsion on the screen. Apply even coats. Do not leave lumps or streaks on the screen. Be sure the screen that has been coated does not come in contact with anything that will disturb its smooth coat.
There are 5 basic steps to photo screen making and printing:
1. Artwork Preparation
2. Coating the Screen
3. Exposing the Screen
4. Developing the Screen
5. Printing
This manual will guide you through the 5 steps with graphic representations and descriptions. Before work is begun, however, you will need to prepare the necessary materials for silk screening.
Necessary Materials For Silk Screening
* Screen, 2” larger on each side than artwork to be screened (Always coordinate mesh size to ink requirements)
* Squeegee, 1” smaller than inside screen dimensions
* Ink (Choose according to printing surface and desired qualities) Photo Emulsion and Sensitizer
Tape (see TAPING THE SCREEN for type you need): Paper, Plastic or Masking
Newspapers
Household Bleach
Household Hydrogen Peroxide
Scrub Brush, Soft Bristle
Bulb – Preferably a 150 Watt Flood Bulb
Measuring Cup
Old Rags or Towels (Paper or Cloth)
A Piece of Glass Large Enough to Support the Screen and Allow for Propping on
Both Sides Without Interference With the Light Source
Spatula – Approximately 1”
Cardboard – Pieces Cut to About 3” x 6” (For Ink Cleanup)
Opaque Marker, Technical Pen (Use Ink For Plastic Sheets), Graphic Arts Tape, India Ink, Ruby Film, and Stencil Knife (see ARTWORK PREPARATION for full description of choices)
For Multicolor Work Only, Registration Pins and a Standard 1/4” diameter hole puncher
For Multicolor Textile Printing Only – Eye Bolts, L-Angles, wood for Contact Bar and Platen (See “T” Shirt Platen)
ARTWORK PREPARATION
The first and most important step in successful screen making is artwork preparation. In photo screen making and screen printing all the steps that follow artwork preparation depend on accurate duplication of your design. In order to render the exact image you want it is absolutely necessary for your artwork to be opaque. Opaque artwork means you cannot see light through the areas of your artwork that you want to print. Hold your artwork up to the light and check this to insure no light shows through the areas you darkened. It is very helpful to check opacity on a light box.
The opacity of your artwork is crucial to obtaining a clean well defined stencil. The
artwork you create will become part of the screen and this is called a stencil. The opaque materials you use to create your artwork will stop the light from getting to the photo emulsion, which will be coated onto the screen, and when you shoot the screen the light will not be able to penetrate the opaque materials. If light does not get to the photo emulsion, it will not harden in that area. When the screen is developed or washed out, the parts that were not exposed to light will wash out. Later during printing, the ink will pass through these undeveloped or washed out areas in the screen and the ink will print the exact image of your design.
Basically there are many different materials that can be used to prepare artwork for a photo screen, however they must all be opaque mediums and they must work on clear acetate or clear polyester (plastic sheets). Materials such as
India Ink
Red Ruby Masking Ink
Ink For Acetate Pressure-sensitive Lettering Dry Transfer Lettering
Opaque Markers That Work On Any Surface
Technical Pens Graphic Art Tapes Ruby Tape
Ruby or Amber Film Shading Film Stencil Knife
Actually any material that will filter out ultra violet light will work to create a photo screen because ultra violet light causes the photo emulsion to cross link and become a waterproof coating or stencil.
Creating Artwork.
Making Monocolor Artwork
To make artwork, simply tape your drawing down to the table and tape a sheet of acetate over it. Now you can trace your image with any of the opaque mediums mentioned. You can also create directly on the acetate without tracing. If you choose to make words, you will need a grid sheet or piece of paper with horizontal lines that are straight so your lettering can be transferred to the plastic sheet in a uniform patter (See Diagram). Burnish the transfer lettering directly onto the acetate but be sure to put clear Scotch tape over it when you are finished so the letters will not
chip or peel while you are handling or storing the sheet.
Making Multicolor Artwork
When making multicolor artwork, exact overlaying of colors is crucial to render a print that will not have spaces between colors. This is called registration of colors. Overlapping of colors is called trapping and is crucial to good registration. Good traps mean less difficulty in registering one color to another when printing. All the colors that are supposed to meet or touch each other will fall in the right places in your design.
