I just finished a print shop for a coffeemachine, there will be around 1000 unit prints
I have one stupid question, and I'm kinda scared:
When I export it as cmyk it looks good on my screen but when I upload it online the colors look wayyy different.
Will this be the case when printed too?
In Illustrator, I've changed the color mode to cmyk and just 2 of the colors got a bit lighter
Don't trust on-screen representations of CMYK. Like, ever. Even the most sophisticated .pdf viewers are bad at representing CMYK colours on an RGB screen.
If you have created a proper .pdf with a proper colour profile, colours should be ok. The only ways you're ever going to be sure of how it's going to look when printed is either calibrating your monitor (requires equipment and software, and therefore an expensive solution) or experience.
Vincent is correct, you can't really get a correct representation of CMYK (subtractive color process) on an RGB screen (additive color process), especially with certain colors like green.
That said, most quality commercial printers will/should provide a printed color proof of some sort before printing the whole run. Definitely check with your printer (or have your client do it) before printing! It's a very standard request; In fact, many printers won't run the job without someone signing off on a printed proof.
If you're having them printed through an online company (much more common these days), you can still get a printed proof mailed to you, but in my experience, many of the online companies just expect you to go with whatever you see on screen. For less important jobs, this may be fine, but I wouldn't trust it.
