by Mark Coudray
Misprints, everybody has them. Some days are better than others. Some jobs are always a problem. How much is it costing you? A lot more than you may think. In this month's column I would like to address some of the common causes of misprinted goods and how to avoid them in the future. With very little effort you can make a big dent in an area that traditionally sucks your profits away.
Measuring the sources of misprints
Most printers will continue printing forever without looking for the true causes of misprinted garments. There is too much pressure to get the work out the door to really delve into the causes. In other words, they are too busy making mistakes to take the time to correct them.
Correction is the key to the whole issue. I am not talking about putting more tape on the back of the screens to cover pinholes, I'm talking about truly getting to the bottom of the root cause so that you don't have to stop and tape the screen.
There are two main concepts to accept if you are to fix the majority of your problems. The first is in finding a way to keep track of the reasons the misprint occurred. The second is in getting your employees to accept the responsibility for doing a good job. The first is fairly easy to do, but the second can take some work. Identifying the sources of your spoiled printing can be as simple as setting up a sheet at the end of the dryer and recording the quantity of the order and listing the reason a print was spoiled, along with the quantity that corresponds to that cause. For instance, the print run was 144; there were 2 folded images and 1 out of ink. Keep a running log for a week or two, and then total up all of the common items. You will begin to see a pattern. For one thing, you will see that there are really a limited number of sources. For another, you will note that there are only several causes that account for the majority of your misprints. By attacking those areas you will reduce the majority of the problems.
Besides determining what is causing the misprints, we have to look to the employees. They are the ones that are doing the printing and ultimately they have a direct involvement in the cause of the spoilage. This may be intentional or unintentional. Getting them to understand that they are responsible is the second major part of the correction program. Having employees care about the quality of their work is part of it, but more importantly it is getting them to understand that part of their job requirement is to only pass on perfect work to the next operation. When you keep track of the causes of your misprints you will find that a great deal of them are caused by trying to fix problems from early on. An example would be trying to make bad art look good.
Ways to reduce misprints
The process starts well before the shirts are actually printed. Actually, when the order is taken. Is the information correct? Have the customer review the order before it is submitted into production. Have them sign it and give them a copy. If they cannot do it in person, have them sign a faxed copy. Don't proceed without approval. I can't tell you how many times we have caught mistakes this way. This may sound really basic, but it is exactly the type of assumption that causes trouble.
The ink colors that the customer requests for the image should be clearly identified, either by PMS number or by an internal reference so that everyone involved knows that "Royal Blue" is really PMS 286. Putting down simple colors like red, green, yellow, and blue are not good enough, especially if the customer has a number of jobs, or is rerunning a job from the past. Exact color description help in duplicating the image in the future. You still have to match the required color, but at least you know what color you are supposed to be using. If you intend to rerun a job, put a small amount of the actual ink colors on the spec sheet and dry it. This is the definitive sample that no one can argue with.
Have a clear idea of what the customer expects
Knowing exactly what the customer expects will go a long way to avoiding the long delays on press and arbitrary printer judgements. Guessing flirts with rejection. Keep it simple and clear. If there is any doubt, have it clarified. This is one of the areas where printers don't like to slow down. Clarification interrupts the thought and job flow. The basic instinct is to make a call and go for it.
Valid change orders
Customer changes not communicated to production is another primary source of error. Having the right information is the most basic starting point for accurate production. Simple changes in ink color or stock will totally ruin a job if the printers aren't aware of them. Changed orders need to be clearly identified with some type of colorful sticker with initials, dates, and what the changes are. It also helps to make a written copy of the change and fax it to the customer. Include the change order and the fax verification in the job ticket. Stapling the change order to the original work order makes sure that everything is together.
If you do contract printing it is very common to have many last minute changes. Stock gets moved from one design to another, sizes and quantities change, and general confusion rules. By stapling consecutive change orders to the original ticket you can more easily keep track of what the final requirements are. It also helps to use either letter or number designations to verify what the current valid order is. For instance, Change Order D or Revision 2.0 are examples. If there is any doubt or confusion you can call your customer and verify what the current valid change or revision is. Make SURE that the person making the change is documented by date, time, and name.
The right image
If the customer has more than one image in your library it is important to know which one they want. We recently found a customer design that had no less than 26 different color ways (combinations.) The customer had changed the color combinations for variety, and they had been noted as customer changes. Pretty soon it was too complicated to keep track of, and an eventual disaster occurred. To solve this in the future our customer service rep made color copies of all the designs, gave them design numbers, and presented a bound book to the client to help with future orders. Our front office has a duplicate book for verification. Smart thinking helped turn around a touchy situation and strengthen our relationship with a good customer.
Workflow and general housekeeping
The workflow and general housekeeping in the shop are primary sources of trouble. While I am a big believer in a clean working environment, I am not a fanatic about it. When goods start to be spoiled with smeared ink and lint in the design areas, then it is time to get down to housekeeping. If a shop is allowed to build up dirt, lint, rags, ink cans, etc. it will be a huge effort to get it under control. If you keep after it on a daily basis it never gets to that point. Take a look around your shop. Most likely you will find one or two individuals who are the worst offenders. Likewise, there will be employees on your staff that keep things up. Make a conscious effort to not let the shop get out of control.
Crowded aisles and dirty surfaces will spoil garments as they are being moved about. Often the printers and packers are not aware of any problem. Since most shops use plastisols, the situation is compounded. Wet ink smeared onto a stack of shirts as they are moved will continue to transfer to more clean garments. The stackers at the end of the dryer are watching the design, not hidden areas of the garment. It is usually the customer that comes back with a box full of shirts that need to be blown out. This is both embarrassing and unprofitable to you, and results in a loss of confidence on the part of the customer.
