Why We Always Sep in Channels

“You sep in channels? Why do you sep in channels?” When I hear this, I find myself wondering, “Who in the hell told these people to sep in layers?!”

To be clear, I am not a person who thinks there’s only one way to skin a cat. We all know there are many ways to get the job done.

Having said that, I refrain from ever telling anyone they’re, “doing it wrong,” but in this case, if you’re sepping in layers…you’re doing it wrong!

If You Sep in Layers, You’re Doing it Wrong!

Now, unfortunately, you’ve been led down a path of unrighteousness by a foul and menacing gremlin-like turd but I’m here to help. Here’s why we don’t sep images in layers, ever…as in never ever ever ever!

It’s Faster to Sep in Channels

Channels are set up to work with black and white only. This is great for screen-printers because we can quickly look at each of our channels in a manner representative of how we’ll see it on a piece of film – as an emulsion up film positive.

working in channels

When you sep in channels, to view how a channel will print, you simply need to select it.

Yes, you can do this with layers but the emphasis here is on the word “quickly”. We need to work quickly in a production environment. The extra steps it takes to make/view layers-based seps as a simple black on white image is too much. It’s definitely enough to justify finding a better workflow.

To boot, messing around with the layer’s mode is also a trap many new color separators fall into as well. The layer’s mode has no effect what-so-ever on how much ink will go down. It simply affects what you see on your monitor.

Since our final output is not your monitor, this should be avoided at all costs. In fact, if you’re messing with the layer’s mode while separating in layers, you’re doing it seriously wrong.

Channels Are Made For Color Separations

You’ll notice the composite channels are indeed channels. These are your CMYK or RGB channels that, when put together, comprise what you see as your final image.

If the program’s putting together the image in channels, shouldn’t you?


The composite channels used by Photoshop

Simply put, channels exist to build images based on color information. A group of base colors (CMYK, RGB) mix to varying degree in order to create a wider color palette.

This is the same principle as simulated process color separations. The only difference is that we’re using the colors we feel are best suited for each individual image we work on.

And as mentioned before, being able to quickly review how individual channels look in both a black and white state as well as a composite colored state is pretty much tailor made to suit screen-printers. Lucky us!

The Pros Sep in Channels

It’s worth noting what the majority of professionals in any industry do along with how they do it. They are professionals for a reason.

And in the case of color separators, I’ve worked in this field at/with some of the industry’s best companies for 15 years now and every single top-of-the-game color separator I know separates in channels.

…every single top-of-the-game color separator I know separates in channels.

This includes everyone I’ve ever worked with, be it at the United States’ number 1 licensor of Rock and Roll and entertainment apparel or at one of the States’ highest volume screen-printers (listed by Impressions Magazine).

Literally, there has not been a single professional color separator I’ve ever encountered who separates in layers, not one in 15 years.

Think about that. These are the guys who sep the stuff you look at wondering how they did it—channels…all of ’em.

It’s also worthy to note that most every automated sep software plug-in for Photoshop also seps in channels. I say “most” because I’ve not worked with them all but the ones I’ve seen all operate within channels.

Output Layers vs Output Channels

There could be an argument over whether or not your shop could be considered a proper screen-printing shop based on whether or not your shop employed a RIP system. Either way, when it comes to printing films from layers-based color separations, the RIP isn’t going to save you any time.

Turn off each unwanted layer, hit print, turn that off, turn on your next layer and print that, etc. In the name of efficiency…bitch, please!

Once you’re done with a properly formatted simulated process color separation, it gets output in one fell swoop. All of the individual colors are told to print at once and the RIP handles the angle, lpi, and dot shape. You don’t even need to input that info into Illustrator.

Output dialog - sep in channels

Print your seps all at the same time from Illustrator.

Photoshop was not made to print things out. Yes, it’s possible to print via Photoshop but I wouldn’t suggest doing it unless you had a book to read while you wait for it to process the queue.

I throw to the RIP from Illustrator and my first piece of film is already half-printed while you’re still waiting for Photoshop to process what you’ve told it to print.

This goes without mentioning that I’m done with that job now and can move onto something else while you’re waiting for Photoshop to print your film. By all means, if you’re the type of person who likes to stand in lines…

Of course, printing colors separations placed into Illustrator is only an option if you’ve made your color separations in channels. Can’t do it this way if you’ve sepped to layers.

About That Cat…

There are a handful more reasons that could be used to illustrate why separating in channels is the best practice but as mentioned before, there’s more than one way to skin a cat. However you choose to skin yours (seriously, where did this saying come from) is up to you. If you like doing things the long way, by all means.

But, while you’re off messing around trying to skin a cat with a dull spoon, I have a nice sharp knife if you ever need to borrow it.

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