Making Wheat Paste (for good mischief)

- designing/copying what you wish to put on the placard using Word/Gimp/Inkscape/Photoshop/whatever
- save it as a PDF
- digging up some cardboard or foamboard to serve as backer
- print the image across multiple sheets which tile to make a bigger version (I found app.docuslice.com to be a reasonable online application that can do that, but you need to use a google login, there are probably other ways to do this, but this was free)
- paste the individual sheets into an array to form the final image
But.. you need glue. Potentially a fair amount of it. Rather than using Elmers or something fancy, you can make wheat paste, a form of glue that has been used by book binders for centuries (and perhaps by graffitti artists for just as long), and consists of two ingredients:
- water (4 parts)
- flour (1 part)
The way I made it was to take 1/4 cup water and 1/4 cup flour and mix them together. Let them sit for a while to fully hydrate the flour. Then heat 3/4 cup of water in a saucepan to a simmer. Then, whisk in the paste/water mixture, and keep stirring to remove lumps until it thickens up. You probably don't want to boil it, but just keep it at a simmer.
And that's it. Frankly, mine still had a fair amount of lumps, but I proceeded to use it anyway. I took an old paint brush and spread some on the card board, and then positioned each tile onto the cardboard backing. I proceeded until they were all glued down, rubbing down with an old rubber brayer I had, but frankly just rubbing it down with your hands will probably be fine. I then set it out in the sun to dry out a bit. After fifteen minutes, I took the brush and applied another coat over the top. Since mine was kind of lumpy, I took a plastic spreader and scraped the worst of the lumps off, and let it dry again.
It worked pretty well. One thing is that the front shrank a bit as it dried so the board curved into a concave shape. I put it under some weight, and it flattened out reasonably well.
Happy 4th of July.