How to Stretch Watercolor Paper
Watercolor Painting Lesson

First, why would you want to stretch paper?

When you don't stretch the paper it buckles and leaves puddles of water and pigment all over - looks dreadful. So you stretch it, it's taut and smooth and the pigment stays where you paint it, doesn't travel off on its own. Use at least 140# paper, 90# paper will puddle & get damaged no matter what you do.

You need:

paper (I use Arches 140# hot press).

stapler

water (tub, shower, sink, or sprayer)

gatorboard (verythick foam core) (there are other choices - this is what I like)

Soak the paper until it's sopping and limp; be careful not to crease it while wet (or dry) as the sizing will be damaged and show up on your finished work as a line with too little or too much pigment.
Place it smoothly on the gatorboard and staple it around the edges every 4 inches (approx).
L et it dry until it's dry (it will shrink taut and smooth).
If it buckles, take it apart and do the whole process again - your paper is the foundation of your entire painting. If it's buckling, the entire painting falls apart.