Very frequently it happens that so much of the size and the
superficial layer of fibres must be removed that the mark of the ink
can be distinctly seen on the reverse side of the paper, and the lines
have a distinct border which makes them broader than in the same
writing under normal conditions. If a sharp pen be used there is great
likelihood that a hole will be made in the paper, or a sputter thrown
over the parts adjacent to the erasure.

The latter effect is produced by the entanglement of the point of the
pen among the disturbed fibres of the paper and its sudden release
when sufficient force is used to carry it along in the direction of
the writing.

It is often of importance to know, in case of a blot, whether the
erasure it may partially mark was there before the blot, or whether it
was made with the object of removing the latter.

Inasmuch as an attempt to correct such a disfigurement would in all
probability not be made until the ink had dried, an inspection of the
reverse side of the paper will usually furnish satisfactory evidence
on the point. If the color of the ink be not more distinct on the
under side of the paper than the color of other writing where there
was no erasure, it is probable that the erasure was subsequent to the
blot.

If the reverse be the case, the opposite conclusion may be drawn.
Blots are sometimes used by ignorant persons to conceal the improper
manipulation of the paper, but they are not adapted to aid this kind
of fraud, and least of all to conceal erasures.