As response to the questions brought up in our "Intro to Street Art", "Mixing the Media" and "Adult Mixed Media" classes - we've put together this two-part tutorial on how to make and apply wheat paste when doing paper posters and collage:
Part 1: Wheat Paste recipe and cooking
1 part flour to 4 parts water (This demonstration uses 1cup of white flour with 4 cups of water)
In a small pot, whisk together flour and water with wire wisk.
Bring mixture to a slow boil (med-high heat for 5-8 minutes) until mixture has a gluey gravy-like consistency.
Remove from heat - you can add 1/4 cup of sugar or white glue to make the mixture even more tenacious (sticky)
Wheat Paste can be refrigerated to stay "fresh" longer. Consistency may change (it will get thinner), however, the paste still works. Be mindful that wheat paste will spoil in time especially if kept at or above room temperature.
Part 2: Applying Wheat Paste with paper posters
Use a wide brush to apply the paste to the intended surface or substrate. Apply a thin layer the approximate area of the poster.
Apply a thin layer of wheat paste to the back of the paper poster.
Press center of the poster against the wall and begin brushing the poster from the center out to the edges with your brush.
When the paste is still wet (and the paper is still malleable) you can peel and reposition if the paper has trapped too much air)
Finally brush a thin layer over the entire poster and especially the edges.