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Choosing the right frame and mesh is critical to achieving quality prints. This overview looks at different frame types, mesh parameters and performance criteria, screen-preparation tips, and recommendations for ensuring long-lasting screens.
• Whatever the stencil system, the screen must be cleaned and degreased before each use. Failure to do a proper degrease on the mesh can result in the stencil delaminating or breaking down during the print run. Failure to clean the screen before re-use leaves ghost images and blockages that will haunt your next stencil and cause problems in future prints.
• When not being used for printing, screens should be stored to avoid being accidentally ripped or damaged. During printing, avoid contact with knives or other sharp objects.
• If screens are cared for properly, they can be used over and over, sometimes for years and thousands of impressions, before requiring replacement.
• The two main reasons for replacement are blocked openings that will not come clean and ripping or delamination of the mesh.
• It’s always a good idea to mark the mesh count and age of the screen on the side of the frame, and institute a rotation and replacement system to ensure that screens are always in good shape for printing.
Selecting the right frame and mesh and preparing your screens properly will put you on the path to quality printing more effectively than any other procedure you can perform in the screen-printing workflow. So give your screenmaking process the time and attention it deserves. n
Mesh Recommendations by Application
APPLICATION
MESH COUNT (threads/in.)
Graphics printing
Line artwork 230 –305
Halftone screens up to 70 lines/in. 305–380
Halftone screens from 70-133 lines/in. 380 –420
Objects (plastics, etc.)
Opaque areas 255–305
Halftone and fine lines 305–420
Garment printing
Glitter 25–60
Flock adhesive 45–125
Puff-up colors 55–125
Overprint 80 –110
Pigment ink printing,areas/lines 110 –175
Plastisol transfer 125–305
Universal fabric 125
Plastisol direct 125–305
Pigment inks, half-tone 155–255
Sublimation transfer 195–305
Textiles, flat films
Heavy décor fabrics (terry cloth, denim) 45–123
Smooth, dense fabrics (table cloths, curtains) 110–155
Light, porous material 195–305
Ceramics
Glaze printing, coarse, embossed effect 15–55
Glaze printing, medium to fine 55–155
In and under-glaze (direct printing) 110–255
Decals
Areas/lines 195–380
Fine lines/half-tone 255–420
Gold and luster inks 305–420
Glass
Automotive glass
Black surrounds for rear/side windows 125–195
Antennas 195–255
Silver paste (defroster) 195–255
Architectural glass
Windows, doors 55–195
Mirrors 195–305
Cosmetic bottles
Inks 195–305
Precious metals 305–380
Beverage
Bottles, glasses 125–305
Household
Ovens, etc. (masks) 110 –175
Ovens, etc. (lines and half-tones) 195–255
Lampshades, furniture 125–255
Advertising
Shop signs 110 –195
Printed circuit boards
Overlay solder mask 30 –45
Photosensitive solder mask 60 –175
Membrane keypads and overlays
Insulation lacquer 90 –175
Silver conductive paste 125–175
Adhesive 125–195
Transparent windows 305
Andy MacDougall is a screen-printing trainer and consultant based on Vancouver Island in Canada and a member of the Academy of Screen Printing Technology. If you have production problems you’d like to see him address in “Shop Talk,” e-mail your comments and questions to andy@squeegeeville.com.
Editor’s note: This article is was adapted from a section of Andy MacDougall’s new book, Screen Printing Today: The Basics, published by ST Media Group Int’l. The book will be available beginning in mid-November 2008 through ST’s book department and can be ordered online at http://bookstore.stmediagroup.com.
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