Managing Mesh, Ink Film, and Screen Life
Davis explains why you should resist the temptation to overload your mesh inventory and discusses ways you can make the most of what you already have.
August 8, 2006
There are two types of garment screen printers when it comes to mesh: those who keep a wide variety of mesh counts on hand and those who get by with three or four mesh counts for the majority of their work. Each approach has its benefits and trade offs.
Printers who have lots of mesh choices benefit from the wide selection, but they also may suffer from additional overhead costs associated with holding excessive inventories. Smaller shops typically make a more conservative assortment of mesh counts work for most of what they do and usually only order specialty meshes on an as-needed basis. They benefit by not having to store lots of mesh, but the lack of a broad mesh selection may slow down turnaround time on a job or make the job impossible to handle. The trick here is to find the happy medium between the two.
Identifying your mesh needs
Printers who are just starting out need to determine which meshes will suit their primary needs. Novice printers who don't already have a working knowledge of the relationship between mesh counts and ink-film thickness will have trouble at first. Printers must consider the types of jobs that account for a majority of the shop's business. These jobs dictate which mesh must be kept in stock.
Identifying the right mesh types for printing on light and dark garments is essential. You'll need mesh that is capable of properly covering a dark substrate, underbase, or high-opacity print, as well as finer mesh counts for light-colored garments and overprints. You'll also have to consider mesh selection in terms of minimizing your ink-film thickness. Careful control of ink film reduces the print's hand and increases ink mileage.
A large facility with automatic presses may stock monofilament polyester meshes in 86, 125, 140, 160, 180, 230, 255, 305, and 420 threads/in., as well as one or two meshes for glitter. Such an inventory really is overkill for all but the biggest garment printers, and that wide array of materials must be managed carefully. Garment printers who use manual presses can get by with the following mesh counts:
• 86 threads/in. for metallics and some special-effect inks
• 125 threads/in. for underbases and high-opacity prints
• 230 threads/in. for overprints and light-colored garments
• 305 threads/in. for fine halftones and photographic reproduction
I currently use these four mesh counts for virtually all of my printing, and I handle 90% of that with 125- and 230-thread/in. mesh. Needless to say, my mesh inventory is minimal. Identifying your primary mesh needs enables you to narrow your selection to those you actually bring to press and prevents the need to keep yards of expensive mesh you most likely will not use.
Controlling ink film
I keep a few 200-thread/in. screens on hand and most often use them for controlling wet-on-wet overprints for light or medium-shaded garments. I print all the colors of a multicolor graphic through 230-thread/in. mesh, which allows for good coverage and maintaining a soft hand. I then use the 200-thread/in. mesh for trapping black outlines. The reason is that the 200-thread/in. mesh will deposit an ink film that will easily cover the ink films previously printed through the 230-thread/in. mesh, leaving a crisp edge without adversely affecting the hand of the print.
Simple tricks like these will make your life easier when you use manual screen-printing equipment. You can also use the 200- or 230-thread/in. mesh counts for your highlight whites when printing on dark garments, where you still need a bump plate for white ink films or to back up underbase prints. Even though manual machines can't really reproduce graphics with the same consistency as automatic screen presses, the right manipulation of mesh counts and inks will help you print at nearly the same quality.
The next part of controlling the variety of mesh you stock is ensuring that you get the most use possible out of every screen you bring to press. You have two big considerations to keep in mind. The first is knowing how to control your screen tension; the second is how to properly handle those screens.
I use retensionable screens most of the time because they help me produce the best print possible with the softest hand. The benefits of retensionable screens are well known to most, although very few of those who use manual screen-printing equipment use them. The greatest advantage for the manual printer is the degree of difficulty that the retensionable screens remove from the manual screen-printing process. High-tension screens allow for lower off-contact and less squeegee pressure to properly deposit the ink film onto the substrates. This equates to less effort required during the printing process and, consequently, greater productivity.
Increased screen longevity is another big benefit of using highly tensioned mesh on a retensionable frame. Many garment-printing facilities that use manual equipment stock their storage racks full of tubular-aluminum or wooden frames. These frames may have their uses in manual screen printing, but the simple truth is that the tension of screens stretched on these types of frames will eventually drop to the point where printing quality will suffer. The effort required to properly print with these screens will not be worth the initial savings, and you'll waste valuable time removing the mesh and either restretching it or replacing the mesh altogether. Retensionable frames allow you to maintain your initial (or higher) screen tension and greatly extend the life of the mesh.
Proper handling is, perhaps, the greatest challenge associated with retensionable frames for screen printing. High-tension screens will rip as easily—if not more so—than low-tension screens, so printers must handle high-tension screens with an additional degree of care. You may need to provide your employees with additional training to make sure they understand the benefits of using retensionables, the appropriate ways to handle high-tension screens, and the techniques that increase the longevity of the tensioned screens.
Having a generous assortment of mesh materials in inventory may be a luxury to some shops and a necessity in others, but many facilities are simply not equipped to fully take advantage of such a broad selection. Instead of worrying about stocking every mesh known to man, concentrate instead on keeping and managing the mesh types that you need the most. Doing so will help minimize your overhead and maximize your productivity.
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