Printing with white ink can be deceptively difficult – here are some tips to help you out!
There are several reasons white ink is notoriously tricky: It has more pigment than darker inks, so it’s thicker and more difficult to work with. You need to lay down a thicker layer of ink to create an opaque white print on a dark substrate. There are a lot of different white inks on the market, and using the wrong white ink can have a negative impact on your print.
While screen printers differ on their approach to printing with white ink on dark colors, here is our guide to printing with white ink.
Choose the Right White for the Job
Finding the right white ink can be more difficult than it seems, as there are a surprising amount of white inks on the market. While it might be tempting to pick one white for your shop and stick with it for all jobs, you’ll have much better success with your white prints if you pick the right ink for your substrate. White ink options include:
Cotton whites. As the name suggests, cotton white ink is made for printing on substrates that are 100 percent cotton, nylon or other substrates that aren’t subject to color bleeding during curing. Cotton whites are extremely easy to print with, and they leave behind a good finish.
Low-bleed whites. Low-bleed inks are designed for use on polyester or other synthetic fabrics whose dyes will bleed and stain the white ink during curing. Some printers are tempted to use a low-bleed white for all of their white printing, but low-bleed whites aren’t always the best inks: They can have a rougher feel, and the chemicals within the ink can affect the dyes in substrates, leading to a faded ring around the white ink referred to as “ghosting.”
Polyester whites. Polyester whites are a higher grade low-bleed white designed specifically for polyester printing. They are expensive and have a high viscosity that makes them more difficult to work with.
Mixing whites. Mixing whites are intended to be mixed with other inks for color matching, though some printers will use their mixing white as a white underbase.
On top of the type of white ink you choose, you’ll also have to find a brand that you prefer. Different white inks have different levels of opacity, different levels of bleed resistance, different flash-curing characteristics and different hand feels. Choosing which brand of white ink to print with generally comes down to personal preference, and a shop’s preferred white usually must be found through trial and error.
Production Techniques for Screen Printing with White Ink
Once you have found the right white ink for the job in your preferred ink brand, printing with white ink still takes some special care. First, because white inks have more pigment and a higher viscosity, you’ll want to do what you can to make the ink easier to work with. Because you’ll probably want your white print to be opaque, you’ll have to make sure you’re laying down a thicker print. Finally, you will have to alter your curing process because white ink doesn’t always cure like other inks.
Here are some steps you’ll want to take when printing with white inks:
Use the right mesh count. Because white ink is thicker, and because you want to lay down a thicker deposit of it, you will have to use a lower mesh count screens. Printers vary as to what mesh count they prefer to use with white inks, but the mesh count should be in the 110 to 200 range. Whatever your mesh count, make sure your screen is taut to allow the ink to sheer cleanly away from the substrate during printing.
Make a thicker stencil. When you print, the thickness of your stencil determines how much ink is left behind on your substrate. With white ink, make sure your stencil is thick enough. Use the rounded side of a scoop coater when putting emulsion on your screen, consider adding a second coat on the substrate side of the screen and always dry screen vertically, with the substrate side of the screen down.
Increase your off-contact. A slightly greater off-contact distance will help you to lay down a thicker ink deposit, and it will help your screen clear your print more smoothly. Try using an off-contact distance of 1/8 inch when printing with white ink.
Employ proper squeegee technique. A rapid, firm squeegee stroke will lay down a thick, precise white print. Don’t be tempted to press harder to lay down more ink. Let your squeegee do the work.
Cure white prints longer. White ink can reflect the heat of your curing unit. Because of that, and because you generally lay down a thicker white print, white prints take longer to cure. Slow down the speed of your conveyor dryer to allow your white ink enough time to cure. Test the final temperature of your ink as it comes off of your curing unit to make sure it has reached the curing temperature listed by the manufacturer.
White ink does have a learning curve, and it can be surprisingly frustrating for new and seasoned screen printers alike. By choosing the right white inks and slightly modifying your production process, you can erase the frustration and turn out perfect white screen prints every time.
Looking for some more tips on choosing and preparing your ink? Check out these blogs: