Let’s face it: screen printing produces waste. No matter how hard printers try, the process of screen printing produces waste in the form of ink, emulsion, chemicals, and more. The best way to keep screen printing as Earth-friendly as possible? Dispose of this waste properly. Here’s a guide to doing it right.
Proper hazardous waste disposal may involve a commercial waste disposal service. There are plenty of uses for in-house recycling too: packaging, empty (and clean) containers, and more. No matter the disposal method, a proper waste disposal strategy begins with knowing the following information:
- The chemicals you’re using and their potential hazards
- The city, state, and other regulations that apply to disposing of these chemicals
- The waste disposal options and how they comply with applicable laws and how they meet the needs of your operation.
First and foremost, the chemicals used during the screen printing process make a difference. Cleaning ink off screens and reclaiming those screens requires using chemicals. Some chemicals are a little kinder on the environment than others. Sgreen chemicals strive to be friendly to the environment and the printer, while still getting the job done.
Take into account factors such as the type and volume of printing, as well as performance requirements. It’s also important to be familiar with the MSDS on inks and chemicals. Every chemical product page includes an MSDS sheet, so printers know how to dispose of the chemical correctly.
Every shop produces some waste. For example, ink degraders don't completely dissolve. When washed down the drain, the ink degrader is still in the water. It’s important to get to know the chemicals and local waste management standards.
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RULES AND REGULATIONS
Strict rules for hazardous waste disposal exist at local and state levels. These can vary based on location. Printers should get to know the regulations in their area and comply with them.
Here’s an example of a regulation that can affect screen print shops. Some chemicals have a flash point. This means they are potentially flammable. The fire marshal or OSHA can require printers to dispose of the rags and t-shirts used to clean screens in a specific container rather than put them in the dumpster because of their potential flammability. It’s smart to use chemicals that have a high flash point (150°F and above).
When using chemicals with low flash points, it’s best to have a service come help dispose of them properly. The good news is that the industry has evolved and many chemicals with low flash points have been replaced.
So no screen print shop is waste-free, right? There are steps printers can take to minimize waste in a shop. Misprints can be cut up into rags and reused. Once the rags have become well-used, learn the county's, city's, or state's regulations on disposing of chemical-soaked rags to ensure proper disposal.
Another great way to minimize waste is ink management. The more ink that’s left on a screen at the end of a job, the more chemicals are used to clean it up. Card off as much ink as possible so only a couple of spritzes of cleaner will do the trick. This will save printers money as well as reduce waste.
Can’t dispose of waste within a shop’s recycling system? It’s time to call a waste disposal service. These services, such as Safety Kleen, can facilitate compliance. They will haul away liquids and solids that have built up from recirculation and provide printers with a manifest letter verifying how the waste is being handled.
Waste containers can be provided by the service or bought by printers. Again, depending on the rules governing waste disposal in the area, or if the shop is recirculating chemicals and putting the solids that settle into drums, there may be local companies that can take them away.
One of the best ways to minimize the amount of chemical waste is to use an automatic screen cleaning machine and a recirculating chemical system. Here’s how a recirculation system works.
The system functions to minimize waste by decanting used chemicals. The matter is collected in a container and the solid waste settles to the bottom. The remaining clear liquid chemistry on top is siphoned off. Then it's topped off with fresh products for reuse. This reduces the number of chemicals poured down the drain and reduces chemicals used in general.
When reclaiming, all the water and chemicals, ink, emulsion, etc. goes down the drain. Save the plumbing by investing in a water filtration system.
A filtration system filters solids out of the water, keeping your pipes in good condition. It is a series of filters that capture solids and stop them from entering pipes. The main goal is to catch the solids. These are emulsions, inks, and pigments. Every time a screen is rinsed out or reclaimed, the emulsion is going down the drain. Inks often remain congealed as a glob and sometimes even pieces of tape can get washed off and go down the drain. Without a filtration system, all of these go through the pipes.
So how does it work? Filtration starts with a PVC pipe, which attaches underneath the washout booth, that funnels the water to a tank with filters designed to catch different sizes of particulate. The first filter catches all the big particles. Then the water goes through three reusable screens: 110, 156, and 200 meshes. Next, the filtered water flows into a holding tank where a high-powered industrial sump pump is triggered, pushing the water through the final two stages: a 70- and 20-micron disposable filter.
Once the refuse has gone through this six-stage filtering process, the water has been strained multiple times and most solids have been removed. Any remaining particulate has been reduced to 20 microns (0.000787402 inches), making it small enough to go down the drain without constantly worrying about clogging.
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In conclusion? Be proactive. Knowing the regulations in the area and knowing shop practices helps to reduce waste and dispose of it correctly. No shop can produce zero waste, but all shops can do their part to dispose of the waste they do accumulate. A little research and a responsible approach upfront can save shops money and a lot of headaches in the long run.