Tony Clayton wrote:
I recently purchased a very scarce mint Italian
stamp that completes a difficult mint set - at long last!
(the Victor Emmanuel II set of 1863).

The stamp has clearly been regummed, and was purchased
below the Sassone 'without gum' price.

With a glass the gum is clearly visible on the front of a few of
the perforation teeth, and there is some on the front
of the stamp, but none of this is visible to the naked
eye when in the Hawid mount on my album page.

The question is, should I soak off the 'added' gum,
or leave it there?

Original gum is very rare on the oldest Canadian stamps, and the
Unitrade catalogue prices these stamps in an ungummed state, with a 100%
surplus added to the value of these stamps if they have original gum.
Regummed stamps are worth no more than stamps without gum, so I always
soak any regummed issues. There's always a fear that this mystery gum
might affect the stamps, similar to those German issues that contained
an acid in the gum.

Ryan