grains—and toward the center of the panel. The back of the frame should
always project beyond the picture to prevent the panel from pressing
directly against the wall. Also, a backboard of some sort helps to act as
an environmental buffer and to prevent accidental damage.
When the panels are housed in an uncontrolled or fluctuating
environment, it may be necessary to incorporate the panel and/or panel
and frame—whether in a tray or not—into a vitrine (to assist in reducing
the fluctuation of temperature and RH between the panel and surround-
ing air) or into a climate-controlled exhibition case.This small (45 3 34 cm) panel is a fragment of the Annunciationby Cosmè
Tura (1431–95), probably painted around 1480. The picture is on a poplar
panel painted up to the edges and clearly cut all around. It was acquired by
the National Gallery in1874 and recorded to be in good condition. In 1915
the old parquet (cradle) was removed, and the breaks were reset (through
the head in a vertical line and elsewhere). The panel was then veneered,
and a new parquet was applied. In 1991 the picture was proposed for clean-
ing and restoration, procedures that were carried out by Jill Dunkerton. The
structural work was done by the author and David Thomas.^2Case Study: Treatment of a
Painting by Cosmè Tura410 Reeve
- Canva s ir on ed onto th e ba ck and over the sid es
of the balsa -wo od bu ildu p with wa x and res in - Sec ond la ye r of ba lsa woo d la id
at rig ht ang le s to th e firs t lay er and
sc or ed on the unde rs ide as a ke y - Firs t la yer of ba ls a-wo od
plank s laid wi th the grain
ru nn ing in the same directi on
as the orig inal pa nel and
sc ored on bo th si des as a key - Wax , damma r,
resi n, and woo d flo ur
pour ed ove r th e first
laye r of bal sa wo od - Wax , damma r, resi n,
and wo od flour pou red
over the hes si an inte rle af
The bals a-wo od pla nks
are ag it at ed in to po sitio n
to di sp erse the air an d
le ve l out the wa x mixture - Orig in al pan el
- Op en-we ave hessian
(b url ap) iro ned into wax
and resin on th e back
of the panel - Wax and damma r resin
ir oned into the pa nel
Figure 6
Diagram of the old method of balsa-
woodbuildup.