Today we are going to look at the biggest problem facing shops that screen-print apparel. At least from my perspective anyway.
My guess is that this problem is probably in your shop.
This challenge gets ignored most of the time and blame is probably assigned to something else when your print isn’t looking like it should.
Is it the ink?
Nope. Although that is the number one scapegoat.
Maybe the press?
Everyone talks about their equipment and usually wants to upgrade their line up. But that’s not what I’m getting into today.
The garments you use?
They can cause all sorts of mischief, but that’s not on the docket today either.
Ah…they certainly play a part and are always at the forefront of discussion for issues.
Nope. Not today. The biggest problem in your shop and in the apparel decorating industry is:
That’s right. I said it.
You can’t have great screen-printing without great screens.
So much of what we do in this industry centers on this one item that is critical to the process. But screens are often overlooked in the process for some reason.
Every single day shops stand around their presses trying unsuccessfully to dial in that print. Why does it look this bad? It’s a head-scratcher!
They adjust the pressure, change the squeegee, play with the ink and the off contact. To get a good print they will double, or worse, triple stroke a print to get better opacity.
Maybe even add something to the ink. Some shop production managers all have a “secret recipe” for the ink to get a good print. Curable reducer, chino base, or extender is added for smoothness, while sometimes even a percentage of puff ink is added for opacity.
A few will even burn multiple screens over and over again with the hope that it will randomly sort itself out.
It is all a gigantic waste of time. Band-aids all.
Remember this my friends: the keystone to profitable screenprinting production is your ability to create a perfect production-ready screen on a consistent basis.
There. I said it.
Here’s where the high performing shops outdistance themselves from the competition. On the other side of the coin, here’s where the shop’s that don’t have a decent grasp on the technical side of screen-printing fail miserably.
Which camp are you in?
Probably somewhere in the middle. You know enough to be dangerous. It’s a consistency thing usually.
Often, the right tools are not being used.
Starter shops skimp on the screen room and usually opt to expand into flashier things like a better press, a new dryer or other items. Even more established shops may find themselves overlooking this critical need.
The theory being that “presses are making us our money”.
That’s where the investment goes. When we can’t get enough of our orders printed and out the door on-time, maybe adding another press to the line up will help.
Except that nobody stopped to look at the daily downtime or amount of impressions printed each day by the presses already on the floor.
How much of that downtime problem can be attributed to something to do with screens? What percentage of the inefficiency in production is caused by having to double stroke a print to get decent coverage?
For most shops, quite a lot of it. They just don’t know that because nobody is tracking and analyzing the information.
Here’s a tip.
Less downtime equals more production.
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Do the Math
Determining what to do to change things is often “which came first the chicken or the egg” question.
To show you the value of a perfect screen let’s take a look at some basic numbers. This is an example, and I’m sure your shop metrics will be different.
Example Shop – Week 1
Automatic Press – Sets up ten print locations per day on average. That’s fifty for the week. Average color count for each order is three screens. Takes about nine minutes per screen to set up, but nobody is really checking. Some jobs take longer as there are registration problems with screens. Order size is somewhere between 50 and 144 pieces, so to use easy math we’ll just call the average order size, 100. The press prints at an average of 400 impressions per hour.
Manual Press – Sets up eight print locations per day. That’s thirty for the week. Average color count for each order is two screens. Takes about ten minutes per screen to set up, as the printer is still fairly new. Often needs help to get the registration right too. The manual press handles orders under forty-eight pieces, but the average order size is about thirty. The press prints at an average of 65 impressions per hour.
Basic Shop Floor Math
The shop production team works eight hours per day, but with breaks and lunch, they are only available to print seven hours per day. 7 x 60 = 420 minutes.
- 10 locations x 3 screens x 9 minutes per screen = 270 minutes for screen set up per day.
- 10 locations x 100 piece quantity / 6.66 shirts per minute (400 / 60) = 150 minutes for printing (2.5 hours)
- 150 minutes printing x 100 / 420 = 35.71% uptime printing for the day. Only 35% of the day is spent actually printing shirts.
- Total average impressions = 1000 per day or 5000 per week
- 8 locations x 2 screens x 10 minutes per screen = 160 minutes for screen set up per day.
