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…
Hi Irena,
This is great. Thank you for your tips. I have signed up immediately to follow
Regarding this comment: “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.”
We have been struggling with the truth of reversibility on B72 and MSA products. I had long conversations recently with manufacturing technicians because we had to justify not using a reversible project on a museum piece for similar reasons, but in the paint-on-wood area. Low and behold, they admitted that they cannot guarantee reversibility after several month due to amalgamation of the products with the paint on the furniture. (I never asked about paintings, as that is not our area of expertise.) I sometimes wonder about reversibility, as this has come up several times, and the dilemma in past has been exactly as you described. We play “by the rules” but not this time, for many reasons. I also had a discussion with a European conservator who said that this is not a hard rule in most of Europe.
When it goes on our website I will send it to you if you are interested.
Kate Powell, MPF Conservation
Kate: Thanks for your comment. I would definitely be interested in the results of your painted wood project, so please do send it to me when completed. I guess the issue of consolidant reversibility is a conundrum many of us have to struggle with, not just with objects, but I would think also paintings and even works on paper. If the paint layer is porous, some of the consolidant solution could inevitably penetrate into its structure.
I once worked on a museum piece (while on staff at the museum) that was on the verge of self-destructing, and the only alternative we could come up with to save it was vacuum impregnation with HXTAL! The object in question was an iron artifact that was corroded through and through, with large scales that were actively delaminating. Can’t imagine anyone believed even for a moment that it would be a reversible treatment.
Although I was aware that MSA colors and varnishes will become less reversible over time due to the cross-linking of the isobutyl methacrylate polymer (essentially Paraloid B-67), I expected a time span of years rather than months. It’s surprising that this may also be the case with B-72. Best of luck with your project.
Irena
Outstanding. I agree.
I am very interested in the combination of klucel G and sc6000 mixture as was wondering where you got the idea–is there any publication on using this mixture? Also, did you apply it alone or apply a first coat with klucel G, which would penetrate better and then a second coat of the mixture?
I am a graduate student at the UCLA/Getty conservation program and I am doing an analysis of some leather consolidants and decided to include the klucel g with sc 6000 for my project because of your blog.
Thanks Caitlin
Caitlin, thanks for your interest in the SC6000 cocktail and my blog. I did not come up with the idea of mixing Klucel G and SC6000 myself–it was developed at Harvard University Library for the consolidation of powdery leather book bindings (see this post on the Cons DistList http://cool.conservation-us.org/byform//mailing-lists/cdl/2011/1135.html). It is also mentioned in Marion Kite’s book Conservation of Leather and Related Materials on page 232. The combination, dubbed “red-rot cocktail” seems to give better results than either of the consolidants alone. I do pre-treat the areas with 1% and 2% Klucel G in ethanol prior to the Klucel/SC6000 mix. I would love to hear about the results of your analysis if you’re willing to share!
Irena,
Thank you, that information is very helpful. I can certainly let you know of my results. Many thanks,
Caitlin