Screenprinting 101, Part III
SignIndustry.com - The Online Magazine for the Sign Trade.
Home | Site Map | Buyer's Guide Search  
Event Calendar Article Archive Message Boards Classifieds Product Showcases News Advertise Search Join Now

CATEGORIES
  3-D Signs
  ADA
  Architectural
  Awnings &
  Flexible Face
  Banners
  Business Development
  CNC Routing
  Computer Technology
  Digital Imaging
  Dynamic Digital
  Electric
  Estimating
  Finishing & Lams 
  Flatbed UV
  Garment Decoration
  Installation
  LED Displays
  LED Lighting
  Neon & LED
  Channel Letter
  Outdoor
  Painted Signs
  Screen Printing
   Articles
   Product
   Showcase
   Message Board
   Tips & Tricks
  Sublimation
  Vinyl Signs
  Hot Shots
  Press Releases
  Tips & Tricks
  Industry Resources
  Books
  Event Calendar
  Associations
  Business Center
  Retail Sign Shops
  Advertising Info

Supply 55 BannerPRO, EcoPRO continuous ink supply system, guardian laminators, quickmount


Screenprinting 101, Part III

This is part three of a series of helpful and timely tips for both the beginner and seasoned screenprinter

By John Benedetto

If you have just stumbled into this article, you have missed the first two parts on the basics of Screenprinting. Part I had to do with the business of screenprinting and Part II was on Artwork, UV Paper (use as a film positive), Screens and Washout. These articles are written with the beginner in mind. The information is intended to be general in scope and written on the basics of screenprinting. I am not writing a book by verse, just an expanded outline on the subject

Check It Out!

  • Screen Printing Articles
  • Industry Alert
  • Hot Shots Photo Gallery
  • Message Boards

    Visit Our Advertisers:

  • 3M Commercial Graphics
  • CADlink Technology
  • Clarke Systems
  • Estimate Software
  • International Sign Assoc.
  • JetUSA
  • Matrix Payment Systems
  • SGIA Specialty Graphics Imaging Assoc
  • Supply 55, Inc.


  • Remember my motto, “If it is flat you can print it”. Wood, metal, glass, plastic and paper are a few of the substrates that can be printed. The screens are made the same, just the ink types change. For the scope of these articles our substrate will be cloth such as T-shirts, sweatshirts, jackets, etc. As you may recall, in the last article we prepared a screen and are ready to print.

    Setting the Off Contact (Snap Off)
    You will need to prepare your printer. You will have to set up your machine. If you have a rotary machine you must put your screens into the brackets and secure them.

    The next step is to set the Off Contact Adjustment. I have found in England and Europe they call this adjustment Snap or Snap Off. No matter what you call it, you still have to do it. Simply stated, Off Contact is an air gap between the bottom of the screen (print side) and the top of the item you are printing.

    You need this adjustment so that you can push the mesh of the screen down, by use of a squeegee, to the item you are printing. Push the ink through the openings in the screen onto the substrate. When you are finished, release the downward pressure of the squeegee. This will allow the screen to rise to its beginning position. This should leave the ink on the item and the screen free and clear of the item with no ink stranded between the screen and item, if proper technique is used. The distance of the Snap Off will range from as little as a 1/16” to over 1/4”, depending on a few factors.

    These factors can be one or all of the following: First, the type of substrate to be printed. Second, the type of screens you are using (metal, plastic or wood). Wood tends to have less tension so you will need a bigger Snap Off than with a high-tension metal screen. And last but not least is your own particular preference. I like a very close Off Contact, where as my partner likes a larger gap or Snap Off setting.

    The setting is adjusted in the following manner on a rotary machine:

    Secure the screens on the arms of your machine. Lower one of the screens down on to a platen. You will be looking for two things from under the screen: First, look to make sure the screen is parallel to the platen on all four corners. If it is not you must level screen to the platen. This is usually done by the use of wrenches on the screen holder assembly. Go from corner to corner till the screen is level to the platen (Note: It is assumed that all your platens are level. If they are not then level them before starting your Snap Off adjustment).

    After the screen is leveled to the platen you can now do your Snap Off adjustment. Put on the platen the item you will be printing. The item thickness is important to this adjustment. If your machine is set up for a T-shirt then when you print sweatshirts the setting will be to close. Put the item you are going to print on the platen. Look above the item and just below the screen. You are looking for a gap between the bottom of the screen (Print side) and the top of the platen. For me the gap is around a 1/16”. This adjustment nut is usually on the platen arm that the screen holder arm rests on when in the down position.

    Important Note: If you are doing more than a one color print, all the other screens must be done just like the first screen making sure that all screens are level to the platen then adjusting the Snap Off of each individual screen.

    The setting is adjusted in the following manner on a Universal System:
    A T-shirt is placed on the platen. A screen is set in the holder above the T-shirt. From behind the machine look through the adjustment opening and look for the gap. With the turning of the platen height adjuster knob raise the platen rear up till the desired Snap Off is achieved. Now, look for level. Adjust level with the platen level adjuster knob, secure platen, and the adjustment is done.

    Important note: You only have to do one screen no matter how many colors you are doing. It is a one-time adjustment.

    Printing

    So now you are ready to print. This is where you make your money. Printing is the easiest part of this business and I think it is the most fun.

    Let’s say you are doing a multi-color design. What color do you print first? There are two schools of thought on this subject. The widest used method is to print from the lightest color to darkest color: white, yellow, red, blue and finally black.

    Next, chose your weapon (squeegee, that is!). Which squeegee do you use? Squeegees come in different hardness, length and blade designs. For the beginner you will need a medium to hard, square bladed squeegee. The length of the squeegee you will need is determined by the design size. Your squeegee should be larger than the area you are printing. On a small design it should be a ½” over each side of the print and on a large design it should be 1” over each side of the print.

