I’ve been evaluating prints for a while now, as a result of working for several high-volume operations, as a sales rep for M&R and for the past five years, in my own manual shop, Sound and Fury Print Shop in Chicago. As you gain experience, you develop your own procedures and know what to look for.
Here, I am going to talk about a checklist you can use as a starting point as you develop your own system for ensuing only top quality comes out of your shop
You want to check that the thickness is what is desired for the effect you want to create. For example, if I'm doing a halftone underbase, I want to make sure my deposit is matching my halftone. If it’s a 50% halftone, I want 50% deposit.
If I'm trying to have sufficient coverage for larger fibers, I need a thicker stack of ink. If I’m printing fine lines, I need a thinner layer. And of course, I’m always evaluating that the colors are holding true to the PMS swatch card.
Squeegee pressure is important when adjusting your ink deposit. You do not want to smash ink down so hard it sinks into the substrate. Too much squeegee pressure also can cause dot gain. This is where instead of a halftone dot holding its shape, it spread out or bleeds outside its prescribed parameters.
I like to check a shirt after it has come off the dryer. Turn it inside out. If you see ink has bled through to the inside, you know to ease up on the pressure.
If I'm applying too much pressure, which is common, you might be thinking "Oh, this one screen won't clear unless we increase the pressure." Well, if I have to up the pressure to clear the screen to the point where I'm printing through the shirt, then the screen is the issue, not the pressure. I often will check for this more than once during a run.
This is a challenge you will see more often on thinner shirts, especially during the summer when you are printing on lighter and white garments. A thinner, water-based ink more easily prints straight through the shirt.
Discharge is another common cause of this happening. If the operator is using the same pressure as he used with a plastisol ink, it’s likely to bleed through.
The one exception is if you are trying to do a reverse print. A reverse print is where you use a water-base ink and deliberately print through the shirt giving the design a worn, retro faded look. In this case, you are printing the shirt inside out.
Reverse prints were really popular in the ’80s. I still see examples of reverse prints in surf shops. Sometimes you can use a texture, which mimics the look. But it’s not a look currently trending.
Does the client want a heavy, bulletproof feel as is popular with sports and athletic shirts? Or is it a lightweight women’s garment where you are striving for the softest hand possible? Make sure you know what your customers’ expectations are and deliver on them.
You’ve also got to know what the customer’s expectations are when you evaluate the finish. Do they want a matte, glossy or something in-between? You might get every other detail of the print perfect and have the shirt rejected because it’s too shiny.
I always do a cure test and I recommend everyone check their dryer temps multiple times a day. At the very least, I use a dryer thermometer to check my curing temp on the garments during a run.
During a press proof, I check to make sure the inks are going to hit the temperature from the ink manufacturer's recommendations for that substrate.
I also do a stretch test. This is a procedure that is oftentimes done wrong. I've seen a lot of people grab the print and pull it apart as far as they can. It's going to crack if you do that.
A stretch test should be more like the equivalent of an extra-large guy trying to put a medium shirt on. In that situation, the shirt is going to get stretched out, but the print should still look okay. I pull on the shirt enough to match the approximate equivalent of that example.
If it's a garment I'm concerned about, I might do a crock test, or at the very least, I'll get some really hot water and rub a white shirt against the ink and see if anything comes off on the white shirt.
If it's a garment I'm not familiar with, I might order an extra piece, and do a similar print I have running a day or two before that job. I print it on that garment, take it home, and launder it once or twice to make sure it's holding up.
The most foolproof way to test for a proper cure is a crock test. This is where you use chemicals and/or hot water to simulate how the shirt will respond to multiple washings. The most basic crock test technique is to boil water on a hot stove, put the shirt in the pot, and when you take it out, abrade it with a toothbrush or something similar. This simulates basic wear and tear.
It’s more common for printers to do a temperature check while it’s going through the dryer and then once it’s cooled, doing the stretch test mentioned above. At my shop, we heat press every print. This also ensures the shirt is properly cured.
When we use the heat press, it also helps with the mat down, the longevity, and in determining what the finish looks like, matte or gloss or anything in-between. If a shirt is not completely cured, you have to run it through the dryer again, or you can heat press it.
Anytime a customer comes back with a shirt saying it was washed and the print cracked, if it has not already been distributed, you can have the client bring the order back and heat press them. That can save the day.
If you want to read my blog on how and why I heat press all my shirts, go to https://www.boardofdecorators.com/cashing-heat-press-advantage.
If you're running on an automatic, ideally, you’re got a catcher at the end of the dryer who has the authority to stop the press. That operator has an approved strike-off print that he is using to compare to, and it needs to match perfectly.
This gets trickier when you are running a press by yourself. I don’t recommend running an auto by yourself. But even it’s a manual press, I recommend not printing more than a dozen or two shirts before going to the box at the end of the dryer and checking the prints.
In my experience, it's better to go a little slower and do it right, than do it faster and having to replace the whole order later.
I hope you will find this checklist useful when evaluating your own prints. In the third blog in this series, I will talk how the evaluation process and documentation can help you establish your shop’s quality control standards and maintain them.
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