Righting the Wrongs

TYPICALLY, WE START with a “To Do” list when training new screen printers. But sometimes it’s best to recommend a “Don’t Do” list to save printers from making these errors. To help me identify the things screen printers should not do, I reached out to six veteran screen printers to get their suggested top errors printers can make. During discussions with these pros, we had some good laughs with suggestions like, “Don’t heat up your food in the dryer,” and “Don’t call it paint.” In the end, we came up with a solid 10 “Don’t Do’s” for screen printers. I know we have all made one or more of these mistakes, so it’s just as important to know what doesn’t work as it is to know what does work.

Peter Jr. with New Era Apparel suggests the first “Don’t Do.”
1. Stop matching other printers’ price sheets when you have no idea what their margins are. Also, stop pricing the end-user jobs with screens and set-up charges. McDonald’s doesn’t break down the lettuce and cheese on a quarter pounder!

I agree with Peter that one of the biggest mistakes a shop can make is simply matching your competitors’ pricing without determining the actual costs of your goods and services. It’s important to be within the market price range, but there is no need to match the competitor’s price just to get the order.

Next, Rick Roth, owner of Mirror Image, offers squeegee advice.
2. Don’t be dull and don’t be cheap! Replace your squeegee rubber. If you haven’t tried triple durometer 60/90/60 blades, this would be a good time to try them. Years ago, I worked with a large screen-printing company to improve their print quality and replaced all the squeegee blades. It resulted in an improvement in the print quality that was immediately noticed. The 60/90/60 squeegee allows the soft 60-durometer edge to shear the ink onto the surface of the garment, while the 90-durometer center reduces blade deflection during the print stroke. This helps maintain the proper squeegee angle.

When it comes to ink deposits on screens, John Magee with Avient Specialty Inks chimes in.
3. Don’t coat screens one handed and make sure you understand the importance of stencil thickness as it relates to the quality of the print. EOM (or emulsion over mesh) should be 20% EOM on the contact side of the screen to create a gasket for the ink to pass through. A thick stencil provides a thick ink deposit, improving opacity and print durability.

My suggestion for the larger automatic shops is to get an automatic screen-coating machine to control the EOM on all screens to make all the prints more consistent. For small-to-midsized shops, screen holders are available that allow the screen to be clamped in place. This lets the screen to be coated using two hands and makes the stencil thickness more consistent from the top of the screen to the bottom.

Here’s tips to clean your screens from Alan Howe of Easiway Systems.
4. When you’re finished printing with plastisol, do not use hot solvents like screen opener, xylene, or lacquer thinner to clean your screens. These harsh solvents can cause stencils to lock up and make it impossible to reclaim the stencil. The use of these hot solvents also will cause excess staining on the mesh from the pigments in the plastisol. This will cost you more time and money by needing to use additional chemicals and haze removers to get the stains out of the mesh.

Keep your eye on exposure with this advice from Rick Davis, a retired 40-year industry veteran.
5. Don’t guess on your screen exposure times. There is no guessing in screen printing! Dial in your exposure times using a good 21-step exposure calculator.

Mark Suhadolnik, GSG Applications Manager, gives dryer and flashing technique advice.
6. When venting your conveyor dryer, avoid 90° bends in the dryer duct. Air does not turn corners at a 90° elbow in the vent and will cause vapor and fumes to build up in the dryer. If a 90° bend is used in your exhaust duct, then a booster fan may be needed at the exit of the duct.

Don’t overheat when flashing.
7. Excessive heat can cause damage to the fabric or cause distortion of the print. This is a common problem that many screen printers experience when printing with plastisol. Overheating the underbase when printing with plastisol also will cause the ink to fully cure and now any inks printed on top will not adhere to the fully cured under base. Also, don’t rush the flash curing process. It’s not about speed — it’s about achieving the right temperature and consistency.

From Yours Truly, I offer this advice on dryer consistency, color-matching, and varying garment decoration methods.
8. Don’t overload the dryer. Placing too many garments in the dryer can result in uneven and inconsistent print quality. I always recommend that it is important to profile your dryer periodically to be sure it is reaching the correct substrate temperature and the best tool to use to check your dryer substrate temperature is with an Atkins temperature probe. To use the donut probe correctly, print on a scrap T-shirt and embed the crosshair wires on the donut ring directly into the wet ink. Run the garment and donut probe through the dryer to monitor and record the oven temperatures as the T-shirt goes through the chamber. Usually, the cure temperature is not reached until the garment is three quarters of the way through the oven chamber.

Don’t cut corners when investing in an ink color-matching system.
9. Get a system that has an online PMS formulation guide to provide the percentages of base and color in grams that are needed to formulate the PMS color you are matching. And example is the IMS 3.0 color-matching system from Avient, which has thousands of online PMS formulas that provide the mixing ratios needed to match the PMS color. In addition, the IMS 3.0 system has a recycle feature that allows you to mix other colors from the PMS color that is left over.

Don’t rely on just one garment decoration method now that options exist with DTG and DTF technologies.
10. Many decorators will look at the size of the job at hand and, if the design is eight colors or more, the option might be to go with DTF transfers. Or, if it’s a low-volume job, it makes sense to go with DTG printing instead of exposing and washing out eight screens and setting up the press for less than 50 garments.

Whether you are training new employees or starting up a shop from scratch, the above-mentioned “Don’t Do” list will help you avoid some costly mistakes. Screen printing textiles is all about finding a process that works for your shop and training employees to repeat the process. That’s the key to any shop’s success!

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