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the controversy is called The Ravished Image: or How to Ruin Masterpieces by Restoration (Walden 1985). Recent well-known examples are Leonardo da Vinci's Last Supper (Barcilan, 2001) and the Sistine Chapel (Pietrangeli, 1994). The conservators removed all the previous repairs to reveal the artist's work with the result that a lot less pigment is on display now.
There are several things conservators can do to restore colour, two being:
* Conservators can leave the repair unpainted; this can often stand out too strongly, detracting from the artefact. Conservators can paint the infill a constant bland colour, usually similar but slightly lighter than the artefact's colour, and
* We can try to recreate the patterns, shadings and textures of the original, making the gap fill almost invisible. The profession does not like to restore an artefact, i.e. making it brand new
The latter is very time-consuming and it is often the case that the time spent making an artefact look good is better spent saving another artefact.
Many artefacts come to the laboratory suffering from an irreversible chemical reaction that we have to stabilise. Examples of this sort of treatment include the following.
Archaeological iron usually contains a large amount of chloride salts. If these are not removed by prolonged soaking in chemicals, the object falls apart. Very deleterious rust forms (chemically: beta iron oxy-hydroxide) as an artefact changes its environment from burial to museum. Untreated iron only has a half life of eight to eleven years (Keene and Orton 1985).
If archaeological bronzes or as we prefer to say copper alloy (as bronze is a specific alloy of copper and tin) contain too many chloride salts, a corrosion product forms known as bronze disease that can turn the artefact, ultimately, to a light green powder. This corrosion product can be stabilised by removing as much as possible of the offending corrosion product and stabilising the damaged areas with silver oxide.
389
the controversy is called The Ravished Image: or How to Ruin Masterpieces by Restoration (Walden 1985). Recent well-known examples are Leonardo da Vinci's Last Supper (Barcilan, 2001) and the Sistine Chapel (Pietrangeli, 1994). The conservators removed all the previous repairs to reveal the artist's work with the result that a lot less pigment is on display now.
There are several things conservators can do to restore colour, two being:
* Conservators can leave the repair unpainted; this can often stand out too strongly, detracting from the artefact. Conservators can paint the infill a constant bland colour, usually similar but slightly lighter than the artefact's colour, and
* We can try to recreate the patterns, shadings and textures of the original, making the gap fill almost invisible. The profession does not like to restore an artefact, i.e. making it brand new
The latter is very time-consuming and it is often the case that the time spent making an artefact look good is better spent saving another artefact.
Many artefacts come to the laboratory suffering from an irreversible chemical reaction that we have to stabilise. Examples of this sort of treatment include the following.
Archaeological iron usually contains a large amount of chloride salts. If these are not removed by prolonged soaking in chemicals, the object falls apart. Very deleterious rust forms (chemically: beta iron oxy-hydroxide) as an artefact changes its environment from burial to museum. Untreated iron only has a half life of eight to eleven years (Keene and Orton 1985).
If archaeological bronzes or as we prefer to say copper alloy (as bronze is a specific alloy of copper and tin) contain too many chloride salts, a corrosion product forms known as bronze disease that can turn the artefact, ultimately, to a light green powder. This corrosion product can be stabilised by removing as much as possible of the offending corrosion product and stabilising the damaged areas with silver oxide.
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