Screen Printing Wet on Wet with Plastisol Inks:
How to get the best prints without flashing between colors
You can produce quality screen printed shirts, hoodies, long sleeve t-shirts and other garments by printing wet plastisol ink on more wet plastisol ink. This method is called wet on wet printing. Employing this technique means you will not be flashing between colors but silk screening one plastisol color on top of the next. There are a lot of advantages of wet on wet and not using a spot dryer between each color.
It is important to realize that wet on wet is not always the best. For example, screen printing a vibrant color on a dark shirt with an underbase should be printed wet on wet, or using specialty inks like glitter are best printed after flashing (or spot curing) your print.
When to print a screen print job wet on wet
The wet on wet printing method works best with designs where there is little (or limited) overlap of colors or the number and/or size of large areas of ink are limited. Having your graphic artist understand this helps when you are on press.
Try using more of the negative space, or the t-shirt color in the design. You can still print wet on wet for designs where colors touch, but it can get tricky, so keep it to a minimum. When it comes to designs with bright colors on dark garments, consider alternatives that can achieve the same effect, such as using a different color, printing with a halftone, or try printing the color without an underbase
Choosing high opacity inks for wet on wet printing makes a huge difference. While they do cost more, these high quality screen printing inks provide significant savings in labor and speed up production.
Getting the right screen printing frame for wet on wet printing
Screen frame mesh count selection: Wet on wet printing requires a higher mesh count than print flash printing does. Think 180 or 230 instead of 110 or 125. Thinner mesh counts deposit less plastisol ink on the garment. Putting less ink on your shirt lessens the chance that the ink will smear or picked up (stick of the print side) on the other screens. Just try something with a slightly higher mesh count than you typically use and see how it works.
Screen tension: This is something you should check consistently. Higher screen tension means that the surface will bounce back quicker once the squeegee passes. Quicker recovery of your surface is another way of reducing the chance the ink has to smear and run. For wet on wet, the recommended screen tension is 25 newtons (N/cm2) or higher. Pro tip: each screen on a job should be within 2 newtons of the others.
Emulsion over mesh (EOM): This is an often ignored factor of the screen printing and screen making process that makes a big difference on the final print, whether you are doing wet on wet or not. Applying less emulsion means a thinner stencil. Thinner stencils deposit less on the shirt, which decreases the chance that the ink will smear.
Are you picking up on the theme here? We are trying to control the ink through each of these variables. Perhaps try a 1+1 coat (one emulsion coat per side per screen). To get slightly technical, try for a 20% EOM by calculating 20% of the thickness of the fabric you are printing on, in microns. The best shops have a micron meter to truly dial in the amount of emulsion. Its important to note that when coating screen printing frames with liquid emulsion by hand, there will be some various in EOM from screen to screen (and maybe from spot to spot on the same screen).
Screen Off-Contact: This is the distance between the underside of the screen and the surface of the platen. With a garment loaded on the platen, the thickness of the material changes that off-contact. You should become familiar enough with your machine to be able to adjust the off-contact. The goal in wet on wet is to control the ink while speeding up the process, it would make sense that changing the off-contact for printing on a sweatshirt versus a super thin tank top or even a bandana would be important. The thicker the garment, the higher the off-contact you should use. About the thickness of a quarter or a paint stick should suffice for t-shirts. If you are having trouble with ink smearing, try increasing the off-contact.
The best plastisol screen printing ink for wet on wet printing
When printing wet on wet, you want thinner, creamier plastisol ink. Vigorously stir the ink before loading it into your screen. The best way to do this is with a drill and mixer or an automatic ink mixer. For a video demonstration on this, watch our video on Proper Screen Printing Plastisol Ink Preparation. In some cases it may be necessary to thin the ink further with some curable reducer. If you do decide to try curable reducer, make sure to start with a small, measured amount (about 2% by weight to start with) to test it out.
Actually printing wet on wet on a t-shirt and other garments
Screen print order: Most of us have been taught from the very beginning to print in the order of the lightest color to the darkest color. Other things to consider when deciding the printing order are:
- Print smaller areas first. There will be less ink on the garment to potentially be picked up by subsequent screens.
- Print details last. The details are what captures the viewer’s attention. Printing them last will keep the details crisp and opaque by ensuring that there is no chance for the other colors to blend or muddle them.
Squeegee use: As with any other screen printing methods, squeegee technique is important. When printing wet on wet, pressing too hard can cause the ink to go right through the fabric, resulting in a loss in opacity. With wet on wet printing we are working hard through all the small details to combat problems of bleeding, opacity, and screen buildup, understanding how to select and use the right squeegee the right way is so important. Things we need to consider are durometer, pressure, and the angle. Read our blog Choosing the Right Squeegee to help you find the right silk screen squeegee for you.
- Durometer: In general, you will probably want to use one with a higher (harder) durometer since you are working with a higher mesh count screen and are wanting a thinner ink deposit. Harder blades are also better for fine details. Use a 70 or 80 durometer.
- Pressure: You need just enough pressure to push the ink through the screen completely until it rests gently on the surface of the garment. Your squeegee shouldn’t necessarily be bent in the shape of the letter “L.” Too much pressure can cause problems and drive the ink into the shirt.
- Angle: The squeegee should be angled more vertically than horizontally. Shoot for about an 80 degree angle.
The important thing to know is that the squeegee you choose will depend on the look you are hoping to achieve. Keep your squeegee sharp and sharpen it when necessary!
Now you are ready to try wet on wet printing on your own. Each factor we have discussed is important in printing quality images quickly. Remember that they may take some tweaking with your particular set-up to really get the hang of it. Make sure the design you’re printing is one that makes sense for printing wet on wet, and select and set your materials and equipment to best control the ink. Paying attention to all these factors and printing in the best order will help avoid buildup on screens, which will eventually cause blurred, rough edges instead of clean and crisp lines in your prints. Now try some wet on wet printing on your own and be amazed at what you can produce!