ok... well obviously all art isn't done with vector tools, so why would this Tshirt printer only accept .eps and .ai? What If I wanted to hand draw something and put it on the shirt, but maybe mix it with vector stuff?
and in my original post I meant I "use PS and OWN AI."
anyways here's a sign for work... I designed it for an 11x14 sign holder, but I might spread it out a little and just print to 11x17 and tape it onto the holder from behind. I made this in PS... would there be any advantage to doing something like this w/ Illustrator??
I dunno if I should color the books in at the bottom or leave as is...
Here's a few quick notes:
And just because I know you wanna crucify me right now for how shitty those notes were added in PS, here's a quick AI mockup inspired by your basic layout and design, just given a little more room to breathe. I don't think this is the be all end all, or a finishing point (you could start with this basic layout and begin to add as much or as little decorative flourish from here as you'd wish), or even think it's very amazing at all. I just thought it might be useful for you to see another person's take on the subject.
I hope you understand I mean these critiques with the best intentions, and hope you keep up the good work. Super rad that you're working at a book store too. That sounds perfect for a designer.
As for your question as to why a print shop might request a t-shirt design as an AI or EPS file (EPS is just another type of open source sorta vector file, any vector program can output or open it).. My guess would be that this t-shirt printer is using a silk screen process, which is usually done with a limited set of colors, each color getting its own plate.
You can see the basic process in this crappy internet jpg:
So as you can see, the screen is a completely binary process: either it's letting ink through, or it is not. There's no room for gradients, grunge effects, transparency, etc. That is probably why they want flat color vector files. So they can separate out each color and make a screen of it. They also want to make the screen with a very high resolution file, which of course a vector file is basically unlimited resolution, so they can have nice crisp separation of colors.
That said, even with simple 2 color screen printing, you can still simulate shading through effects like half-tone patterns, and you can make an overall gradient with the ink you lay down:
And, as with most things in this world, there's probably a lot more I don't know about the process, and as such probably some even cooler techniques that I don't even know about! But, from my limited experience making t-shirts, that's what I have encountered, and I'm willing to guess that's why this shop made that request of you.
Cheers.