Developing a treatment plan: The main challenge has been finding the right consolidant, one that will improve the leather’s strength so subsequent repairs will hold. I have plenty of experience working on leather artifacts, and know what the limited options are when the leather is this degraded. Klucel G works well in the short-term (it has good penetration and effectively consolidates the powdery surface) but is relatively weak, and is known to have a short lifespan of usefulness. What’s more, Klucel is fairly brittle and has shown unsatisfactory long-term ageing characteristics, particularly in an acidic environment such as that encountered with deteriorated leather (e.g. in the presence of sulfuric acid from absorption of sulfur dioxide in the atmosphere).
I recently began using Klucel/SC6000 mixture with good results in terms of improved strength and flexibility; the problem is that it tends to sit on the surface and does not penetrate into the leather structure very well. I’ve also used Pliantex in the past with a very good outcome. Despite the nasty smell of the solvents, it has excellent penetration and imparts sufficient strength and improved flexibility to the leather. Unfortunately, this product has been discontinued and is no longer available! (We happen to have a small supply left over from a similar treatment we did some years back–possibly just enough to last through this project.)
This is a dilemma we all struggle with at some point in our careers as conservators. It is understood that any consolidant introduced into a porous material such as leather, is for all intents and purposes, not reversible. It would be nearly impossible to extract the consolidating agent from the porous material completely. And why would you ever want to, as long the material is stable and is not causing any harm or threatening the future stability of the object in question? There are really only two choices: 1) either to do nothing at all and let the object continue down the path of deterioration and eventually cease to exist, or 2) do something that we’ve been taught to avoid, something that defies our ethical sensibilities—that is, something not readily reversible—and by this intervention, ultimately allow the object to survive for future generations to enjoy.
A description of the actual treatment (so far) is coming soon…