The Screen-Cleaning Boxing Ring
Do green screen cleaners actually work? This article compares them to conventional cleaning products and describes how to use them effectively.
Can newer, safer, greener cleaning technology really knock out tried and true, older, petroleum- and caustic-based cleaners? Let’s envision this boxing match: Without further delay, ladies and gentlemen, in this corner the current champ, weighing in with an impressive record, holding the titles of Earth Pollutant and Ozone Puncher, is Petroleum Pete. And in this corner the contender, seeking to displace the champ, weighing in at an incredibly fast-growing rate, holding the titles of Renewable Resource and Green Earth, is Enviro-Friendly Ernest. Even though this is a battle you are not likely to see on your TiVo, screen-printing shops across the globe are coming to this fight. They are faced with having to decide which, if any, green cleaning products can be cost effective, work, and, in the end, get the job done with the least amount of fuss possible.
Let’s be honest. Of all the operations screen printers perform to keep their businesses strong and growing, most shops probably give the least thought to their cleaning operations. Cleaning areas are tucked back in a corner and generally look like World War III has begun. But cost effective, good screen cleaning means better printing performance, longer lasting screens, and more money in screen printers’ pockets! Now, on to the match! Ding ding!
Round 1: Ink cleaners and degraders
There are hundreds of ink cleaners on the market to clean numerous types of inks used in screen printing today. They generally fall into three categories: petroleum, green, or a petro-green blend. Petroleum cleaners are usually highly volatile, potentially dangerous, not earth friendly, and made from the by-products of the refining process of crude oil.
Green cleaners generally are not volatile, are designed to be earth friendly, and are made from renewable resources such as soybeans, corn, and oranges. Petro-green products are a blend of petroleum and green products that generally are less volatile and provide manufacturers of petroleum products with a method for making their products less dangerous to use. Being practical, screen printers just want a cleaner that is affordable and works well. But sometimes it’s not easy to select just the right cleaner to achieve this.
As the previous undisputed champ, petroleum cleaners have been used for many years. They are viewed as effective, inexpensive, and readily available. But in today’s world we have learned that petroleum cleaners come with heavy baggage and possible problems that can cause you to pull your hair out. Have you ever had an emulsion that would not clean out of the screen, or that came out in pieces? If so, you are probably one of many screen printers using a petroleum or petro-green cleaner (sometimes referred to as hot solvents) in your shop.
In their day, there is no question that hot solvents were the best cleaning option available. But that was before there were alternatives—other contenders. Petroleum and petro-green cleaners can have devastating effects on certain types of emulsions, causing you headaches and adding the cost of new screens. In addition to possible production or cleaning problems, hot solvents also bring a variety of hazards that shop owners must be cautious about (Figure 1). High VOCs (volatile organic compounds), high flash points, worker health and safety issues, and environmental impact are on the top of the list. The bottom line is that, while petroleum and petro-green cleaners clean well and appear to be cost effective, they can also cause avoidable problems.
Previously the under dog in the ring, green ink removers have been around for a couple of decades, but have gained more popularity in recent years. Earlier they were viewed as being more expensive and less effective; however, technological advances have made this presumption untrue in today’s world. When used properly, green ink cleaners can be hidden gems with a big pay-off.
Green cleaners require a little different mindset when they’re used to clean screens and can’t be used exactly like their petroleum counterparts. Have you ever had a situation where you wanted to change colors but the tape wouldn’t stick after the ink was cleaned out? This is a common situation when a green cleaner is used. Where hot solvents have low flash points and quickly evaporate from the screen, green cleaners generally require a water-dampened wipe to remove the last of the solvent residue.
So what about the cost? In many cases green ink cleaners are more expensive up front, but cheaper in the long run. In today’s market you can buy a gallon of mineral spirits or xylene for less than the cost of a gallon of a green cleaning product. However, a green cleaner may require 0.25 oz of product to clean a standard sized screen. If used correctly, that’s 512 screens/gal. How many gallons of mineral spirits would it take to do the same number of screens?
Round 2: Emulsion and stencil removers
Even with today’s multitude of blue, pink, green, purple, single-part, diazo, and dual-cure emulsions, one thing remains the same—there are not a lot of new chemistries for reclaiming an emulsion. Back in the day, when of my grandfather walked to and from school, uphill both ways, in three feet of snow, screen printers used bleach to remove emulsions. Bleach worked, but its use had far too many disadvantages. If not careful, a worker could become disoriented—or worse—from the bleach vapors, and it took a long time for the emulsion to be removed.