To make a good trap, the light colors should extend slightly into the dark colors. When printing, the light colors are printed first and the dark colors are printed over them, thus reducing the overlap and rendering the exact size of the color shape in your artwork. Therefore, each acetate will contain a separate color. The size of the overlap depends upon the width of the adjacent or outline color. When an entire pattern is covered by an outline which pulls the images together, the underlying colors must overlap into the outlined area but not surpass the outline.
First, analyze the number of colors in your design and note where each color appears in the entire image. Each color will need a separate acetate or clear polyester sheet.
To make multicolor artwork, you will need registration pins, a 1/4” diameter hole puncher and a separate acetate or clear polyester sheet for each color. Before any work has begun, gather the sheets together and punch a hole in the upper right hand corner, at least 2” above your artwork, and insert a registration pin. Now punch a hole in the upper left hand corner and insert another registration pin (See Diagram).
Tape the pins to the drawing board or a table and remove the plastic or acetate sheets. Tape your artwork to the board and place the first acetate on the registration pins. Using a marker, technical pen or other opaque medium, trace the first color of your design. When finished, remove the acetate and replace with the next acetate. Trace the next color. Continue this process until all the colors are traced on separate acetates (See Diagram).
After you separate all the colors (this would include the outline that pulls the design together, if your artwork calls for an outline) place all acetates on the registration pins with the overall outline on top. Your overall outline or pattern that brings the design together as a whole should not show spaces between colors when you hold the acetates up to the light. It may help to work on a light box.
Summary
1. Analyze the number of colors in your design.
2. Use a separate acetate for each color.
3. Register all acetates simultaneously to each other by punching holes in the plastic sheets with a 1/4” diameter standard hole puncher and insert pins. Punch the first hole and insert the pin before punching the second hole and inserting the pin.
4. Tape the artwork to the drawing board. Tape the registration pins 2” above the artwork.
5. Place the first acetate on the pins and copy the first color with an opaque medium. Remove the acetate when completed.
6. Place the next acetate on the pins and copy the next color. Remove this acetate and continue until all colors are separated.
7. When colors meet, trap light colors by extending them beyond the original artwork and into the darker or neighboring colors. However, the overall outline color that pulls the image together should not be surpassed. This master or outline color should bring the extended colors back down to their original shape and fit perfect as in the original artwork.
Important Things to Remember
Proportion your artwork according to the space you are printing on. For example children’s “T” shirts have a smaller print area than adult “T” shirts and your artwork should be reduced to fit that space. When printing on paper you may want to leave a border around the edges of the paper. Do not print to the end of the paper stock, because the image will not print clearly. (Also, you will not be able to pick the paper up without getting ink on your fingers!)
Opaque Areas in your artwork or areas you cannot see through will print. Light will not pass through opaque artwork and the photo emulsion will not cross link during exposure time. These areas will wash out when you develop the screen and while you are printing; the ink will pass through these washed out areas and onto your stock.
Transparent Areas around your artwork or areas you can see through will not print. Light will pass through the transparent or blank areas around your artwork and expose the photo emulsion causing a chemical cross linking that will harden around your artwork. Your artwork will actually be formed by this process and become part of the screen stencil.
Positives and Negatives
What are positives and negatives? Generally speaking, a positive is the image that is not part of the background. A negative is the background which is printed to create the image.
For example, in the images below, the cash register’s shape or form is outlined and thus defined as a positive picture of the object. The apple and witch are also positive images that will print as they are drawn.
The SOS and the globe are defined or shaped by the areas around them and they are negative representations of the objects. The opaque areas that surround the SOS and the globe are the parts that will print. Notice, the continents on the globe are positive images on the negative globe. The transparent areas which are the images shaped or formed by the background will not print. Ink will only pass through opaque areas in the artwork.
Film positives and film negatives can be made by using a process camera and
photographic artwork which is in black and white and on paper. These work the same way as hand made positives and negatives and print as stated above.