- 8 locations x 30 piece quantity / 1.08 shirt per minute (65 / 60) = 222 minutes of printing (3.7 hours)
- 222 minutes printing x 100 / 420 = 52.85% uptime printing for the day. Better than the auto, but it is still 52%.
- Total average impressions = 240 per day or 1200 per week
Remember, your shop is only making money when you are decorating a shirt.
So, for Downtime – meaning the amount of the day NOT printing a shirt, would 65% for an auto or 48% for a manual be acceptable in your shop?
Probably not. Er, right? What’s yours?
So let’s fix that and spend effort in tweaking just one thing.
Screen set up time.
Let’s say the shop did an awesome amount of work digging into the challenges associated with their screens.
With improvements and some training on each press, the shop made a great effort and got their set up times down to an average of five minutes a screen.
New Math – Week 2
- 10 locations x 3 screens x 5 minutes per screen = 150 minutes for screen set up per day.
- This just added 2 hours to the production day (270 – 150 = 120)
- 150 minutes print time before + 120 minutes of new availability = 270 minutes for printing daily.
- 400 per hour impressions x 2 hours = 800 extra impressions available per day.
- Total average impressions = 1800 per day or 9000 per week.
- Extra 4000 impressions per week x 52 weeks = 208,000 extra impressions per year.
- 8 locations x 2 screens x 5 minutes per screen = 80 minutes for screen set up per day.
- This just added 1.33 hours to the production day (160 – 80 = 80)
- 259 minutes print time before + 80 minutes of new availability = 339 minutes for printing daily
- 65 per hour impressions x 1.3 hours = 84 extra impressions available per day.
- Total average impressions = 324 per day or 1620 per week
- Extra 324 impressions per week x 52 weeks = 16,848 extra impressions per year
Of course, these are example averages, and real production numbers are more complicated.
Yet, here’s how you prove that reducing your screen setup time can get you an extra 224,848 impressions per year without buying any new press equipment.
This happens with dialing in how you use screens by focusing on the setup time on each press.
It’s like magic.
Push For Lower Set Up Times
If you have any sort of volume in sales and have a packed schedule, pushing for lower set up times and get it under five minutes per screen for your average is how you justify that computer to screen system, registration system, or other capital expenditure in the screen room.
That CTS system works great as all of the screens for an order will be perfectly registered to each other when they are imaged. Using a registration system in conjunction, like Tri-Loc, means they simply lock into place with minimal effort.
For the old way, every minute you spend pressing down with your index finger into the screen to see if the image is aligned with the other screens for the order is a minute that could be spent printing shirts. Those minutes add up.
Do you know your average screen set up time? Or, if you are like a lot of shops, do you just guess?
Telling yourself, “We do ok”, but not measuring this step is delusional management.
How Do You Do That?
For starters let’s look at things from a general perspective in the screen room. There are five main steps in creating a functional screen.
- Emulsion Coating
- Imaging & Exposing
Without craftsmanship in these processes, things will fail in production and you’ll spend a lot of unnecessary time adding some sort of band-aid to the problem.
Chances are you are already spending money because you have never identified this leak.
It doesn’t show up on an invoice. The amount of time and effort in production that is spent fixing bad screens isn’t a line item on your P&L statement.
But it is costing you just the same. Ouch.
This is the number one factor for screen success.
Think about it. What is easier to shear ink through, a screen that acts like a trampoline or one like a hard sheet of glass? The higher the tension of your screen, the less effort (pressure) will be required to pass the ink through the screen and onto the surface of the shirt.
In your shop are you even measuring this?
Most shops don’t.
Sure, they might actually even own a tension meter. But it doesn’t come out of that hard plastic case much. How thick is the lint layer on yours?
Screen tension is a critical component to good quality screen-printing. As such, you need to create screen tension standards for your shop.
They don’t have to be anything super elaborate either.
- Anything under 18 N/cm you don’t use. That’s bottom line standard.
- 18 N/cm – 20 N/cm is only good for one color orders.
- Above 20 N/cm works for multi-color orders
- Keep all screens for multi-color orders within 2 N/cm of each other
- The higher the tension the better.
