Screen Printing Underbase, 9 Tips
Screen Printing an underbase, can be challenging. Here I like to share with you some tips, how to screen print a nice crisp underbase.
Screen printing Mesh
Check what mesh count you use, very often people use a standard 48 (110) Mesh as under base. But this depending on your ink viscosity, if your white ink, is more liquid, why not try a finer mesh. Did you ever consider an S-Mesh, as it has a wider screen opening, and you get more ink on the T-Shirt.
Screen printing Ink
What is the background color to cover? If you have a dark color shirt, like black and you would need a bright white. You would need for sure an opaque white. But if you have semi-dark shirt colors. A semi-opaque white could do the job. Check out, the background color first, and then choose the right printing color.
Emulsion plays a big role in printing a nice underbase. You like to have an EOM (Emulsion over Mesh) from 10%. Not too high and not too low.
The goal is, to lay down a nice even layer as underbase on the garment, and a 10% EOM will do this for you.
The right Squeegee
The squeegee you use. A softer squeegee will deposit more ink than a high durometer squeegee. And consider a round edge squeegee, for water based inks. A round edge squeegee will deposit more ink again.
The amount of pressure
Don’t force the ink through the mesh. The very best is to print with enough pressure. Just to shear off the ink and clear the screen, leaving the ink on top of, rather than pushed through, the garment.
Important! The ink should stay on top of the garment and NOT penetrate the garment. If you print the underbase and you see white, when you look from inside, you know, the pressure is too high!
Squeegee speed, is important to print a nice white underbase. Water-based ink should be printed fast. You like to pump the ink through the mesh.
Off-Contact, place a big role too. That the ink stays nicely on top of the garment. 1 mm of off contact should be fine, but be sure, the off contact is all over the screen the same.
Mesh, the mesh should have at least 20Newtons. And should have min. 20new all over. Not that one corner has a different newton meter reading than the other. This will give you a result of uneven white coverage.
Choke the screen printing underbase
If you have some registration problem. And your screen printing press has not a butt-to-butt registration. Take into consideration to choke the underbase a little. Now the top colors will be covered easily by the underbase. But be aware, do not choke too much!
If you consider all 9 Points, it will be easy for you to print a nice soft underbase. Screen printing is not difficult, if you’re considering this basic tips.
After printing the underbase
Do not flash too much your underbase, you just like to gel the ink. Too much heat, on the underbase can cause more problems afterward. Get the flash cure temperature right and the index time off turning your table. Many times I have seen over flashing the underbase. If the screen printing pallets heat up too much during production, the subsequently printed inks can dry more quickly in the screen. Especially water-based inks are very sensitive to it. you like to keep the temperature of your pallets low as possible. And the only way to check this is with a temperature gun. With this Gun, you can monitor your platen temperature and assure, that you keep the platen heat low as possible. This saves you many headaches in production.