it's time to look at how to go about doing it.
The first step was to stablize the environment. It's been made clear already that lheat and moisture can be harmful to artwork, but this is even more crucial when the work is in the vulnerable state of restoration. It was determined that the perfect climate would be 55% humidity between 20 and 25 degrees C. For this task,92 tiny air-conditioners were manufatured, the smallest every made and stratiegically placed to both stablize the environment and not detract from the artwork.
The next step of restoring any work of art is to assess exactly how bad the damage is and what needs to be done. It is also crucial to discover the compounds used in the artwork so that the restorers can avoid unexpected reactions.These two go hand in hand because over time, reactions can occur and change the structure of molecules in the artwork. Technology is constantly coming up with new ways for us to do this so it's hard to choose any one way.
Though the methods used in the chapel restoration have changed over the years(the wall frescoes or "lesser" frescoes were begun in 1960,the cieling, finished in 1994) the following are some of today's more popular techniques.
X-Ray Fluorescence Spectrometry
(XRFS)
This techinique and several others which also involve X-rays are used for restoration and elemental analysis. An X-ray is directed at the sample which then reacts with the atoms used, eciting the electrons. From this, a spectrum is produced specific to a particular element. A charcteristic X-ray is produced when the sample absorbs the X-ray's energy and the photon(no, not futon, photon:quantum of radiant energy)is changed when it bounces away. Otherwise(when the photon remains the same, as a couch) the collision is called elastic.
So, this is all useless right? WRONG!
the number of characteristic x-rays for any one element is proportional to the concentration of that element.This technique shows restorers both what elements they're dealing with and how much is present in a given area.
This technique is used by directing a very brief (a nonasecond) laser beam at the sample which then dissociates(separates ions) and partially ionizes. This forms a plasma, which is a state composed of electrons and positive ions that have been knocked apart at high temperatures. As the plasma cools, radiation characteristic to the elements are produced and the rest is the same as XRFS.
This method should be used sparingly because it does consume minute layers of the sample as it works. however, this same drawback also allows it to analyze the elements in a cross section of the sample.
Other similar techiniques have film that the radiation bounces onto and colors. Many are attached to computers to project the images and dot diagrams of element content.
Cleaing the Capel ceiling was much like cleaning any other work of art. The dirt and ancient tree resin which was discussed previously could be carefully cleaned with a gentil polar solvent that will easily dissolse the smaller molecules of the tree resin and will not dissolve the paint becuase all of the paints are oil-based.Of course, it goes without saying that one must first know the compounds in the paints so that no chemicalwill react and furthur damage the painting.
So, painstakingly restorers rub polar solvents on the surface.
Well, it's actally a very delicate project and is done slowly under microscopes.
Okay, The art/chemistry groupies use polar solvents gently cleaning the frescoes under microscopes. Of course, we can't forget, the Sistine Chapel has a ceiling too.
Upsidedown microscopes.
Suddenly it's not so easy, and to top it all off, these are frescoes.
Frescoes are made with a unique process in order to solidify the paint. When an artist is painting a frescoe, they first apply a paste of calcium hydroxide to the surface they are painting. over the next few days, the calcium hydroxide reacts with the carbon dioxide in the air to become calcium carbonate. This is the same stubstace that's found in both marble and limestone. This process traps the paint within the calcium carbonate crystals and essentially makes the painting not a painting, but a splendifurously beautiful wall of stone.
Inside these stones, other crystals begin to form, bad scary crystals. These crystals are potassium nitrate crystals. This is a very serious problem for a work of art. Pressure that builds over time presses the crystals against pores in the stone cracking and weakening the stone like ice under pavement.
Also as time passes calcium cabonate in frescoes turns to calcium sulfate. The presence of nitrates and other salts can speed up this process. Calcium sulfate crystals are larger than clacium sulfate crystals and degrade easier, forming a whitepowder over the painting which also steals some of the pigment from the frescoes. In 1970, a method was developed to help these poor powdered frescoes without completely removing them from the wall....or ceiling.
The first step of this process is to apply a solution of ammonium carbonate to the surface.This reunites the long lost calcium carbonate and produces ammonium hydroxide which is water soluble and can be easily washed away.
CaSO4 + (NH4)2CO3---------->CaCO3 + (NH4)2SO4
Next, a solution of barium hydroxide is applied which produces barium sulfate and carbonate crystals which will partially fill the cracks made by the nitrate crystals.
CaOH2+CO2------------->CaCO3+H2
So apart from all this, there's still the manner of those crazy clothes on the Sistine figures. You see, when preparing for the restoration, Scientists noticed that there was an added layer of paint that covered Michelangelo's nudists.As for this, there was little chemistry involved. It would be too dangerous to remove the paint with chemicals. Instead, restorers worked carefully wtih tiny needles and high tech tools such as pig hair to pick away the constricting robes.But at last, it was done and so, Michelangelo's free spirted clothing embargo was again known to the world.
The very last step (Ha! you thought it was done with the nudists!) was to help ensure this restoration will keep. The restorers applied a new resin, this time non-organic and formulated to be removable and longer lasting.(More about this with the next page.)
