Watercolor Paper for Cyanotype

[Joe Tait <jtait@texas.net>]

I was making a cyanotype test print of a hand-painted negative (on clear
acrylic) and decided to try a watercolor paper, whereas before I had been
using printmaking paper (forgive my ignorance, I believe the watercolor
paper is Arches 90lbs.). I liked the far smoother surface of the watercolor
paper, but it didn't hold up well in the washing (which at 18" x 18" needs a
fair amount of washing). There were a few places where the paper started
separating. Also, the paper was buckling somewhat after it was coated.

Would sizing solve this, or should I use a different paper altogether? Maybe
someone could suggest an ideal paper that; 1) is really smooth 2) has the
least buckling as the acrylic "negative" is also the glass holding the paper
flat during exposure.

Thanks.

-Joe