I made a design in a document with CMYK color mode and exported it to PNG with transparency to send to an online service that prints it on goodies (mugs and hats on Vistaprint, if that helps).
The PNG file is in RGB color space. I prefer transparency and PNG as I don't know if their service has specialty white ink. I suspect that the conversion from a CMYK document to an RGB file and back to CMYK on print will change the colors.
I am using Adobe Illustrator CS5, mac OS Mojave 10.14.6 (yes, really, I made it work). The color settings in
Edit > Color settings for CMYK are
U.S. Web Coated (SWOP) v2 and
Edit > Assign profile shows the same profile ticked:
Working CMYK: U.S. Web Coated (SWOP) v2.
When I export the artboards to PNG, I see no options of a color profile in either dialog:
How can I export designs in CMYK color mode with transparency to minimize color mismatch during printing?