I am placing some Photoshop-made artwork into InDesign and exporting to PDF for print. My artwork is quite dark, and Ps's eyedropper tells me that some of my blacks are around the 90/95/95/85 mark. My printer specifies a max of 300% ink. Will the colour profile I use in InDesign (Web Coated FROGRA28) automatically convert these to 300% max equivalents? If not, what do I need to do to prevent the print from becoming way too wet?
Did your printer request FROGRA28? If so I suspect it is fine. If not then as best I can tell it does not reduce the ink low enough if their limit is 300. Some printers are higher, for example the one we use is 321 and FROGRA28 appears to meet that criteria.
How did I come to this conclusion? Easy really, I opened up a new CMYK document in photoshop made a gradient from 0,0,0,0 to 100,100,100,100. Then converted the profile to FROGRA28 and eye dropped the 100,100,100,100 area to find that it was now adding up to about 310.
As far as tricks to fix it, that forum post probably works and might even work better than this method but all I do is convert the image in photoshop to Lab profile and then convert it back to CMYK and it drops all of the colors to under 300.
I suspect another thing you could do to check is take your ID file and finalize just one of the questionable pages to a press ready PDF file based on your Printers specifications, open the PDF in Photoshop and eye-drop it to see where the darkest blacks are at after all of the processing is completely done. I think its going to be about 308 though just like I got doing it straight in photoshop.
You can also use various tools to report the coverage of a print-ready file: