What do they call a strip of paper made to protect the endpapers of books during the bookbinding?

Question

I understand if this sounds like an odd question, so please allow me to explain.

I am reading an entry in a French dictionary and translating it into English. This entry is “sauvegarde.” In a general context, this term is translated as “safeguard,” “protection,” or even “conservation.” However, in the context of bookbinding, the definition essentially says, “Strip of paper made to protect the endpapers of books during the bookbinding.”

Now, my knowledge of bookbinding is sorely lacking, but I am reasonably confident that “safeguard” is not the word that goes with that definition. My research indicates that this strip of paper might be called “waste sheet” or “flyleaf,” but I am not entirely sure.

What is the word that matches the above definition?

Addendum

I have some information to add that should clarify things.

I found a website that gives an expanded definition of “sauvegarde” in the context of bookbinding. This definition essentially says, “It is a strip of paper the length of the volume, that one folds in half and that one sews before the endsheet at the beginning and after the endsheet at the end of each volume; they are used to protect the endsheets: one removes them before finishing the bookbinding and at the moment of gluing the endsheets on the cardboard.”

Reference URL: https://www.moulinduverger.com/reliure-manuelle/lexique-sauvegarde.php

In addition, for those of you who are not familiar with the parts of a book, I have found a website that does a good job explaining them. I will provide the link below.

Reference URL: https://bookprinting.com/resources/parts-of-a-book

Answer 1

Based on the citations below the best translation for "sauvegarde" is "waste sheet" based on matching the description you have given to description of waste sheet in the bookbinding process.

According to the Bookbinding and the Conservation of Books A Dictionary of Descriptive Terminology

Your description:

“It is a strip of paper the length of the volume, that one folds in half and that one sews before the endsheet at the beginning and after the endsheet at the end of each volume; they are used to protect the endsheets: one removes them before finishing the bookbinding and at the moment of gluing the endsheets on the cardboard.”

matches the description for the definition of the term "waste sheet"

1. A sheet of paper tipped to the outside over the permanent endpaper to prevent it from becoming damaged or soiled during the binding of the book. Special instructions on binding the book may also be written on this sheet. Originally, the waste sheet was printed with an abbreviated title so that the publication could be identified. The so-called printed waste sheet is known as the half-title paper and is always found in books of any pretension to high quality.

Also - From the article on BPG Endpapers:

Waste sheets protect the pastedowns or linen stubs during binding operations. They can be removed before pasting down, or adhered underneath the visible board sheet.

BPG Endpapers - Terminology

Also -
BPG Endpapers - Made Endpapers

If the book was small, the first white flyleaf was left as a waste sheet to be torn off at the time of pasting down the cover lining leaf of the endpaper.

Searching the article for the words "waste sheet" will demonstrate that different bookbinding practices treat the waste sheet in different ways.