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water pouring out of drain onto filtration system

Disposing of Hazardous Screen Print Shop Waste

The screen printing process creates waste, particularly in the form of inks, emulsions, and the chemicals used to clean them off screens and tools. Some of this waste is hazardous. As awareness of environmental and safety concerns continue to grow, so does the importance of having a plan for properly disposing of it.

To properly dispose waste may involve using a commercial industry waste disposal service and/or its proprietary products, your own in-house recycling system or, mostly likely, a combination of the two.

Either way, a sound 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.

CHEMICALS

Ink needs to be cleaned off screens, stirring sticks, goop scoops, buckets, etc. Various types of screen printing and cleaning chemicals exist on the market for this process, some of which are more environmentally friendly (like Sgreen®) and/or recyclable than others.

Factors such as the type and volume of printing you’re doing and performance requirements are key considerations in product choice. It’s also important to be familiar with the MSDS on inks and chemicals. If you opt to use a waste management service, you will need to provide this information to them.

In most cases, for instance, it is necessary to use a product like an ink degrader that will enable the ink to be removed. The problem is that these products only temporarily break up and dilute the ink, so it washes off rather than truly being “dissolved.”

When the tool is rinsed with water, the ink and any other chemicals that have been washed off go down the drain. If this waste water is collected in a tank or container, it re-congeals into sludge.

Every shop produces some waste. This is true even if you’re recirculating your chemicals. Therefore, the goal has to be to generate the least amount of waste as possible.

LEARN HOW TO DO ECO-FRIENDLY SCREEN PRINTING

RULES AND REGULATIONS

There are strict regulations governing hazardous waste disposal. They exist at local and state levels and can vary based on where your shop is located. It is up to you to learn if and how these rules apply to your operation. You are responsible for the chemicals used in your shop from cradle to grave, including their proper disposal.

Some chemicals have a certain flash point, for example. This means the fire marshal or OSHA can come in and require you to dispose of the rags and t-shirts you clean your screens with 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).

Some of ink cleaners for solvent or plastisol inks will evaporate quickly and have a low flash point. Ink cleaners with low flash points will need to be disposed of in a flame safe bin. If you're using these chemicals in volume, find a service to come in and dispose the chemicals properly. Luckily, the screen printing industry has progressed and many of these low flash point chemicals have been replaced with gentler chemicals that are just as effective as traditional cleaners. 

Certain procedures and products minimize waste and disposal issues. If you have misprints or abandoned orders, cut those shirts into rags. Use cleanup cards to remove excess ink off screens and use a screen cleaner to wipe off the rest with the t-shirt rag. Once the rags have become well-used, learn your county's, city's, or state's regulations on disposing chemical-soaked rags to ensure you properly dispose them.

It’s also about ink management. The more ink that’s left on your screen to be scraped out, the more chemical you’ll use to get it out. In the end, it'll make the rag much dirtier quicker, and more waste will be generated. Remember, waste is simply overuse of product. When you're able to dial in the amount of ink you're using with each job, you'll save more money on ink in the long run since you'd be throwing out less ink. 

Excessive ink waste is magnified in larger operations: it's why a sound disposal strategy is essential.

person pouring emulsion remover in dunk tank

Golden Press Studio uses green chemical Sgreen® Emulsion Remover in their dunk tank.

DISPOSAL OPTIONS

A waste disposal service, such as Safety Kleen, can facilitate compliance. They will haul away liquids and solids that have built up from recirculation and provide you with a manifest letter verifying how your waste is being handled.

Waste containers can be provided by the service or you can buy your own. Again, depending on the rules governing waste disposal in your area, if you’re recirculating your own chemicals and putting the solids that settle into drums, there may be local companies that can take them away.

RECIRCULATION SYSTEMS

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. If your volume doesn’t justify an automatic cleaner, a recirculation system can be purchased separately.

A recirculation system basically functions to minimize waste by decanting used chemicals. 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 product for reuse.

You’re not only generating less waste and reducing the amount of chemicals you’re putting down the drain, you’re cutting down on your chemical purchases and spending less since you are reusing chemicals.

WATER FILTRATION

When you reclaim screens, quite a bit goes down the drain — inks, emulsions, chemicals, etc. To save your plumbing and the environment, a water filtration system is the best way to go because it proactively addresses disposal requirements and regulations.

Used in conjunction with proper screen-making and cleaning practices, a filtration system filters out solids such as tape, raw and solidified ink, and cured emulsion. Waste water is caught as it comes out of the sink and sent through a multistep filtration process before it is sent to septic tank or the city sewage treatment facility (or even laid outside to dry and harden for solid disposal). Once again, much depends on your shop’s location.

The bottom line is to be proactive. Know the agencies impacting your operation and their rules with respect to the products you’re using. Talk to distributors and manufacturers about how they deal with their (larger-scale) waste. A little research and a responsible approach upfront can save you money and a lot of headaches in the long run and position your business for a successful future.

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