In the case of manila paper,
a dark red color was obtained which suggests
phenolphthalein should not be used when suspected
stains adhere to this type of background. Tincture of
iodine produced a weaker positive before the
addition of peroxide. In both instances with the use
of the three stage test, these results were clearly not
false positives. It becomes obvious however, that a
one stage test is not desirable because of reduced
specificity.
Conclusions