Even today, there are only two primary environmentally friendly chemistries on the market that will remove emulsions and stencils. They come as a liquid or in crystal or powder form. The trick is in how you use them. Every emulsion or stencil requires its own dilution rate of one of these two chemistries to remove a properly cured emulsion. Some manufacturers make a one-size-fits-all emulsion reclaimer, while other manufacturers tailor their emulsion reclaimers to specific emulsions. Not all emulsion removers are the same (Figure 2). Even though most manufacturers use one of the two same chemistries, the trick is finding the one that removes your brand and type of emulsion effectively. A tip: If your emulsion remover does not remove your emulsion with minimal effort in less than a minute, you should look to replace your emulsion remover.
You can decrease your eco-footprint even more with a special reclaiming process. For many years, the screen-printing world had asked for a product that could remove ink and emulsions in one step. Almost five years ago, the manufacturing world met that request. Interestingly enough, the chemistry used relies heavily on the same one used in current, environmentally friendly emulsion removers. The process works by placing your screen in a tank and soaking the screen for a short period of time. Then you use a low-pressure power washer to clean the screen out, thus combining two steps into one step.
The tank traps and contains most of the emulsions and inks, keeping them from entering the water-discharge system. After reclaiming many screens, when it comes time to empty the tank and start with a fresh batch of reclaimer, shops use a filter system to remove much of the trapped emulsion and ink, further reducing their eco-footprint.
Something to remember when using these systems is that they do not degrade the ink from the screen; they only soften the ink. Any type of chemistry that degrades ink can also remove the adhesives from around the frame edge. It’s not fun to pull the screen out of the tank and find the mesh floating away from the frame. These systems simply use emulsion-removing chemistry with blends of degreasers. The emulsion remover does its job, and the degreasers loosen the ink, enabling it to fall off of the screen or be easily blown out of the screen.
Round 3: Haze and ghost removers
It’s unbelievable how many screen printers never remove the ghost/haze from their screens when reclaiming. It’s such an important step that takes very little time, makes your screens last years longer, and keeps you from having pinholes and other problems down the road. You will seldom stain a high-quality mesh. Rather, a haze image is ink that is trapped in the knuckles of the mesh, creating a light visual image of the artwork that was printed.
Most of the time, the reason given for not dehazing is that the caustic dehazing products on the market today are incredibly hazardous and would the screen if not watched like a puppy roaming around on new carpet. Thus, many screen printers choose to dehaze once or twice a year—or not at all. Caustic dehazers work extremely well to take a haze or ghost image out of a screen mesh, making the screen look new and pretty again. But they work primarily by eating away a small bit of the surface of the mesh, thus helping to release the trapped ink between the knuckles of the mesh.
Continually eating away at the mesh eventually will weaken it, causing future print-registration problems. In the most severe cases, if you were to leave the dehazer on too long, you would find a major tear right across the mesh, causing you to remake the screen (Figure 3). In addition to possible damage to the screen, there are environmental and health concerns associated with caustic dehazers. Be sure to follow all instructions very carefully when using a caustic dehazer, and use proper disposal methods to decrease the impact on the environment from your cleaning and disposal.
Green dehazers work differently (Figure 4) and, therefore, must be used differently to effectively clean away the same haze image that a caustic haze remover eats away. If you were to pick up a green dehazer today and use it exactly like its caustic counterpart, you would find yourself wondering whether you should return the product. Used properly, a green dehazer will remove a ghost/haze image just as well as a caustic dehazer. The difference is green dehazers are formulated to work on the ink without harming the mesh or the individual who is cleaning the ghost image.
To keep from being frustrated, follow some basic principles that apply to most green dehazers. First, remove your haze images every time you reclaim your screens. There are lots of variables in what can occur, but in most cases when haze images are left in the screen with the intent to clean them out maybe three or four reclaimings later, they become very difficult, if not impossible, to remove. Secondly, the drier the screen, the more effectively the dehazer will work. Water that is left on the screen can dilute the dehazer, making it less effective. Lastly, green dehazers take a little longer. Be patient, and let the product you are using go to work. In some cases you may be looking at a minute to two minutes longer than a caustic dehazer.
Conclusion or concussion
Although the fight still goes on, the champ is weakening and the contender is getting stronger. Clearly, petroleum, petro-green, and green products all have their advantages and disadvantages. It is up to the shop owner to evaluate these and choose the best products that are cost effective, work well, and are safer to use. Choosing the wrong product can waste your money and leave you and your staff feeling frustrated, tired, and simply unhappy in doing your jobs.
Environmentally friendly, green products have come on strong. Today might not be their title shot, but they are on the fight card to stay and have the potential to claim the Cleaning Championship with a knockout.
Jason Davenport is the marketing manager for Bloomington, IL-based Franmar Chemical, Inc.