It is important to keep in mind the qualities of the ink you are using and the substrate you intend to print on when making positives and negatives. Some inks dry slowly and large deposits of ink will take long to dry. This may affect the amount of time it takes to complete a project as well as what difficulties a specific design may introduce.
COATING THE SCREEN
Preparation
Once you make your artwork, the next step in the process is coating the screen. It is very important to wash the screen mesh to remove all sizing before you apply the photo emulsion. If there is oil on a mesh from your skin or from handling in the factory where the screen was made, this oil will repel the photo emulsion and you will have spaces in the coating which will ultimately become unwanted open areas in the screen. When it comes time to print, ink will flow through these open areas and be deposited on the stock.
Using your scrub brush, gently scrub the screen with soap and water and rinse. Then with an abrasive cleanser, one which does not contain bleach, such as Bonami, gently scrub the screen again. Be sure to rinse thoroughly. Allow the screen
to dry completely (a fan will greatly decrease drying time). Now your screen will be more absorbent and the photo emulsion will better adhere to the mesh.
Photo Emulsion
Working in a dimly lit area, mix 4 parts photo emulsion to 1 part sensitizer. For example, 4 ounces emulsion with 1 part sensitizer. Once mixed, this solution is light sensitive with a short shelf life. Measure small amounts to prevent wastage. The amount of photo emulsion and sensitizer you will need will depend upon the size of the screen you are using. Stir this mixture carefully to prevent air bubbles and allow mixture to stand for about 10 minutes. It is best to work in very dim daylight or use an amber bulb because it is bright but will not affect the chemistry of the photo emulsion.
Store excess photo emulsion and sensitizer mixture in a plastic or glass container at room temperature. Be sure to store in a darkened area. This mixture is good for 3 to 4 days at room temperature and slightly longer if refrigerated. (If storing in refrigerator, use an opaque container which will not allow light to expose the photo emulsion.)
Expose the screen and develop within seven hours after coating it. If you need more time, it can still be exposed up to 24 hours after coating the screen. However, the screen must be stored in a dark area until you are ready to expose it. Save the extra mixture to fill pinholes after the screen has been developed but again keep it in a dark area. CAUTION: Never use photo emulsion on screens made with pure silk fabric mesh.
Reclaiming the Screen or Removing the Photo Emulsion
After printing, many screeners prefer to leave the image on the screen for future use. If you wish to do so, your screen can be stored indefinitely. If however, you choose to remove the image from the screen follow these simple steps:
1. Remove all excess ink and return it to the container.
2. To clean the screen, follow the instructions on the ink can label. For instance, if using water based ink, clean screen with water. If using oil based inks, clean screens with screen wash. It
is very important to get all the ink out of the screen before reclaiming. Any remaining ink will interfere with the chemistry needed to remove the emulsion.
3. Fill a tray or a tub that is larger than the screen with household bleach. Cover the mesh completely. Wait 5 to 10 minutes.
4. With a soft scrub brush, gently rub both sides of the fabric.
5. Stand screen up and sprinkle or spray hydrogen peroxide on both sides. This will create a foaming action. Scrub both sides gently and wait 5 to 10 minutes.
6. Using hot water, preferably with a spray hose, wash the screen.
7. When the screen is thoroughly rinsed, allow it to dry completely and it will be ready for reuse.
If needed, the process may be repeated.
Applying the Photo Emulsion
After mixing the photo emulsion and sensitizer in the exact proportions needed, and allowing the mixture to sit for about 10 minutes, follow the three steps illustrated below.
1. Turn screen to outside and pour a sufficient amount of the mixture along the narrow side of the screen.
2. In a scraping action, use a coating bar or squeegee to spread the mixture smoothly over the entire length of the screen. Scrape coat outside of screen.
3. For a more durable screen, turn over and scrape coat the inside of the screen from bottom to top. Turn over and scrape coat inside of screen.
4. Turning to the outside of the screen, repeat the process but do not add more photo emulsion unless there are streaks and empty spaces.
5. Always apply final coat to the inside of the screen.
Scrape away excess emulsion and return excess to the container. Do not leave a heavy deposit of emulsion on the screen. Apply even coats. Do not leave lumps or streaks on the screen. Be sure the screen that has been coated does not come in contact with anything that will disturb its smooth coat.
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