This tutorial will demonstrate a couple ways to flatten paper that has buckled (gotten bumpy due to moisture, specifically watercolor paper) without fancy equipment like a heat press.

All you need are a few household materials:
clean, thin towels
newsprint (optional)
spray bottle or damp sponge
clean, hard surface such as a table or drawing board
heavy objects like books, weights, etc...
iron
ironing board

For more info, check out this site:
https://www.strathmoreartist.com/blog...