To trim or not to trim. Is that the question?
A book conservator deals with main ethical considerations. Sometimes because of the customer desire's, and most of the time seeking an equilibrium between preservation and functionality. To top it up, we expect the result to be pleasant as well: not too new, not too worn; most original, but not too weak...
Rare is the case when we find a salomonic solution that satisfies all the requirements.
I guess a conservator is not the type who cuts the gordian knot, but rather one who tries to unlock it no matter how painful that is!
Wrinkles and folds are a usual damage in documents made of paper, cloth or parchment. The common way to restablish these supports to its original condition is by pressure: under weights or in a press.
When the paper has a relief which must be preserved, it is then not possible to use pressure, as it would smash this relief.
Flattening under tension may be an interesting alternative on certain occasions or when a selective flattened is needed. It takes advantage of the natural shrinkage of the paper when going from wet to dry, so that the tension is given by the same paper.