Retouching is among the most sensitive within ethics in conservation since it means to establish the aspect a restored object is expected to have.
My opinion is that the looks of an historical object is often as important as its physical-chemical condition, and not intervening provides poor results that might mislead its readability more than a proper intervention. The more we intend to make it as neutral as possible, the least arbitrary, we need to admit that retocuhing requires good taste.
What is a neutral colour?
Is it a pH=7 colour? A transparent colour? Greenish... brown? An oil colour... or maybe acrylic?
Conservators mean by it: "I will paint the missing area with a single colour which you won't see much". It can be green, purple, pencil coloured or either with acrylic paints... Controversial is on the cards and whatever we do, even when not doing anything at all, conservators know that our decision will not suit everyone's taste.
The bike riders from Sants reached my studio squeaking, rather than cycling!
Tears, foxing, discolouration, brittleness, acidity... All these damages have been carefully restored in order to let the splendorous riders finish line at the Municipal Archive of Barcelona. They are almost centenarian... and yet they ride wild along the repository! I'll explain which beauty and health treatments these illustrated posters have passed through