The battle between your health and the quality/durability of your prints is not a new one. And after talking with a number of industry leaders the last few weeks, it seems the battle is still going strong. My goal was to gain a thorough knowledge of the ink choices for your solvent printer. I think you will find this interesting because on one hand you do not want to hurt yourself or your employees, but on the other hand, how bad can it be?

 

First, let’s review solvent inks. Solvents serve two purposes. The main purpose is to carry the pigments to their destination—your prints. (The water in aqueous-based inks also serves as a carrier.) But solvent carriers also “bite” into plastic-based substrates (such as vinyl) allowing the color to bond with the plastic in a fairly permanent way. That’s why they are so commonly used for outdoor graphics. The carrier may make up 40 percent to 70 percent of the ink’s volume. 

 

Manufacturers have been developing more human-friendly solvent-based ink solutions, such as eco-solvent, light solvent and/or mild-solvent formations. (Photo courtesy of InkTec)

The carrier, in most cases, must be evaporated off of the substrate after the ink has been jetted. When a toxic solvent carrier is used, fumes from this process must be vented out of your shop to prevent harm to you and your employees.

 

Next, let’s review some terms. HAPs is a government acronym that stands for Hazardous Air Pollutants. The Environmental Protection Agency provides a list of chemicals that fall under HAPs. If a solvent ink contains one or more of these listed chemicals, it contains HAPs. For example, nickel, a common component in yellow inks that offsets fading, is posted on the HAPs list and is a carcinogen.

 

The acronym VOCs (Volatile Organic Compounds) is another government classification representing compounds which, when emitted into the atmosphere, can react to form harmful ozone. But not all VOCs are hazardous since some do not create ozone. 

 

Searching for Solutions

For years ink manufactures have been working to develop more human-friendly solvent-type inks, and have created a number of inks that are much less toxic, yet still perform well. Formulas have improved drastically over the years with manufactures now offering low VOC, low odor, nickel-free and HAPs-free formulas. Often the trade-off is between safety and performance, but that is changing as these formulas improve and different, less harmful solvent agents are employed.

 

If your shop is running a solvent-based printer, you should also install a venting system to make sure the work environment poses no health threats to your employees.

Years ago, hot-solvent inks commonly employed cyclohexanone as the carrier and were used in grand-format solvent printers such as the NUR Blue Board. These inks were rich in VOCs and all had multiple ingredients seen on the HAPs list. They were so strong they could burn into just about any plastic and leave its mark which made them very effective for outdoor applications.

However, the solvents in those inks were not only dangerous to work around, but were often too much for the printheads which could melt and break down. Soon the industry came up with different (less aggressive) solvents to use as carriers.

 

Later, manufactures came to market with so-called eco-solvent, low-solvent and mild-solvent printers and matching ink formulas that offered low odor and lower VOCs. They were often presented as greener or “healthier” inks, but, most eco-solvent and mild-solvent inks still contain some VOCs, and most use nickel, and so could not be called HAPs-free. Yes, the ink might not smell like the hot solvent, but it could still have hazardous fumes and potentially harmful ingredients.

 

However, a growing number manufacturers are starting to offer inks with a HAPs-free claim. INX Digital, for example, offers its range of ECO formula inkjet inks, and A.T. Inks sells a line of “Bio Inks” which are sold as being HAPs-free. Also, Seiko recently introduced its new Seiko IX ink which is being touted as a true HAPs-free ink. Additionally, Epson sells a nickel-free solvent ink called UltraChrome GS which, though not totally HAPs-free, is very low in VOCs. 

 

The strong cleaning solutions used to maintain solvent-based printers can be hazardous as well. Be sure to take precautions when maintaining your printer.

Staying Safe in Your Shop

It might be a good idea to have your shop tested for airborne hazards. Most states have a government office that specializes in hazardous environments. Here in Massachusetts we have an office that sends out a person with a machine that tests the air quality. They give us a report of how many parts-per-million (PPM) of chemicals might be present, and shows what levels are acceptable for the work environment. 

 

We have a separate room for our solvent printer and in that room we have a vent that moves solvent-laden air outside. Our test results were 20 percent of what was acceptable (we passed with flying colors). The message here is if you have the printer in a small room with two employees in that room and you print all day long, then you are asking for trouble. If you have the printer in a large room with a good airflow then the PPM might be so low you cannot even measure the solvent. 

 

You also have to consider your whole safety procedure—cleaning your solvent printer, for example. When talking to INX-Digital they informed me that one of the biggest issues with hazardous solvents, especially in California, is the cleaning fluid. Fortunately, today you can get cleaning fluids that can pass California’s rules.