An unexpected former use of the painting
Detail of x-ray, showing keyholes
What else does the back of the panel reveal?
The most interesting features on the back of the panel are the three plugged key holes at the left centre and the hinge marks at the top and bottom. From these we can be certain that this painting was a door at some time. The very worn, soiled surface at the centre left edge suggests that the door was used frequently over a long period of time. The three locks suggest that it may have been the door to a room containing something of value.
How did the painting come to be used as a door?
The St Michael panel was probably originally one part of a large altarpiece or retablo. It is likely that when this was dismantled our panel was made into a door, possibly for the simple reason that it may have fitted the doorway with only slight alterations needed. It is tempting to think that this striking image of St Michael (who guarded the gate of heaven) may have been thought appropriate for the locked door to a room of valuables, for example a church or monastery treasury or sacristy.
Detail of the mark made by a hinge on the back of the panel
How was it altered to become a door?
We think the vertical sides of the panel were cut down to fit the doorway. This would explain why St Michael’s sword and wings are truncated. The shaping of the right edge at top and bottom would have been made to accommodate the hinges. The keyholes would have been cut into the thickness of the wood. The back of the panel has been painted several times. The last two coats of blue then white paint were applied when the hinges and keyplate were in place and so definitely during the period when the panel was in use as a door.
Are there any other examples of paintings used as doors?
The Westminster Retable, which was painted for Westminster Abbey in the 1250s, was reused as the lid of a large cupboard for centuries after it was replaced with a new and more fashionable altarpiece.
There is also an example of a hidden keyhole in Ercole di’Roberti’s ‘Pietà’ from the Walker Art Gallery's collections.