High Drying Temperatures Cause Permanent Tension Loss
Fairfax, Virginia ˜ Recent Screen Printing
Technical Foundation research, shows screen tension loss that occurs with higher
drying temperatures is permanent, and further mysterious dips follow stencil
washout, reclamation and degreasing.
In 2002, the Screen Printing Technical Foundation
confirmed that higher drying temperatures cause a reduction in screen tension.
The 2005 experiment mimicked the 2002 SPTF Heat vs. Tension project with two
additional sets of screens and extended the testing to include printing each
screen with 250 impressions.
"Our goal
was to track the screens farther in the process to see if stabilization occurred
differently based on temperature," said Dawn Hohl, Technical Manager, SPTF,
noting three conclusions:
* Higher drying
temperatures result in permanent tension
loss.
* Mysterious tension dips were again seen
on measurements taken on wet screens. The hygroscopic expansion of polyester
mesh may explain these changes.
* Screen
tension remained virtually unchanged before, during and after printing on all
meshes.
"Recommendations based on this
study are to keep drying temperatures as standard as possible to ensure screen
to screen tension consistency," Hohl
said.
SPTF's research report, "Effects of
Drying Temperature on Screen Tension Part 2" due out in July, includes possible
explanations for the permanent tension loss as well as practical guidelines for
quickly and effectively drying screens. SGIA members will be able to download it
from SGIA.org at that time.
SGIA ˜
Supporting the Leaders of the Digital & Screen Printing
Community
"Specialty imaging" comprises digital
imaging, screen printing and the many other imaging technologies SGIA members
use, including those they'll tap in the future. These are the imaging processes
and technologies employed to create new products and to enhance existing
products including point-of-purchase displays, signs, advertisements, garments,
containers, and vehicles. To make the most of your specialty imaging business,
take full advantage of the information on SGIA.org, and experience the specialty
graphic imaging industry first-hand at SGIA'05 (September 28ˆOctober 1, New
Orleans, Louisiana).
Posted: Mon - June 6, 2005 at 02:34 PM