Supply Considerations for Small Shops
Small shops can get into big trouble when they neglect to test their supplies and document procedures. Use this overview to avoid potential pitfalls.
The decision for small garment-printing shops and start-up operations as to which mesh, inks, squeegees, and other tools and products to use is one they must make for each job that comes in. No one product performs the same way from facility to facility, which only adds to the confusion.
The manufacturers on whom we rely for our supplies typically give us sets of operating parameters to use with each product; however, these guidelines are starting points. Ink manufacturers, for example, describe which meshes and squeegees to use with their different formulations, but the unfortunate truth is that realizing optimum performance from the supplies your shop selects is most often a result of product-to-product troubleshooting.
The screen is the first place to look when ironing out the great many variables that cause the differences in product performance from shop to shop and from job to job in your own plant. Screen tension is an important consideration; however, I won’t start in on the benefits of high tension screens—save for a reminder that the higher the tension of the screen, the faster and easier the printing process becomes. This effect is partially due to the fact that high-tension screens typically have a greater percentage of open area with a given mesh than a screen of lower tension with the same mesh count. That being said, let’s take a look at the influence of mesh on ink use, the impact of ink properties on printed garments, and the realities of squeegee selection for smaller printing operations.
Mesh selection and ink behavior
Although the ink manufacturers cited as an example above conduct numerous tests to develop recommendations from which you can work, you are ultimately responsible for determining which mesh count works best for any given ink in your shop. The objective of the ink companies is to move as much ink as possible. Given this fact, you need to build on their baseline references by conducting your own in-house testing.
Here’s an example. I once came across a crystalline-type product that came with instructions to print the product through a mesh no finer than 86 threads/in. After examining the product, I decided to try printing it through a 110-thread/in. mesh that, in my shop, worked great with one stroke. The particles were small enough to pass through the 110-thread/in. mesh and produce the desired result while printing half the ink-film thickness that the manufacturer recommended. The effective use of crystallines, metallics glitters, and many other special-effect inks really is a simple matter of determining the mesh count through which the particles in the ink will pass with the greatest ease.
High-opacity inks, such as bleed-resistant whites, offer an entirely different set of parameters to consider: printability, flashing characteristics, curing parameters, and cured opacity. Working with these formulations can be a tough proposition for smaller shops, especially those that do not properly test the white inks that they use. In most cases, a lack of testing for best practices when using these inks results in excessively thick ink films that retain a poor hand, a loss of detail, and poor cure rates due to the excessive thickness of the printed design. I find this scenario to be more prevalent with printers who attempt to print on 100%-polyester specialty fabrics. They lay down excessively thick ink films in hopes of avoiding dye migration and sublimation, both of which occur more and more frequently thanks to the cheaper polyester dyes that are produced in Asian countries.
Smaller shops have to keep in mind that their (typically) smaller dryers are only capable of curing ink films up to a certain thickness. Past that point, you won’t be able to cure the entire ink film. The result is not only potential bleeding on polyester fabrics, but also poor washability on any fabric. Therefore, you need to determine your proper printing, flashing, and curing parameters for the mesh you use in your shop and standardize that particular mesh count for those applications. I chose in my facility to minimize my mesh counts and mesh inventory and primarily only use 110-, 155-, 200- and 305-thread/in. mesh counts. I can address virtually any application that most customers desire.
Squeegee selection is a variable in the garment-screen-printing process to which few printers give enough thought (for more details about squeegees, consult Tips for Squeegee Selection on p. 31 of this edition of Screen Printing). The truth is that many reordered multicolor prints suffer from fluctuations in quality because shops fail to document the squeegee-related parameters they use during a given production run. Keeping thorough, accurate records in this area enhances quality and productivity.
Here again, as with my mesh counts, I prefer to minimize my squeegee selection as much as possible in order to reduce the number of potential variables within my own facility. This is even more prevalent for smaller shops that have a few employees, where a different printer might handle a multicolor order without knowing the operating parameters followed during the initial production run. You should always document squeegee parameters, regardless of whether you use two or six different squeegee durometers in your facility.
While I’m on the subject, the different squeegee durometers available will baffle a rookie coming into the business and can confuse even seasoned printers who are starting their own shops. As a basic overview, you can select from single-durometer squeegees, such as 60, 70, 80, 90; dual-durometer squeegees—60/90 and 70/90, for example—and triple-durometer squeegees in configurations such as 60/90/60 and 70/90/70.
My preference from the standpoint of quality is the triple-durometer squeegee, but most small shops typically opt to use the standard, single-durometer squeegees in the name of cost, as they are the cheapest of those offered. I believe that you generally need only two different squeegee durometers to execute 90% percent of your applications without excessive effort.
I would suggest a 70-durometer squeegee for printing heavier ink films on darker shades and an 80-durometer for thinner ink-film thicknesses applied to lighter background colors. Again, even if you only have two different squeegee durometers in use at your shop, that does not relieve you of the responsibility to document which squeegees you used for any one particular job. You also need to make careful note of other parameters related to your squeegees. They include squeegee pressure, speed, angle, and radial edge (if any).
Small shops and newcomers to garment screen printing are often best served by keeping things as simple as possible. Still, even the simplest choices can become complicated decisions when you don’t document your actions. Keepings records of your mesh counts, squeegee durometers, and other information related to the supplies you use each day will help you ensure quality from order to reorder.
Rick Davis is the president of Synergy Screen Printing in Orlando, FL. A 27-year veteran of the textile-printing industry, Davis is a member of the Academy of Screen Printing Technology and has a background that spans production management, artwork engineering, application testing, and industry consulting. He is a frequent contributor to trade publications and a speaker at industry trade events.