Letter: A genius for combining unpleasant colours

Sir: Peter Fellgett in his letter (15 April) on the restoring of Old Master paintings claims that scientific methods can discriminate between a glaze and a final varnish with certainty. I use a traditional painting technique with glazes, which are essentially coloured modifying layers of varnish, sometimes as thin as a breath, and I cannot believe it would be possible to decide where these end and the final varnish begins, especially if the latter was discoloured with age or dirt. Titian is famously quoted as using many glazes, but the blue sky in Bacchus and Ariadne looks very like a base colour awaiting the translucent aerial effect of glazing.

It is interesting to note that a letter written to the Times, on 14 July 1946, by Pietro Annigoni, an artist of undeniable craftsmanship, includes the following extracts:

At the National Gallery I noticed once more the ever increasing number of masterpieces which have been ruined by excessive cleaning . . . the most essential part of the completion of a picture by the Old Masters comprised of innumerable glazes, often mixed with final layers of varnish . . . One should clean off dirt or recent coats of varnish, but to proceed further is to commit a crime of enormous presumption.

I must disagree however with Bryan Appleyard's approval of the cleaning of Michelangelo's fresco in the Sistine Chapel ('Old Masters vanish before our eyes', 8 April). I have had experience of this technique, both as Annigoni's assistant and on my own account, and I am convinced that Michelangelo would have used a simple egg tempera for retouching when the plaster was dry: thus a cleaning technique which removes everything but the original lime plaster surface can only be suspect.

To claim scientific infallibility and certainty in this area is rather arrogant.

Yours faithfully,

ROBERT WRAITH

Holton, Oxfordshire

16 April