- If a “just good enough” print is ok, then “just good enugh” tension will work. If you want fantastic, award-winning, prints, then you need to ratchet up the tension level. I’d use Newman roller-frames and higher mesh counts too.
- Nobody on this earth has magic fingers. You can not thump a screen like a watermelon and gauge accurate tension. Professionals use the correct tool. Buy a tension meter.
Band-aids that point toward tension problems
- Having to double stroke your ink instead of one pass. Everytime you double stroke you double the cost of the ink for that screen. You also add to the total production time for the order. This is an inefficient use of time. Doesn’t it bother you that it takes twice as long to print? It should.
- Ever use two underbase screens for coverage? What do you think is driving that?
- Registration issues, but the art lines up perfectly on the film or on the computer. This shows up a lot with the white underbase peaking out from a color and not being able to move the screen around enough to solve the problem. Double whammy if the solution from the printer is to use more pressure to hide that peek-a-boo ink underneath.
- Rough prints. If your final print looks like a lumpy cake icing, this is a tension issue. However, most shops diagnose this as an ink issue. Anytime you need to heat press your print to make it smooth, you might want to take a nose dive into some tension research.
- Lots of pressure needed to print. If your squeegee is doubled-over like a capital letter “L”, that’s not right. The goal is to shear the ink through the screen and have it kiss the top surface of the substrate. With a decent tensioned screen, not much squeegee effort needs to be used to clear the ink. If you can see your print on your platen board, you are diving the ink through the shirt fabric and onto the board. This “hammer pounding the nail technique” affects opacity and usually is why printers double stroke or use a second underbase screen.
This isn’t new information.
However, there seems to be a big gap between folks that grasp this information and put it into practice and those that don’t. Just review any online forum group or message board with shops asking for help with a weird looking print and you can see what I mean.
There are at least one or two posts a day that illustrate this point.
Reclaiming and Coating
These steps go hand in hand with building a foundation for the image we use to print. These are also the two biggest pain in the butt steps in your entire building.
Reclaiming is easily the worst job. It’s like doing dishes forever. Coating screens with emulsion aren’t much fun either, as it is usually a lonely task in a dank room.
However, these are crucial steps in the process as we need the screens cleaned, degreased, and coated with emulsion perfectly. This sets up the foundation for the image.
How dialed in is your process in your shop?
Do you have someone that is detail minded doing this work, or are you like a lot of shops and stick your worst employee on this as a punishment? Maybe you use a part-time kid once a week that is in and out without much supervision?
In essence, you are leaving the cleanliness and quality of your number one production tool in the hands of someone that doesn’t care and is the lowest paid employee you have?
If you don’t think apathy in the area can backfire on you and hit you squarely in the face with a Murphy’s Law skillet I don’t know what to tell you.
- Don’t skimp on products. Buy the best you can afford. Better products might cost more, but the performance of these products will pay off later as they will be easier to clean, or expose, or produce a better stencil than cheaper varieties. Don’t step over a dollar to save a dime.
- Geography plays a part in what to use. Humidity counts. Get a hygrometer and use it to measure the relative humidity in your screen room. Ideally, the humidity is less than 30%. Measure this. Use a commercial grade dehumidifier to control this problem. Don’t forget a room full of wet screens increases the humidity in the room. You will see a spike in humidity after a coating session.
- There is a big difference between how products may work in Mississippi versus New Mexico. Don’t just read what’s on the internet and take that as gospel. Who knows where those people live? Talk to your local supplier about what works in your area the best. Better yet, get that person to come in and train your crew on best practices.
- Clean. This is a messy business and the screen room is one of the messiest. Keep it debris and lint free. Lint floating in the air is what usually creates pinholes. Especially on vacuum table glass. Be meticulous for better results. After being in shops in every corner of the country I can tell you that the best ones are not slobs. Their floors and walls sparkle. There is a reason for that.
- Screen making is a craft and requires precision. Make sure your training and management of the process are up to speed. Screens are the keystone to your entire operation. Do not just let anyone do it.
- Have a firm grasp on the concept of “Emulsion Over Mesh” or EOM. This is the thickness of the emulsion you are coating on the screen. Consistency here counts. Want better quality screens? Upgrade from a manual scoop coater to an automatic coater. A machine will standardize this important step so that every screen will have the perfect coat of emulsion.
