Impressions - February 2011 - (Page 45)

HANDS ON >> By James Ortolani, SCREEN PRINTING >> Contributing Writer HANDS ON HANDS ON For Screen Printers Only SCREEN PRINTING HANDS ON TECH TIPS HANDS ON When to Upgrade to Retensionable Screens Investing in a frame upgrade allows you to maintain consistency on several production variables. No one ever said you can’t print awardwinning designs without retensionable screens, but adding them to your shop greatly will increase your ability to control the variables in the production process. Anyone can print one great T-shirt design, but try to print 1,000 shirts that must each look exactly the same. You need to maintain registration and ink deposit consistency throughout the entire print run, and that’s where retensionable frames really give your shop an edge. The temptation to buy stretch-and-glue frames always will be present because they are a low-priced option and are press-ready when you get them. But that doesn’t mean stretch-and-glue frames are necessarily the best choice for your shop. Whether screen mesh is glued to a frame or locked in place with locking strips on a retensionable frame, both systems will lose tension the ﬁrst time the screen is used to print a job. With the stretch-and-glue frame, you accept the fact that the mesh will relax. But with a retensionable frame, you simply tighten the mesh and get all the beneﬁts associated with higher-tension printing. These include better image registration and ink deposit control; less dot gain, ink buildup and ink usage; better “snap off;” and longer-lasting mesh. There also is a “green” factor associated with using retensionable screen frames. These eco-friendly beneﬁts include the fact that no toxic glues are used to attach the mesh to the frame, and the mesh is recycled and used many years longer than mesh used with a stretch-and-glue frame. Basically, there are two types of retensionable frames available: roller and square. The choice is yours and both systems offer higher-tensioned mesh. Regardless of which system you choose, the frame in question must easily be retensioned to add value to your operation. I see too many shops printing with retensionable frames, but the employees fail to retension these frames on a consistent basis. impressionsmag.com TECH TIPS HANDS ON >> If retensionable screens are never retensioned after the initial stretch, you haven’t gained anything except a more expensive frame. Break out the tool kit and cross-train several employees in the area of stretching retensionable frames. I recommend marking a date on the calendar and sticking to that date to inspect and retension the frames that need attention. With a good screen maintenance schedule in place, the process of retensioning your frames only will take one hour a week, which is time well spent. Retensionable frames allow for higher tension printing, which results in better image registration, better ink deposit control, less dot gain, less ink buildup, less ink usage, better “snap-off” and longer-lasting mesh. Photo courtesy of Hix Corp., Pittsburg, Kan. FABRIC & TENSION BENEFITS Monoﬁlament Polyester is the main screen fabric that is used in today’s commercial screen printing industry. Each individual strand is extruded polyester held to very tight tolerances in terms of controlling the thread diameter, which is measured in microns and has a dramatic effect on the print quality due to its effect on the percentage of open area at the mesh grid cross section. In simple terms, a thicker thread will block more ink in the mesh cross section than a thinner thread of the same mesh count. Warp and weft are terms you need to know when working with screen mesh. Warp is the length direction of the screen fabric as it comes off the bolt (roll of mesh) and weft is the left-to-right weave in between the selvedges (the self-ﬁnished edges of the fabric). Historically, threads in the warp direction could be taken to a higher tension level because the long length of the warp thread allows for better elongation. But with today’s low-elongation mesh and improved weaving technology, the warp and weft threads have become more equalized. Image registration is the main benefactor from using retensionable screens. High-tension screens reduce the mesh from “rippling” under the force of the squeegee and, as a result, the image on the mesh does not move from front to back Retensionable frames are more ecofriendly than stretch-and-glue frames because the screen fabric is attached with plastic locking strips, meaning no toxic glue is used. Also, the mesh is recycled and can be used for many years longer than the mesh used with a stretch-and-glue frame. Photo courtesy of Hix Corp., Pittsburg, Kan. The mesh on this square retensionable frame is re-tightened using a stretching tool. This should be done on a consistent basis, so it is important to have a good screen-maintenance schedule in place with several employees cross-trained on the retensioning process. Photo courtesy of Hix Corp., Pittsburg, Kan. February 2011 << Impressions 45 http://www.impressionsmag.com

Table of Contents for the Digital Edition of Impressions - February 2011

Impressions - February 2011
Contents
First Impressions
From the Show Director
FYI
The Embroidery Machine Evolution
Versatile Wearables Boost Profits
Behind the Big Top
Production
Graphics & Design
For Screen Printers Only
Tech Tips
Setting Up Volume Digital Printing Production
Online Directory
Business to Business
Classifieds
Ad Index

Impressions - February 2011