John,
Partly, that depends on which gesso was being used.  White lead ground in
linseed oil is one gesso, calcium sulfate (plaster of paris) is another.
Both can be very difficult to remove, and are chemically reactive.  Both
can be very durable.  It all depends....
 
Jack
Thompson Conservation Lab
Portland, OR
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On Wed, 7 Sep 1994, John M. Harris wrote:
 
> I have followed the discussion about WhiteOut with interest, and finally
> decided to "jump in."
>
> Many years ago ... too many, I fear ... I was taught to use gesso, write
> the number with India ink, and cover with a coating of clear nail polish.
> I have been surprised that no one has mentioned gesso up to this point.
> Are there similar problems with this product and procedure?
> Jmh
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