The sto¨ ckigt size test was performed to evaluate the sizing
degree of the silane-treated filter papers according to KS M 7025
[24]. The paper samples of 50 ml silane-treated for 60 min by
immersion method were used for sto¨ ckigt size test, ATR-IR, wet
tensile strength, and Print-surface roughness measurement. The
silane-treated filter papers were floated on a 2% solution of
ammonium thiocyanate and a 1% ferric chloride was dropped on
the upper surface of the filter papers. The sizing degree is the time
of when the reddish brown of ferric thiocyanate appears on the
surface of the filter papers.