How to Stretch Watercolor Paper. Watercolor paper with a weight of less than 140 lbs. will need to be stretched before use. Stretching prevents the paper from buckling or warping when paint is applied. Here are tips on how to stretch your watercolor paper.
Cut watercolor paper to the desired size.
Cut four strips of paper tape equal in length to the sides of the watercolor paper.
Place all materials close to the sink.
Fill the sink with lukewarm water.
Dip the watercolor paper in the water, wetting the front and the back of the paper completely.
Place the wet paper on a drawing board.
Moisten the shiny side of the paper tape completely with a sponge.
Fasten all four sides of the paper to the board using the paper tape.
Place the board on a flat surface to dry.
Allow the paper to air-dry completely.
Remove the paper from the board after your painting is complete.
Stretch 140 lb. paper if you are planning to apply heavy washes of paint. The wet watercolor paper will buckle when it is first placed on the drawing board. As it dries, it will flatten out. Remove paper from the drawing board using a razor or palette knife.