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.

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Posted: Mon - June 6, 2005 at 02:34 PM