1. Presoak your paper at least 15 minutes in tap water that is as hot as
you can stand to the touch. Make sure that the water remains hot
throughout the time it is being used. Use constant agitation. If you are
doing several sheets at one time, move the bottom sheet to the top
continuing this process throughout the required time. Eliminate any air
bubbles on the surface of the paper and make sure all areas of your paper
are evenly wet. Hang to dry by two corners. This is basically a stage of
preshrinking your paper before the application of the size.
2. When dry, mark the back of your paper with a small x or your initials
in a lower corner. Dissolve 30 grams of knox unflavored gelatin in 1000 ml
of distilled water. The water should not be hotter than room temperature.
Stir gently for 15 minutes as the gelatin absorbs the water. Slowly heat
this solution to a temperature of at least 125 degrees F. Hotter is better
but do not exceed a temperature that you can stand to the touch. While
this is being heated mix 2.5 grams of chromium potassium sulfate (chrome
alum) in 60 ml of distilled water. Heat this solution and very carefully
and slowly pour into the gelatin while stirring constantly. If the chrome
alum in not close to the temperature of the gelatin or you pour it in too
fast without stirring, it will lump the gelatin and you will have to begin
all over again. Pour the gelatin/chrome alum mixture into a clean tray that
will easily accommodate the size of your paper. It is helpful to have that
tray inside a larger tray into which you can pour extremely hot water to
keep your gelatin mixture from becoming too cold during the process of
sizing. Soak your paper in the size (gelatin/chrome alum) again moving the
sheet on the bottom to the top etc. for at least ten minutes. Make sure
that no air bubbles are on the surface of the paper and the gelatin has
been evenly absorbed into the paper. Take one sheet from the gelatin and
place against an inclined plane of glass that is very clean and free of all
dust. Place the sheet so that the back, the side that you have marked with
an x is face up. Use a glass or plexiglass rod, that is at least as long as
the shortest dimension of your paper, applying even pressure forcing the
gelatin into the fibers of the paper. The excess gelatin will slowly run
down the glass. Turn the paper over and repeat. Hang to dry by two
corners.
3. When dry repeat step two. It is best not to try to save the gelatin
as it becomes contaminated with dirt. This may be done yet one more time
to insure a very even and well sized surface. Step two must be done twice
and three times is optional. Sized paper will keep indefinately.