    RENOLIT Calendered Vinyl - Top performance for various applications

    P.A.P. (Pull, Angle, Pressure)
    P.A.P. is an acronym for the use of a squeegee when screenprinting. I will now explain it letter by letter.

    Pull: You should pull the squeegee over the screen from top to bottom. Start your pull approximately 1” above the print. Do not start in the middle. Stop pulling approximately 1” below the print.

    Angle: You will want to keep the squeegee at a 45-degree angle from start to finish. This sounds easy but it is not because of the skeleton make up of your body. When you push your hand out far in front of you and pull your arm back your wrist begins to drop. This is normal. But when your are printing, you start out at the 45 degree angle and begin to pull. If you are not paying attention your wrist begins to drop and your angle starts going down, 35 degrees, 20 degrees, 0 degrees. You want a consistent 45 degrees. What I have found that works best for me is to put one foot a little behind the other and lock my arms and rock back with each pull, lock and rock at the same time. It takes practice but you can do it.

    Pressure: This means how hard you push down with the squeegee on the screen. Which in turn pushes the screen down on the substrate. You want to exert enough pressure to feel the platen below. Over pressure will deposit too much ink and under pressure will give you a light print. Again, practice makes perfect.

    There are a few factors you need to consider in relation to the amount of ink that you will deposit on the item. How thick is the ink I am using? How much pressure did I use? What angle of the squeegee pull did I use? How fast did I pull the squeegee over the screen? All these factors add and subtract from the ink deposit on the substrate.

    When you first begin screenprinting experiment (practice) with different forms of the above-mentioned questions. Find what works for you. Understand the relationships between all of them. This will come in handy as you progress in screenprinting.

    Add ink to your screen and begin to practice to print and have some fun.

    Ink: Use and Type
    There are many types of inks for different applications. Chose the substrate, and identify what you want to achieve. Then, match the ink to these two needs. Different inks for different jobs.

    When choosing ink, check and read all information carefully. Find out the pros and cons of all inks. See how the ink is to be cured and what chemicals you need to clean up after you are done printing. Heed any precautions in the instructions. We will discuss more about ink in a later issue.

    There are two basic inks for the substrate of cloth: water-based and oil- based. The generic term for oil-based ink is plastisol. There are many manufactures of these two inks, but they all work basically the same. I will attempt to explain the differences when working with, printing with, and curing both inks.

    Water-based inks are used more in England and Europe than plastisols are. In the United States, it is just reversed in usage.

    Water-Based Inks
    Water-based inks have change drastically over the last few years. They have improved to rival plastisols for color, lasting on the items and in their overall use. Water-based inks work like dye. The strands of the fabric are dyed. They are made to penetrate the fibers of the garment. The consistency of the ink tends to be a little thinner than plastisol ink.

    Water-based ink dries (cures) by leaching the water from the ink. This leaves the pigment dried and imbedded into the fabric. The ink will dry on its own without the aid of a dryer. Many printers use a dryer for water-based inks. This increases production of garments. The ink can also be activated to aid in the drying of the inks. The largest problem you have when you print with water-based ink is that all the time the ink is in the screen, water is evaporating in the air. You must be aware of this and not let the ink dry in the screen. Most printers keep a squirt bottle next to the screens to mist the screens to add water to the ink to keep it from drying.

    In most cases, when you start a print job you finish it completely to keep from having problems with ink drying in the screens.

    Plastisol Inks
    Plastisol ink is an oil-based. The first plastisol inks were made from the same substance that forms the rubbery covers on your tools. Plastisol ink does not dye the fibers of a garment; rather, it is at its best when applied to the surface of the garment. Produced from oil, it will never dry, it cures. It cures with heat. The approximate heat required to cure it is 330 degrees F (166 degrees C.). If it does not reach the proper temperature, through the entire body of the ink, it will not cure and will wash out. Temperature becomes critical with plastisol. This is its biggest problem for the printer. It must reach the proper temperature.

    The advantage of the use of plastisol is that it never dries (cures) in the screen. You can leave it an hour, day, week or months and it will never dry. The colors tend to be very bright when used. It is very easy to work with. When you are done with your job just scrape up the extra ink and return it to the container to be used again.

    Dryers
    If you are printing with plastisol inks or activated water-based ink and you want production, you will need a dryer. There is a myth about dryers. When you start looking for a dryer the salesperson wants you to believe that you need a belt dryer. In many cases this is not true. Belt dryers are good for one thing. That one thing is production. The truth of the matter is that a dryer can be anything that will bring your ink over 330 degrees F. (166 degrees C.).

    It can be a belt dryer or an area dryer (flash dryer).

    When I started I used the oven in my house. These will all work. I read an article that estimated that flash dryers cure about 80% of all the shirts that are printed in the United States.

    In the Universal All-In-One system we use a flash dryer along with an all aluminum platen to give it even, top and bottom heating and curing. Many different and varied systems work in the curing of garments. You decide what works for your screenprinting company.

    In our next segment, Screenprinting 101, Part IV, we will finish basic screenprinting. This final article will include testing of garments, clean up, the use of environmentally safe products, pricing, other inks and applications and more.

    Company
    Home
    Advertising Info
    About Us
    Contact Us
    Privacy Policy
    Site Map
    Resources
    Industry Resources
    Associations
    Retail Sign Shops
    Books
    Product Showcase
    Event Calendar
    Tips & Tricks
    Message Boards
    Classifieds
    Buyer's Guide Listings
    Search
    Add My Company
    Edit My Company

     

    © Copyright 1999-2017, All Rights Reserved.