- You can measure the EOM on your screens with a tool called an EOM Meter. Your goal should be to get a 12-15% stencil thickness. You want repeatability. Any easy to way to test this to determine your EOM, and set your coating process (1:2 or 2:2) and then see how many screens you get out of a gallon of the emulsion. Let’s say that you get 42 standard sized screens on average for your target EOM. If you are tracking this with a log, and your screen room coater now shows over 50+ screens for the day, you know the EOM is less than it should be. Predictability and consistency matter. Create your standards.
- I am by far not a screen-making expert. To really geek out on this stuff, read anything by Dave Dennings with KIWO, or listen to my The Big Idea podcast with Alan Howe with SAATI
- Talk, read and listen to the experts. Don’t simply take my word for it.
Imaging & Exposing
So let’s assume that your screens are coated and ready to go. The next step in the process is to get the image for the art burned onto the screen.
But before we handle that step, ask yourself this one question.
Is my screen dry?
Sure, it might be dry to the touch. But, let’s compare that to a tomato. A tomato is dry to the touch also, but slice it open and you have a wet, messy problem on your hands. (Thank you, Richard Greaves & Alan Howe, for the metaphor)
Your emulsion has to be 100% dry. Queue the need for an enclosed room with a commercial grade dehumidifier again.
Control The Screen Room Light
I’ve been in shops where they place little thought on UV light sneaking in and pre-exposing the emulsion on screens.
“Why do we keep having screen image problems?”, they say. It’s not hard to wonder.
For lighting, be sure to have the correct UV light filter covers. These will cast a yellow glow in your screen room. A good practice also is to paint the screen room a different color than white. I’ve seen shops use black or even yellow as well.
Vellum, Film, or Computer to Screen?
How you get the image to the screen has a direct impact on the quality of the image to be burned, and placement on the screen.
Currently, the absolute best practice is to use a Computer to Screen (CTS) unit.
This piece of equipment is the number one tool to increase efficiency on the production floor. Any printer that has invested in this workflow upgrade will never, ever go back to using film or vellum.
There are certainly different models and brands on the market for CTS units. Some use a water-soluble ink, others use a wax, and even SAATI has a new unit that uses a laser, to image the screens.
These systems are superior because they place the image directly onto the screen.
Film or vellum is placed on top of the screen and is taped down. During the exposure process light can seep in around the film or vellum and erode the quality of the exposure. This directly affects the edges of your image and halftones. With a CTS unit, this doesn’t happen so you create a better channel.
Also, because the CTS unit locks in each screen frame with three points of contact, the images for a print run are all exactly pre-registered to each other perfectly. If you are a woodworker, this is comparable to a jig. Duplicating this pre-registration on press with a registration bracket allows your crew to quickly get your screens set up in less time than manually registering them.
Finally, CTS units completely eliminate the need for the vacuum table step for exposure and this saves time.
Some CTS models have an LED exposure system built in, so as the screen frame comes out of the machine it is being exposed. The SAATI laser unit exposes and images the screen in one step, without any consumables.
Of course, the use of film or vellum will work. Plenty of shops travel down this road every day. However, if you are creating over 40-50 screens a day you should be looking into getting a CTS unit for your shop.
Rinsing & Washing Out Screens
Another key problem in the screen creation journey is this final step, rinsing and washing out screens.
If your screen-printers have to keep a roll of masking tape, a needle or a Q-Tip handy to poke holes in the emulsion, or tape up and correct crappy emulsion edges, you know the importance of washing out your screens.
This drives home a big problem in this industry and that is underexposed screens.
Do you feel that your shop has a grasp on how to expose screens correctly and what’s involved in ensuring craftsmanship in this critical step?
If your shop has your exposure dialed in properly you can use a commercial pressure washer to blow out the emulsion for the print areas without worry. A quick rinse with some water, a few moments to let it sit, and then WHOOOSHH.
Under-exposed screens show up with pre-mature emulsion breakdowns during a print run. You shouldn’t have to worry about this if you are confident in your process.
- Use an exposure calculator provided by your emulsion manufacturer to dial in your exposure times for each screen. They will happily provide you one, and if you are unsure how to use it, even train you.
