How to flatten PDF forms with Preview in OS X

How to flatten PDF forms with Preview in OS X

If you need to save a filled-out PDF form so the content is no longer editable, you can do so with Preview in OS X.

The PDF format is handy as a cross-platform approach to preserving
document layout and structure; PDFs are commonly used for electronic
forms with editable fields for you to fill in data. While this is
convenient, if you have a PDF form you are managing, you may run into an
issue if you want to save the PDF’s entered data in a static form that
can no longer be edited.

Doing this is called “flattening” a document, and is commonly applied
to any file type that contains multiple elements to present a final
rendered product. For example, a Photoshop image may have numerous
layers to it so each layer can be edited separately by the artist.
Flattening the layers combines them into a single layer, making them no
longer editable independently.

These fields are editable simply by clicking them,
 and to prevent them
from being edited you will need
 to “flatten” the PDF (click for larger

Similarly, an editable field in a PDF is simply another layer that
the PDF format supports, and they can be flattened to make any entered
contents static. However, if you add data to a PDF form in Apple’s
Preview program (the default PDF reader in OS X), you may find no
explicit option to flatten the PDF. If you save the PDF or duplicate it
to another document, or use the “Export” option in the File menu, the
fields will continue to be editable when you next open the document.

Despite this apparent limitation, OS X does have a feature that will
properly flatten a PDF in Preview. Instead of using standard file saving
and exporting features supported in the program, use the global “Print
to PDF” service in OS X. This global service will take any document in
the form that is sent to the printer, and save it as a PDF instead.
Since the printer cannot handle multiple layers, this service will
flatten all contents to a basic PDF document.

To do this, simply press Command-P or choose the print option from
the File menu. Then select “Save as PDF” from the PDF menu at the
bottom-left of the print dialog box. When finished, the resulting
document will no longer be editable.


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