Salt Bloom?

            While I was sitting in the microclimate-stabilizing room outside the Scrovegni Chapel this weekend in Padova, I watched the video on the Chapel that was playing to pass the time.  It actually turned out to be very interesting, and I learned about a new form of art deterioration that peaked my interest: salt bloom.  I was actually so interested in it that I asked Vijay to remind me about it later for my blog post.  So here I am now, still wondering what salt bloom is.  (Side Note: the Scrovegni Chapel was a funeral chapel, commissioned by Enrico Scrovegni for his father, that was painted by the renowned artist Giotto after its construction began in 1300).

Salt damage in the Scrovengi Chapel Paintings

            It turns out that salt bloom, or efflorescence, occurs when solvent evaporates out of a porous substance, and leaves behind highly concentrated salt deposits that appear as a “bloom” on the painting.  In the Scrovegni Chapel, the salt bloom also caused blistering and distortion in the paintings. These “blooms” happen in everyday life too on our garage floors and sometimes on our walls to, but usually no extreme measures are necessary for removing them due to the regular usage and traffic on and around these items.  However, works of art damaged by efflorescence often require the use of bacteria (solvents can be used, but they are often damaging) to get rid of the unsightly bloom.

Efflorescence from Lipid Accumulation on Leather

            Efflorescence can also appear as the accumulation of fatty acids on the surface of porous materials.  These fatty acids present in the art can arise from a number of sources, such as leather, paints (i.e. oil), and other treatments done to works of art by artists.  There is evidence that some of the lipid crystallization may occur more heavily around certain colors in a painting due to chemical reactions that may arise from the different compositions of the paints.  Researchers are still looking to what kind of deposits form on the paintings and what reactions might make them take place.

            Much work has been done on the Scrovegni Chapel to help restore and maintain its condition.  The microclimate-stabilizing room were sitting in was just one of the mechanisms conservators have devised to help preserve the Scrovegni Chapel, but it is an extremely important one.  By having the microstabilized climate and by allowing only a 25 people at a time to visit inside the chapel, conservators have made definite steps to help avoid more salt bloom from contact with too much of the outside environment, which could cause changes in the paintings’ hydration states.  Hopefully these measures will keep the Chapel looking great for another 700 years.