At what temperature can I safely iron the fabric bookmarks in the volumes of the Bibliothèque de la Pléiade?

Question

I recently acquired a volume from the famous Bibliothèque de la Pléiade from an antiquarian bookseller. These volumes always have two fabric bookmarks and as you can see from the image below, the bookmarks in this volume are creased.

I would like to iron the bookmarks but I have no idea what type of fabric Gallimard uses for them. Hence, I don't know at which temperature I can safely iron them. Can anybody give advice?

Update: Since the age of the book may be relevant to the materials used for the bookmark (i.e. synthetic or not), I want to add that the volume in question is Albert Camus: Théâtre - récits - nouvelles, edited by Roger Quilliot. Bibliothèque de la Pléiade. Gallimard, 1967. (This volume is not to be confused with Théâtre - Récits et nouvelles - Essais in two volumes, published in 1980.)

Answer 1

I don’t know what fabric the ribbons are made from, but there are a number of precautions you can take to minimise risk of damaging the ribbons:

• Don’t iron directly onto the fabric, always use an intervening layer of a cotton or linen fabric. This much reduces the risk of melting or scorching the ribbons.

• Use moist heat. I probably wouldn’t use an iron at all, but a steamer that doesn’t actually need to make contact. I have a couple of different types: this kind intended for cleaning and this kind intended for dewrinkling clothes. (Neither of these is the actual models I have, but you get the idea). The steam will help to relax the creases out of the ribbon better than heat alone, but I would recommend then pressing the ribbon between flat heavy object until fully cooled and not putting between you’d book pages until utterly dry.

• In the absence of a steamer you can iron the ribbon between dampened cloths.

Needless to say, steam and damp air are no friends to previous editions and you should take steps to adequately protect the book during these operations.

Answer 2

What I have done so far is the following:

• To be on the safe side, I used the iron at its lowest temperature, which is suitable for synthetic fabrics for synthetic fabrics (even though I doubt that the material is synthetic). This does not lead to a perfectly flat bookmark, but at least it remains flat; the book's gravity (2200 pages of bible paper) can do the rest.
• I flattened centimetre by centimetre with my fingers, held the fabric in place using the forefinger and middle finger and put the tip of the iron on the piece of fabric between my fingers. The reason for this is that this narrow strip (just 4 millimetres wide) is not simply creased but folded and I want to verify that it remains flat until the iron is actually on it.
• I did not use steam for two reasons: (1) I'm rather reluctant to use steam near Bible paper, which is extremely thin, and (2) the steam function on my iron no longer works very well.
• For the part near the spine, I needed to put the book on its spine (between two other objects to hold it in that position) in order to iron the last 1.5 - 2 cms of the bookmark. (This is where steam would be even riskier.)

You can see the result below. It's not perfect, but as I said above, the book's gravity can do the rest.