NPG BTS: Conservation of a Pencil Drawing – National Portrait Gallery

NPG BTS: Conservation of a Pencil Drawing – National Portrait Gallery

But we actually haven’t exhibited it very
much. We might have put it up in the recent acquisitions
show very briefly but the condition was so sort of unsightly that we really haven’t used
this. We really haven’t exhibited it. This delicate pencil drawing is from the collection
of the Smithsonian National Portrait Gallery. It is of Daniel Webster by Albert Gallatin
Hoit and is dated circa 1854. It is somewhat compromised by this reddish-brown
spotty staining known as foxing. Foxing is thought to be a fungus or iron deposits
in the paper that discolor in high humidity. After consultation with the curator of prints
and drawings at the National Portrait Gallery, Wendy Wick Reaves, it was decided to reduce
the staining by washing the drawing on a vacuum suction table. The first step in the washing process is to
humidify the paper, relaxing the paper fibers so that the drawing can be placed on the surface
of the suction table. The drawing is supported over a tray water
and covered with a transparent acrylic sheet. Once the drawing is thoroughly humidified,
it is time to move the drawing to the suction table. The suction table was chosen due to the delicate
nature of the graphite pencil. The drawing is carefully placed inside the
opening of a polyester sheeting and is carefully flattened out as the suction is gradually
increased. The suction table holds the drawing in place
as water solutions are drawn through it to reduce the staining. The paper is further humidified by spraying
a filtered water. A narrow air space is left around the perimeter
of the drawing so that the ambient dust particles can collect. Excess droplets are blotted from the surface
of the polyester. The second part of the washing process continues
by spraying the paper with a specially formulated water solution. The suction allows the water solution to be
pulled through the paper, which solubilizes some of the degradation products. The blotter is changed when it becomes saturated. The brown discoloration washed from the paper
is visible here on the used blotter. The process is repeated until there is no
more discoloration being pulled through the paper. When the washing is finished, the drawing
is then removed from the suction table and placed on a dry blotter and left to air dry. Once again, the drawing is humidified in the
chamber and then placed between blotters and felts along with a gentle weight and left
to dry. The final result is a delicate pencil drawing
that is more stable condition and improved in appearance. Now that it looks so wonderful, Rosemary,
it would be fun to put it up again. It’s really much improved. It’s actually very delicate the way he’s
modeled that face. Just a very soft little hatching around the
cheeks and around the dome of the head. It’s really very sensitively done.

2 thoughts on “NPG BTS: Conservation of a Pencil Drawing – National Portrait Gallery

  1. Well I know these guys are conservators, but I hate to tell them, the foxing will return because it is a part of the molecular structure of the paper. In fact you can analyse the foxing and determine where the paper was made due to the mills water source, it is also a component of paper made with rags rather than pulp. If they don't want the foxing to return, the product should be sealed in an air tight frame filled with inert gas – but they should know this but like to present a superior attitude.

    As to the post below made 9 months ago, they will never reveal their formulas. If they did they wouldn't be in the "conservation" business very long. Plus this is extremely expensive work. And they'll never tell you how many pieces of art they screw up and can't be recovered.

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