You have found the custom printing vendor‘s FTP site and you’re about to send your files to press. With bated breath, you hope that you caught all the errors, formatted all the files correctly, and didn’t make any mistakes that will be expensive to fix. Before you push the send button, here are some things to check.
Check the Fonts and Links
Make sure that you are using the proper fonts. Specifically, use the bold or italic font for a particular type family. Don’t use the (pseudo)-bold or (pseudo)-italic button to alter the type.
In InDesign, you can go to the “Type” menu, then go to “Find Font,” and you will see a list of all the fonts you are using, including the font family, weight, and whether the type is condensed or expanded (for example, Helvetica Light Condensed). You can also see whether the typeface is Adobe Type 1, OpenType, or TrueType. (Some commercial printers I’ve worked with have had problems with TrueType used on a Mac, so check with your custom printing provider before sending a file that uses TrueType fonts.) If you don’t like what you see in the list of fonts, you can do a “search and replace” from this menu item to change fonts, either one instance at a time or globally.
Also, check “Links” under the “Window” menu. It will show you any TIFF or EPS images you have placed in your InDesign art file. You can see the color space (RGB or CMYK, for instance), format (such as TIFF) and page number on which the image appears. If you have altered the original Photoshop image file, you can also update the links to replace the old version with the new version.
Color Space
Speaking of color space, make sure you have changed the images from the RGB color space to the CMYK color space if you will produce the custom printing job on an offset or digital press. You would only use RGB for a Web document that would appear on a computer monitor. As mentioned before, the color space is also noted in the “Links” window.
Bleeds
Make sure you pull the picture boxes 1/8” beyond the trim of your print job in InDesign (or any similar program). This part of the image must extend beyond the “trim” line of your document page, so your commercial printer can cut this portion away in the bindery to give the impression that the photo bleeds off the page.
Package
InDesign calls the collection of fonts, images, and art files their “Package” function. This function can be found under the “File” menu. Quark has a similar attribute called “Collect for Output,” also under the “File” menu. Both programs allow you to collect in one folder all that you will need to send to the custom printing supplier.
Read more at https://www.printindustry.com/blog/2011/12/custom-printing-preparing-your-printing-job-for-commercial-printers/
