Batting in backs of framed paintings

Sara Rowe Hignite <sara_hignite [at] aismail__wustl__edu> writes

>Our preparator has been inserting batting into the backs of framed
>paintings--she was told by a conservator that it was necessary to do
>this for paintings that travel. From what I understand the intention
>is to support the canvas so that it doesn't "flap," so to speak,
>when it's being transported.
>
>Have any of you encountered this? Do you advocate this practice? ...

We routinely fill the space between the backing board and the
painting on unlined paintings (and some fragile glue lined
paintings) that are to travel.  By targeting paintings leaving the
museum, as well as paintings passing through the restoration studio,
we assume that eventually all our unlined paintings will have this
added protection.

However, we do not use batting material.  I am assuming that the
batting you refer to is non-woven spun polyester.  Rather we use a
semi-hard Ethafoam that is glued directly to the inside of the
Foam-Cor backing board, which in turn is attached to the painting
stretcher or strainer. It does not actually touch the painting
support but is measured to be at least +/-3 mm away from the
painting.  This is a precaution against the Ethafoam ever pressing
against the painting with the possibility of causing a distortion.

If one is familiar with the way a closed backing board creates a
cushion of air behind a painting reducing any tendency of the canvas
to "flap" when handled, one would also recognize that reducing the
actual air space further reduces the ability for movement.  We use
Ethafoam to fill the space because it gives added protection if the
painting was to be hit from the front. Any impact would quickly be
blocked by the Ethafoam.

In the past we did add a very thin layer of batting material between
the Ethafoam and the painting.  This did give slightly more support
against vibration by creating a physical cushion for the painting to
actually rest against.  I can imagine still using it if the painting
was very, very fragile, but only in the thinnest layer possible.
When we have used polyester, the polyester, being very thin and
light weight, has never slumped downward, even on large sized
paintings.  The polyester fibers seem to cling to the fibers of the
canvas and to the rough surface of the Ethafoam, though I would be
concerned about slumping if a thick layer of polyester was used.

The polyester does however have one greater drawback that also
played into our discontinuing with its use.  That is, it can act
like a large spring if even slightly compressed.  We found that even
the thinnest sheets had to be fully "fluffed" out so that the
thickness never exceeded the actual space available between the
painting and the Ethafoam.  Even when the thickness appeared close
but loose fibers needed to be compressed to fit the space, the
polyester would eventually push against the back of the painting
causing it to distort outward. Since the Ethafoam alone appears to
dramatically increase protection against both movement and impacts
we simply avoid this problem by not using the batting material.

(However, when both polyester sheeting and Ethafoam have been used
with proper measuring of thicknesses no problems have been observed,
even after 10+ years. As such, we have felt secure leaving both in
place).

Laurent Sozzani
Senior paintings Restorer
Rijksmuseum Amsterdam


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                  Conservation DistList Instance 19:4
                  Distributed: Wednesday, July 6, 2005
                        Message Id: cdl-19-4-005
                                  ***