Printer requesting Rich Black converted to Pure Black

A content description or a (partial) screenhot of a typical pdf of those work would be very explanatory and help on how to proceed or set a correct workflow for your work. Thanks.

/* I have over 100 Photoshop PDF files that are being sent to print, each with many layers. I have converted them from RGB to CMYK and now the print shop is requesting that the rich black be converted to pure black (I'm assuming standard black). How do I do this?

Is there a way to do this to the entire document, or do I have to go layer by layer for each file? */

Assume nothing, you are already re-doing work as it is!

It is highly unusual for photographic imagery to have K only blacks. Are these "illustrations" like comics or similar?

When you converted from RGB to CMYK I am guessing that the images were flattened.

I would go back to the original RGB files if possible.

I'd convert them using two different methods and then combine them into one, taking the best from both methods. This would be recorded into an action and then batched or applied using Image Processor or Image Processor Pro scripts. If there is still interest in this I can go into more detail.

Good luck!

Go back to your RGB files and convert again to PDF, but do not convert to CMYK, stay in RGB.

Then in Acrobat Pro, select Print Production Tools > Convert Colors to do the RGB to CMYK conversión. BUT do not forget to ckeck the Preserve Black option below.

(Preserve Black: Preserves any black objects drawn in CMYK, RGB, or grayscale during conversion. This option prevents text in RGB black from being converted to rich black when converted to CMYK.)

»Is there a way to do this to the entire document, or do I have to go layer by layer for each file?«

Theoretically you could separate the RGB files to a »Custom CMYK« profile with max black generation. 

Naturally that would be a bad approach. 

What are the black elements? Type, drawings, …? 

Please post an example. 

»I have converted them from RGB to CMYK «

Converting layered RGB files to layered CMYK files can cause considerable problems and should be a very deliberate choice. 

Your printer wants the blacks to be just 100% black. When you convert from RGB to CMYK you end up with a four color mixed black. Recolor art in Illustrator is the easiest way to fix this, but this works for Illustrator not Photoshop. You posted this in the Photoshop forum. What application did the PDF documents originate in?