Opacity Vs. Transparency (In Screen Printing).

Hello! I want to show you, very briefly, about the differences in Opacity and Transparency when it comes to screen printing. (Updated note: This was originally a tutorial for a friend having errors printing out a design to be screen printed. Most of the information is still relevant, but I thought it was worth noting at the top of the article exactly WHY I had posted it.)

First, take a look at this original file. I'm going to be showing you the top part of the design, where it says, "Kitten".

Full View of the Artwork.

Here's a closer look at the Kitten.

That's at 100% opacity (on the colors palette), and it is 0% transparent (100% opacity on the transparency palette.) 

Meow!

Transparency

Now, if you find your transparency palette (Window -> Transparency), you'll see a slider that allows you to adjust the opacity and the blend mode. (Mine is in the top right corner if you want to see) If you select the part of the design you want to edit and move the slider closer towards zero, you'll notice that it makes the design more transparent and allows the artwork behind it show through. See next image.

"Kitten" at 25% Opacity in the Transparency Palette.

You can see the red gradient behind the words now. Using this adjustment, you will have the lettering print as a halftone (25% white), and the red will print as a halftone as well. (You will have a blend of red and white.) I don't recommend making designs for screen printing this way, unless your customer requests it. (You can put a copy of the same design at 100% opacity behind the transparent design so that you can still halftone the top art, but that's for another tutorial.)

Transparency is a lot of fun to play with, but for a majority of screen print customer orders, it's not necessary. It can cause troubles, such as having a lot of halftones in one area that tends to make the image muddy and messy when you print it on a shirt. It's a great setting if you don't have any elements of the design lying underneath though. Also, if you want to render a mock-up for a customer, it looks more accurate on the screen to use the transparency setting rather than the opacity, because the halftones will allow the color of the background to show through rather than bright white.

Opacity

Now find your colors palette. If it's not on your screen, it will be under Window -> Color.  I find it easiest to put the palettes near each other, but that's just me. Usually, there will be sliders to adjust colors based on what ever color mode you are in (RGB, CMYK), and there is no opacity slider for those. The adjustment can only be made for global and spot colors, so if you need to adjust the opacity, you'll need to assign your art work one of those two. (Make color swatch after you've selected the art, and double click it. There's a dropdown box that will allow you to make it a global or spot color.)

Here's a picture of the Kitten after it's been assigned a global color.

Kitten in Global Yellow

I have made the words yellow because you cannot adjust the opacity of the color white! (Actually, you can, but it won't make a visual difference. It will print the white as a halftone if you have it set as a spot color though, so be careful!) This is because when you adjust the opacity of a color instead of a transparency, it draws the image as if it were on a white background (it's called a knockout). So, as you adjust the slider closer towards 0, the image becomes more and more white.

Kitten at 50% Opacity.

Kitten at 25% Opacity.

You can see above that they get lighter and lighter. These will print as halftones of their global or spot color. Below, I've added a picture of 0% opacity:

Kitten at 0% Opacity.

If you set a part of a design at 0% opacity, it will not print at all, but it will leave a knockout in that area. (Meaning that where the letters touch the red gradient, there will be no gradient there, just empty space.)

I recommend working mostly in the opacity settings, as it seemed less likely to print with unexpected errors.

And that's the basic differences as it relates to screen printing, or at least, screen printing at my old job. There are a lot of things not covered here, such as blending mode (which kind of changes everything I just told you; all these images are using "Normal" blending mode) and how to make spot or global colors. Hopefully you'll have a better understanding of which setting does what, but if not, feel free to email me!