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Screen Printing Technique
NEHOC's easy to use equipment and the provision of professional squeegees and inks have changed two basic elements of screen printing.
It’s NOT the pressure applied to the squeegee that pushes the ink
through the screen and onto the item below . . . it’s actually the sharp edge of
the squeegee blade that pulls a fine layer of ink through the screen mesh, which
is designed to regulate the amount of ink that passes. So excess pressure just
blurs your design and reduces quality.
If you have never screen printed before then you will normally receive a better print than a person who has using old techniques, as they must remove old habits of excessive pressure which was required using the outdated equipment and inks.
You must use pressure on the squeegee to keep even pressure along that blade so one side does not print more than the other, however you can screen print with 2 fingers holding the squeegee blade - let the squeegee & ink do the work for you.
Basic Screen Printing Technique
3. With sufficient ink on the blade,
about 7-10mm thick, place the squeegee onto the edge of the screen, then lower
the blade and rock forward & back 3 times to transfer this ink onto the screen
and then bring the angle back up ready to print
4. Pull the squeegee across the screen at an angle of approx. 70 degrees from one side to the other, when complete raise the squeegee angle back to vertical to ‘pick up’ the ink and remove from the squeegee from the screen
A hinge motion is used to avoid smudging/ blurring the print [hold the frame on one side]
If the print is too light you can lower the frame and print again as the hinge effect holds it in place
Points to Note
Your squeegee should be at approx. 70 degrees and move freely across the screen
If too much ink is flowing off the outside edges and the print is blurred or heavy, then you are pressing too hard
Once you commence printing you will quickly determine the correct level of pressure and squeegee angle that suits - the prints will tell you what you are doing wrong
|Prints too dark, blurred, smudged or not a clear image = pressure too great and squeegee angle too low
Prints too light, not a clear image = pressure too light, squeegee angle too high or not enough ink on the squeegee
Heat Setting Fabric Inks
Fabric screen printing ink requires heat setting in order to cure/set the ink to the fabric. The following is a guide to the heat setting process and explains why prints should be heat set for 2 minutes to ensure permanent bonding.
150F [66°C] Water begins to leave the ink
200F [94°C] Binder reaches lowest viscosity and maximum surface contact is made with the fabric
220F [105°C] Water begins to leave the ink rapidly
270F [133°C] Fifty percent of the water is gone and the binder and pigment start to cure
300F [150°C] Most of the water is gone and the binder-pigment combination is partially cured
300F [150°C] [for 30 seconds to a minute] Binder and pigment is cured
[The above should be used as a guide only, and may vary slightly between ink types. Times printed on sides of containers are for wet prints. Curing of dry prints still takes at least 2 minutes as ink has to get to temperature first.]
NEHOC Aqua Inks [plastic/ metals] and Air Cure Ink DO NOT require heat setting - each ink will air dry [can be force dried with a hair drier] and will set in due course - see ink for details.
Cleaning & Storing Screens
Always use water soluble inks with ScreenMaster, this makes cleaning easy as you can always clean under cold running water. The ink will quickly break down leaving you with a perfectly clean screen.
Always store RISO ScreenMaster screens away from any heat source [heaters, lights, etc.], in a cool/ dry place.