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The Principle of Reversibility

Alright guys, I’m back with another video on art conservation. It's been a while since I’ve done one of these, this is going to be exciting.

Today we’re talking about the principle of reversibility, and why this concept is so important when working in conservation and treating objects.

The Principle of Reversibility is one of the main tenets in modern “church of conservation” let’s say. It’s even written into the American Institute of Conservation Code of Ethics:

The conservator is guided by and endeavors to apply the ‘principle of reversibility’ in their treatments.

They should avoid the use of materials which may become so intractable that their future removal could endanger

the physical safety of the object. They also should avoid the use of techniques the results of which cannot be

undone if that should become desirable.

Essentially, we want to do our best to only use materials that we can remove afterwards in case they’re ageing badly, if the treatment doesn't come out as expected, or if the material becomes unstable. Not to mention that more appropriate, safer materials may be developed or become available in the future (thanks, science!). We want to make sure that the possibility to replace our old material for something better is always there. Conservators and researchers might also find something out about the object as time goes on, which would call for it to be retreated. For example, maybe we interpreted the object as one thing, and then 50 years later we realise it was actually something else! We’d then need to remove old treatments and treat it accordingly.

Conservation is all about minimal interference. We don’t want to add our own narrative or interpretation into the object, we just want to protect its integrity. Of course, this is philosophically almost impossible because we always make choices based on our own inherent bias and leave our mark, and we’re not always able to use completely reversible materials…but at least the notion is still there, and it’s the thought that counts!

Reversibility is what sets conservators apart from restorers or repairers. We want to make sure our interventions can be undone. And that right there is the whole intent that we set when planning the treatment of an object. Conservators have an obligation to ensure that the condition of an object does not change for a long while after conservation treatment is completed. But also, we have to make sure that if the condition does change in any way, we can remove old treatments and protect it again with new materials.

Attic Black-Figure Krater, known as the Francois vase.

You can see the fills and repairs, but it doesn't interfere too much with the readability of the object. ​

Let’s not forget about aesthetics when talking about reversibility. Tastes can change over time on how we present an object, whether it be how objects are displayed in cases, or how objects themselves are seen. For example, in the past, it was very popular to fill all losses in ceramic pots, and retouch them so it looked like one complete vessel. Today, we’re seeing more of a trend to show the losses in these pieces to spread awareness on how objects like these are found in the archaeological context. That, and the old way of reconstructing them is now deemed too much of an intervention. In this case, it’s very important that the old restorations can be removed without posing a risk to the original material, in order to treat it again in today’s ‘fashion’.

Glass is often too thin and fragile for thick adhesives like Paraloid B-72. ​

Therefore, thinner and stronger epoxy resins are needed in order to make sure

they're stable enough.

Of course, some conservation efforts may not be reversible, and there’s no avoiding that. Sometimes, a reversible material for the job at hand just isn’t available yet. For example, we often use special epoxy resins for thinner glass, because reversible glues are too thick, and not strong enough to hold the pieces together, or to make the glued edge fit tightly. As a conservator, the safety and stability of an object is the most important thing. We need to the best we can with what we’ve got. Of course, we run through the list of reversible options first to see if any of those could be a good fit, but if we can’t use any of those, we have to compromise.

There are obviously some things we do quite regularly that aren’t reversible. For example: cleaning. We can’t just replace all the dust and dirt we’ve cleaned off. Cleaning is an essential part of the conservation process, but we do need to ensure that we aren’t taking away any original material, or any sort of residue that could be of historical significance and provide information about the object. For example, if the object came from an archaeological setting, and some things could be determined by the residue found inside, that’s something you’re gonna wanna keep.

There’s another term that floats around when discussion reversibility, and that’s re-treatability. This has become more common than reversible, because the term reversibility can be a bit controversial. Of course once you interfere with an object, you can never fully return it to the original state, so the concept of re-treatability kind of covers your bases. If you’ve consolidated something with a resin that technically is reversible in solvent, it’s unlikely that you’ll ever get it out because it’s been absorbed into the fabric of the object. But that’s a good thing. As long as it’s stable and a good material anyways, because it was most likely consolidated because it was unstable and this sort of treatment was necessary.

So that's the principle of reversibility for you! Hope you found it informative, and remember to keep this in mind whenever you are approaching the treatment of an object.

Have a question? Email me!

Looking to find out more?

American Institute for Conservation Code of Ethics

European Confederation of Conservator-Restorers Organisations Professional Guidelines

Criteria for Treatment: Reversibility by Barbara Applebaum

Journal for the American Institute for Conservation

JAIC 1987, Volume 26, Number 2, Article 1 (pp. 65 to 73)

The Concept of Reversibility in the Structural Restoration of Archaeological Sites by S. D'Agostino & M. Bellomo

Universitci degli Studi di Nupoli Federico 17, Italy

Transactions on the Built Environment vol 66, © 2003 WIT Press,


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