Screen printing can also be used to decorate many plastic substrates, like signs, containers and point-of-purchase (POP) displays.
There are plenty of benefits to expanding your screen printing offerings to include plastic substrates. You probably won’t need much in the way of additional equipment to get started, so it can be a cost-effective way to attract new orders. Many promotional items are made from plastic – items that should appeal to your current customer base. For example, if you provide screen printed shirts for a corporate client, that same client may be interested in screen printed plastic graphics for their next trade show. Plastic products can increase your opportunities to upsell and cross-sell, giving your revenue a boost. While there may be a learning curve to screen printing on plastic, it’s much easier to remove mistakes from most plastic surfaces compared to fabric.
(L-R) Polyethylene terephthalate (PET) bottles, polypropylene (PP) bags, and
polystyrene (PS) containers help illustrate the wide variety of plastic products available
Just like with fabric, plastic comes in so many varieties that the amount of options can seem overwhelming. And like fabric, different kinds of plastic require different screen printing considerations, so it’s very important to familiarize yourself with the material you’re printing on. You’ll probably recognize some of the different groups of plastic:
Those are only a few of the different groups of plastic. While most plastic products are synthetic and oil-based, there are also “bioplastics” made from organic materials. Keep in mind that plastic materials can vary widely even within the same group, so you really have to pay close attention to the properties of your substrate to make sure you get good results. Even a plastic substrate that looks and feels familiar to you may respond to printing in vastly different ways than you’re used to. Because plastic properties vary so much, thorough testing is critical before you begin production.
It’s very important to consult your ink manufacturer to make sure you choose the right ink for the job. Your ink manufacturer should also be able to suggest any additives you might need to ensure your print properly adheres to the substrate. It’s a good idea to use air-dry inks for most plastic applications, instead of inks that cure with heat. Extreme heat can warp or melt many plastic substrates, so it’s usually best to keep them away from flash cures and conveyor dryers (though this depends on the item being printed).
If you’re printing a multicolor job with air-dry ink, you’ll have to let each layer dry between colors. Air-dry ink does exactly what its name says, so you can’t leave it sitting in your screens like you might with plastisol. It’s best to reclaim your screens quickly after printing so the ink doesn’t have a chance to dry in the screen. Like with any other print job, your choice of ink will determine the mesh count of the screens you use and the off-contact distance you’ll need. Air-dry inks tend to be on the thin side, so you’ll likely need to print them through higher mesh count screens. Before printing, make sure the surface of your substrate is clean, dry and free from any scratches or defects. And as with any new substrate, practice makes perfect!
While your current screen printing press should be suitable for most plastic applications, you may need to invest in a few additional supplies (besides ink). One of the most common plastic items you’ll be asked to screen print are signs. Make sure you have pallets and screens large enough to accommodate common sign sizes. A vacuum pallet is a good option for keeping flat substrates like signs and posters in place during printing.
With just a small investment in supplies and time to tackle the learning curve, you can adapt your current screen printing setup to handle printing on a variety of plastic substrates. Turning these promotional items into a lucrative source of business should come easily, as they’ll help you attract both new customers and new business from existing customers looking to enhance their branding.
Looking for some more tips on printing other substrates besides shirts? Check out these blog posts: