A couple of years ago we talked about printing with air-dry inks here on the blog, and today we want to revisit that topic. More specifically, printing on plastic substrates. The benefits of adding plastic printing to your offerings far outweigh the learning curve that’s easily overcome with air-dry inks/plastic printing. The great thing about plastics printing is, if you’re already an established business with a decently-sized client base, you just have to offer it to them. If your existing customers have already been interested in other specialty printing techniques, maybe they want to grow their promotional efforts with poly bags for trade shows, or giveaways, yard signs, frisbees etc. Many printers will tell you they’ve gotten more business since telling their customers that they offer plastic printing services. You get the idea. Another thing to mention with plastic printing is that it’s much easier to fix mistakes on most plastic surfaces compared to fabric.
Why do you have to use air-dry inks for plastic substrates? Well, the answer to that is in the question. Because extreme heat can warp or melt plastic, it’s best to keep them away from flash units or conveyor dryers. Air-dry inks do exactly that, air dry; meaning you’ll have to let each color dry between prints if you’re doing a multi-colored job. Remember that because the inks air dry, you should reclaim your screen(s) as quickly as possible after a job to keep the ink from curing onto your screen. It’s also super important to refer to your ink manufacturers suggestions when choosing the right ink for the job. They will also be able to suggest any additives you might need to ensure your ink properly cures and adheres to your substrate. The ColorFX air dry ink products that we carry also include a retarder and reducer. Just like any other print job, the ink that you use will determine what mesh count your screen(s) should be. In cases where you’re printing on plastic with air-dry inks, you want to start with a higher mesh count, 280 or higher as most air-dry inks are a stark contrast versus the consistency of your conventional plastisol. Printing on higher mesh count screens help ensure your ink doesn’t have a chance to fall through and ruin your printing.
Before you start printing, make sure the substrate you’re working with has been thoroughly cleaned and cleared of any dust, lint or scratches. In most, if not all cases, the screen printing press you currently have will be suitable for most plastic applications. However, you may need to invest in some additional supplies other than the ink. Due to its promotional value, signs of various sizes are one of the most popular jobs you may get, so make sure you have pallets large enough to handle common sign sizes. You might want to invest in a vacuum pallet to ensure any flat substrates like signs and posters stay where they’re supposed to while printing. Because items printed with air-dry inks must be laid out to fuller cure, be aware of where you will store these items while they dry. If you’re printing yard signs for example, you may want have some sort of drying rack set up so that you’re not taking up too much space in your shop.
Mike Napurano of Novoworks Color Imaging in Plano, Texas created a custom platen for frisbees, that's essentially "friction fitted"; keeping them secure while printing.
Much like t-shirts, plastic comes in so many varieties and options that it can quickly become overwhelming. Additionally, like t-shirts, different plastics require different printing considerations, so it’s quite important to know what material you’re printing on. Here are some of the most common groups of plastic and their applications:
- Polypropylene (PP) – common uses include boxes, bags, posters and banners
- Polycarbonate (PC) – common uses include CDs, DVDs, bottles, lenses, signs and displays
- Polyethylene terephthalate (PET) – common uses include bottles, backlit displays and signs
Polystyrene (PS) – common uses include food containers, foam containers and ceiling tiles Polyvinyl chloride (PVC) – common uses include credit cards, gift cards, signs, and construction applications
In addition to the most common synthetic and oil-based plastic products, there’s also “bioplastics” which are made from organic materials. Plastic materials can vary widely even within the same category, so be sure to pay attention to the properties of the substrate you’re working with before you actually print. Again, because the properties of plastic vary so much, thorough testing is crucial before beginning production.
With a relatively small upfront investment in supplies and a little bit of time to get the hang of things, you can adapt your existing equipment and production flow to handle a variety of plastic substrates. This can easily become a lucrative source of business as this can attract new customers and add additional business to your existing customers looking to increase their promotional efforts.