Conservation has evolved a lot from its beginnings regarding criteria. From the restoration intending to give the object an aspect which might have never had, developed by Viollet-Le-Duc (18th century), to many nowadays tendences on conservation that aim to preserve every single modification on the object with the idea that they are all as historically meaningful as the original object. There has been, and there is a wide sort of points of view.
Every theory is valid and can be justified in a particular context. Viollet-le-Duc put more effort on the recovery of the idea behind the object, rather than to the particular object itself, and that involved in some cases portraying himself as Saint Thomas or as a king in two lost sculptures of Notre-Dâme.
Criteria is for sure the most controversial issue behind a conservation treatment, and retouching, as a stage that focuses on the recovery of the visual aspect, is whithin this set of theoretical statements the most sensitive.
All conservators need to deal with it and paper conservators have the drawback that reversibility cannot be achieved as easily as in other disciplines, if ever full reversibility has been a realistic goal .
Book and paper conservation is expected to deal mostly with library and archival material, in which inpainting and retouching has been considered as a secondary aspect in the whole conservation project, whereas in painting conservation, for instance, the way to achieve a particular final aspect is openly discussed.
I sometimes feel that in paper conservation there is some sort of taboo in these topics.
My opinion is that the looks of an object is often as important as the physical-chemical condition of the matter that supports it, and not intervening provides poor results that might mislead its readibilty even more than the lack of intervention.
I am giving for granted that this loss compensation has to be done as a result of a thorough study of the object, its function, meaning, context on the collection, and only after all previous treatments have been explored and exhausted (cleaning, consolidation, application of barrier layers, etc.). Maybe this taboo feeling is due to the thought that conservation has to be the less invasive possible (minimal intervention), leading in the worst acceptation to passivity, to the idea that nothing is reversible enough, distinguishable enough, invisible enough, neutral enough… uh! that it is simply better not to do anything at all. This might risk to lose skills  on inpainting and also to polarize conservation principles (private and public practice).
In my opinion precisely because it is a very tricky issue it should be done the better possible (the most reversible, even if not 100%, the most neutral, the least invasive, etc.), by skilled and trained professionals. This should unify the current standards instead of polarizing them. Speaking out loud about the issues that we come accross while retouching, inpainting and intervenening on the loss compensation in general, can only lead to an improvement of approaches, techniques and results.
Probably we all agree that loss compensation is a process that needs to be considered case by case. Even if using computerized resources to achive the least “faked” result, the most neutral intervention, there is always a necessary sense of taste behind it. And this taste can only be achieved with experience, practice and a wide background of documented examples.
[And, by the way, there are still a few available places in the course Inpainting & Loss Compensation on Paper Compensation, you can still subscribe here].
Here you have three examples of loss compensation on paper. Some of them cover losses, or stains; some of them are done on the same original artwork, while other are done on the infill. Some intend to be the least visible possible, some intend to be visible at a certain degree, some “invent” the loss, some do not involve such critical guesses. Some are fully reversible, some not that much.As a conservator I always have the feeling that results could have been better, but still I think that retouching has improved the final result without misleading meaning and readablility of the object, and of course, being the most reversible and least aggressive regarding its chemical and physical aspects.
This page belongs to an artbook about Dalí’s work, with a felt-tip pen dedicatory on the first page by the Salvador Dalí (first image). This page had a glue stain next to the signature. I removed the glue but then the different oxidation degree due to the glue provoked that the stained paper was less yellowed (2nd image). The las image is after applying a watercolour layer on the stain to make it less visible.
Oversized gouache drawing, which had a very brittle painting layer. After cleaning and consolidating, the losses where in-painted on the original with gouache, in a low level criteria (using a paler tone) since there was not any big loss requiring an interpretation of the drawing lines.
Oversized gouache drawing on sketch paper with similar features from the previous example (very brittle painting layer) and similar treatment (wet cleaning and consolidating) but in this case the losses where in-painted on the infills, with watercolours and gouache. In this ocasion the in-painting criteria was mimetic on the smalles losses, intending to re-create the drawing on the loss in the smalles areas, and a neutral colour fieldon the biggest ones. The conservator doesn’t mean to equal the artist’s hand, but in this particular drawing, with somehow caotic lines all over the surface, the losses sort of get integrated in it appearing at first glance as one of those lines and strokes. My opinion is that in the smallest gaps, the in-painted loss creates less confusion that a not intervened loss. On the bigger ones, which are luckily on the left bottom corner, I thought comprehensible enough to leave a neutral colour field, hoping the observer will understand it as a loss, and not part of the object , in a way that is not too highligting nor disturbing either.
The city Council of Sant Cugat, for providing me the opportunity to work in such a nice object (Example #2) and also the private owners of the 1st and 3rd examples. All these object requiered tricky decision making and visual result was quite important, making all these conservation treatments challenging and enriching to me. Thanks a lot!
 Reversibility – Does it Exist? British Museum Occasional Papers, #135. Andrew Oddy, Sara Carroll. British Museum Press (December 31, 1999). ISBN-13: 978-0861591350, ISBN-10: 0861591356.
 Jonathan Ashley-Smith (2016) Losing the edge: the risk of a decline in practical conservation skills, Journal of the Institute of Conservation, 39:2, 119-132, DOI: 10.1080/19455224.2016.1210015 Ashley-Smith has also commented himself this paper in an IIC post (click here).