On the press the biggest offenders are spray adhesive and spilled plastisol. Overspray from the adhesive mixes with lint from the shirts and clings to everything. Through the normal printing process this lint falls onto the garments as they move around the press. Eventually it finds its way onto the screen and creates a void in the image. With process color this can be an unretouchable situation. The more lint that you have on the press, the more it will impact your productivity as well as the quality of the image.
Spilled plastisol usually shows up on long sleeve shirts, sweatshirts, or oversize garments that drag around the press. If the ink falls into crevices or cracks on the press it will continue to accumulate until it is very difficult or impossible to remove. If you spill, wipe it up. Get into the habit of trying to wipe up a smudge of ink every time you have a rag in your hand. If you wipe down the screen for lint, look for something else to wipe before you return to work. This simple approach will help keep the press looking and functioning spotlessly.
Ink cans and buckets
Accumulated plastisol on the lip and outside of ink cans tends to spread everywhere. This is one of the hardest areas to control because the ink buckets are irregular on the outside and have many areas where the ink can collect. It takes special care to keep this under control. At the very least make sure that the sides and bottom of the cans are wiped down so that they don't track the ink whenever the can is set down. Nobody likes to deal with dirty ink cans. This is one of the biggest negatives in working with plastisol. Since it never dries, it is always available to land on something.
Keeping the original artwork clean is the first step in avoiding problems with screens. Dirty backgrounds result in specks on the film and pinholes in the screens. The cleaner the art, the easier it is to maintain. This is becoming less and less of an issue as more work is being done on the computer. If you are still using mostly darkroom materials, take your time and do it right.
Try to avoid multiple layers of film and tape, as they will cause weak screens, pinholes, and premature breakdown. Good technique pays big dividends in the long run. Don't make the next guy clean up your problems.
In of screen making the two biggest challenges are in reduction of pinholes and the elimination of weak stencils. Pinholes are one of the key items that plague screen printers. This is usually because the screen area is dark, wet, and dirty. It is one of those areas that we tend to "sentence" employees to.
The biggest causes of pinholes are in dirty film positives and dirty exposure glass. While it is true that degreasing and coating techniques can contribute to the problems, simply making sure that the film and glass are clean can eliminate most pinholes. Once the pinholes appear in the image you need to block them out. This is tedious and time-consuming work. If there are a lot of them it is easy to skip over the small ones and concentrate on getting the biggest. This is a shortcut that rarely pays off. Pinholes will continue to develop and appear throughout the run. Eliminate them at the beginning and save yourself a great deal of grief. Like the smeared ink from the press, the customer is likely to bring it to your attention.
Next is proper exposure. If your lamp is old and weak, or if it is of the wrong wavelength for proper exposure, your stencil will have latent pinholes. These are weak areas that breakdown during the run, causing you to stop, tape the screen, and blow out the shirts. It is frustrating and nonproductive. If you notice that the edges of your film appear after a certain number of prints, it is a good bet that you are under exposing your screens. Check the last time you changed the bulb, it should last 6-9 months or 1000 hours, depending on your use. If you do not use a mercury vapor or metal halide bulb, this is a good reason to up this item on your wish list of tools.
Another major area is screen tension. I can't stress enough how important this is in controlling registration and image sharpness. The absolute lower limit would be 25 N/cm. Below that tension there is too much capacity for uncontrolled movement in the mesh fiber itself. Registration drift and color inconsistencies are the primary indicators of low mesh tension.
Another major cause of misprints is the mechanical condition of the press. The most obvious area is in how tight the machine is. Registration can be elusive and difficult to track down. Check the locator bearing and the locking fork for lint, adhesive, and grease mixed together. Even very small amounts of contamination can cause big registration headaches. Everyday you should wipe the bearings and the fork of accumulated lint and adhesive. Grease the fork surfaces to insure proper lubrication. It is very common for neglected forks and bearings to accumulate so much lint and dirt that the steel surfaces of the fork will wear groove from the constant abrasion of the lint/adhesive mixture. Once that fork is grooved, your register goes out the window. This is much more common on automatics than it is on manual presses.
Pallet level and parallel is also very important in eliminating misprints. Whenever there are two nonparallel surfaces there is the opportunity for distortion and flex. This results in registration variance and image smearing in the worst cases. The more critical your work becomes, the more important the mechanics of the press are. If you expect high performance printing, it's necessary to have high performance preventative maintenance.
Reduction of misprints is an on going process. You never reach the end. What you are willing to settle for is up to you. What is reasonable? Most printers are working in the 1% - 2% range based on gross dozens printed. At the end of year a typical automatic shop will produce 500,000 to 1,000,000 prints. Settling for 1% amounts to 5,000 - 10,000 misprints. A good number to shoot for would be 1/10 to 1/4 of 1%. Most good contract printers that are under control routinely fall within this range.
About the Author
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Mark is founder and President of Coudray Serigraphics, a textile screen printing company and Coudray Graphic Technologies, a digital imaging and prepress supplier to the industry. He was inducted into the Academy of Screen Printing Technology in 1989 and has served as Chairman of the ASPT twice. In addition, Mark is the recipient of 18 SGIA Golden Image Awards, 2 Swormstedt Awards, Magnus Award, and the Parmele Award (2001). He is past SGIA Chairman (2000). He has served a total of 24 years as an SGIA Director. Mark is a noted industry author with Screen Printing, Impressions, Print Wear, Images, and other trade publications with over 275 articles, columns, and technical papers as well as an industry presenter at tradeshows, conventions, and technical symposiums. He is best known for his extensive work in controlling color halftone printing, quality, and production management of the screen printing process.