Impressions - October/November 2013 - (Page 62)

talking SHOP Screen Printing Technique Controlling Variables, Part 3 In this continuing series, we explore the ink transfer/printing process from the screen to the fabric surface. By Rick Davis, Contributing Writer i n part one of this series, I wrote about the variables involved with the prepress process that require the greatest degree of control. In part two, I reviewed the required screen variables. In this issue, let’s consider the variables of the ink transfer/printing process found in transferring ink from the screen to the fabric surface. We also will review the variables surrounding the inks and squeegees with regard to the printing process. Screen printers can only obtain knowledge of plastisol ink with time, experience and repetition. The actual determining factors of a quality ink lie in the hands of the printers themselves. Ink that prints perfectly for one printer may never work for the printer located down the street. In many situations, the conditions in which the ink is used determine its performance. Although the ink’s quality is key in numerous factors, its performance will only be as good as the conditions under which it is used. There are a number of key 62 Impressions | October/November 2013 factors that screen printers look for in the plastisols they use. Viscosity/Printability: The most important aspect of a plastisol screen printing ink for a textile screen printer is its ease of use. This is referred to as viscosity or printability. Most plastisols have a creamy viscosity like that of peanut butter. Typically, they are thicker in the can than on the screen. This is to say that most plastisols are thixotropic, which means they will loosen up or decrease in viscosity. This happens once the ink is sheared either by being stirred in the bucket or being loosened by moving it in the screen. The latter can be done either with the squeegee on a manual press or the squeegee and ﬂood bar on an automatic machine. Many screen printers misinterpret ink as being too thick, when just a little mixing will readily break down the false body that has set up, rendering it perfect for printing. Opacity: Opacity refers to the ink’s The most common issue that textile screen printers using plastisols encounter today is the under- or over-curing of the printed ink ﬁlm. The most important thing to realize is that the entire ink ﬁlm thickness must reach 320˚F for the ink to perform to desired expectations. ability to properly cover the fabric and there are a number of factors that will determine this characteristic. There are ink components that will determine its base opacity in conjunction with its viscosity. This includes the percentage of pigment built into the formula, the quality of the pigment used, and the type and quality of ﬁllers used in the formula. Proper Curing: The most common issue that textile screen printers using plastisols encounter today is the under- or over-curing (re-melting) of the printed ink ﬁlm. The most important thing novice printers must realize is that the entire ink ﬁlm thickness must reach 320˚F for the ink to perform to desired expectations. If this doesn’t happen, the result is poor bleed resistance on synthetic fabrics, poor impressionsmag.com http://www.impressionsmag.com

Table of Contents for the Digital Edition of Impressions - October/November 2013

Impressions - October/November 2013
Contents
First Impressions
From the Show Director
FYI
Product Gallery
ISS Conferences
Allover Printing: It's All Over America
The Digital Direction
Peak Performance
Tracking Trends is Key to Business Survival
Shop Spotlight
Shop Spotlight
Embroidery Design & Digitizing
Embroidery Technique
Screen Printing Production
Screen Printing Technique
Online Directory
Digital Decorating
Classifieds
Ad Index

Impressions - October/November 2013