- If you are having trouble with under-exposed screens look at your light source. When was the light time you changed the bulb? Commonly, the answer is “We don’t know. We’ve never changed it.”
- After you have exposed a screen if you use a moistened white towel or t-shirt and wipe it around on the side of the screen not directly exposed and any of the emulsion colors come off, you have an under-exposed screen. That rag should not be pink, blue or green at all. (Whatever color your emulsion may be)
- How long does it take to wash out a screen in your shop? Properly imaged and exposed screens should take only a few minutes with a power washer. If you are in the ten-minute+ category, you have problems.
- Use a production log and document the frequency that your press crews are stopping to fix a screen problem. This is the number one tool to use to investigate these challenges because it will tell you when the challenges are showing up. You can link this to some change in your process, who created the screens, when a different brand of the emulsion was used, or some other scenario.
- After washing out the screens, the next common step is to block out and tape. With a CTS unit, you rarely need to block out a screen for any problem pinholes or areas on the screen. If you are using aluminum static frames, you can also invest in screens that don’t have to be taped and avoid this step. Imagine the freedom of not having to add tape to screens or pull it off in reclaim!
A Final Word
So, if you have made it this far in this article, congratulations. There was a lot to cover, but yet I barely skimmed the surface on this topic.
I would highly encourage you to spend a good chunk of time examining this process in your shop.
Take an honest assessment. How much of the care and craftsmanship of your shop originates in this often forgotten corner of your building?
Who do you have in charge of this process, or doing the work? Hopefully, you can say they are one of your top employees. If not, does the level of employee in your screen room equate to the craftsmanship and consistency of your screen room output?
Do you honestly feel you have the right tools and techniques down to have a badass screen department?
If not, what are you going to do about it?
Your screens are the fuel you are putting into your racecar.
Which means, either they are allowing you to go a million miles an hour with your hair on fire, or you are that clunker on the side of the road with the engine that powers the coughing, wheezing, barely-functional wreck.
How many racecars are passing you today?
“In boxing, they say it’s the punch you don’t see coming that knocks you out. In the wider world, the reality we ignore or deny is the one that weakens our most impassioned efforts toward improvement.” – Katherine Dunn
“We cannot solve our problems with the same thinking we used to create them.” – Albert Einstein
“Measure what is measurable, and make measurable what is not so.” – Galileo Galilei
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Nice work Marshall!
Great article! I’ve been around the block a few times now, and have experienced many screen rooms over the years. (40+ years). The shop that I now work for, over the past 17 years, has had capabilities that most local shops don’t. I do simulated process separations for them, and have always had success in the screen room, until just the past year. WE sold our Olek 6000watt metal halide, and vacuum frame, and purchased a new I-image, CTS with the LED exposure system. We could no longer get the detail to wash out of the screens, and 20 to 30% of the halftones are gone. As in over exposed…except that the screen emulsion is soft and breaking down prematurely…as in under exposed. My quess is that the LED light is penetrating through the printed area. Also, in order to get the image area to wash out; you must use a pressure washer. Personally, I have never experienced this before. I’m use to the image desolving out with just a mist spray, and all the halftones dots are open, as they should be, with a strong stencil. I noticed that the screen room light filters were also changed out from UV proof, to yellow BUG LIGHT filters. I was told that they should work fine, and not cause an issue.We use the same dualcure emulsion that gave us the best results with our 6000w metal halide. I’m sure there are some adjustments that the screen room tech, can make, to get our quality back up to where it was, in our past. Unfortunatuly, the new people in charge, don’t know how, and the new tecnology seems to be dumbing all the newcomers down. All the screen making problems that the veterans learned how to solve, are now issues again, and the solutions have not been found yet. Don’t tell them that The BUG LIGHTS are pre-exposing the screens. The screen room is the most important part of a businesses success, in this industry. But the art department and printing department, must also, be able to follow their lead. It’s the screen room that determines the shops limitations.The better they are…the better the whole shop.
I would be looking into two areas…first you should be able to wash your screens out easily. This sounds like an emulsion or curing issue. Also, I’m not sure what bug lights you have…but you want to be able to block the UV wavelength that hardens the emulsion. Thanks for reading the article and taking the time to comment. Keep working the problem…