Pour the mixture into your container, let it cool, and then paste it up! You can toss the extra in the fridge for later, but after a couple days the wheatpaste will go bad and you’ll have to make a new batch.
Although I've largely given up wheatpasting my posters in favor of less illegal and less marking means of getting up, I started postering with wheatpaste, and had to pick a method of transporting it around. I looked online to see what other people were doing, and I wasn't fully satisfied with their methods. The two most popular seem to be traveling with an open bucket of paste and a brush (for larger works) or traveling with a water bottle, one you can use to squirt paste on your surface of choice, and a brush to smooth it around. The trouble with these methods is that you're left with the problem of a brush covered in wheatpaste, and that'll lead to sticky and white wheatpaste getting everywhere. One of the things you'll learn when you start wheatpasting is that it doesn't dry clear. It dries opaque white. A sloppy night of wheatpasting and you'll look like the star of a bukkake video. You may want to wear white, by the way.... so here are two containers I came up with, both of which solve this little problem. They are both cheap and easy to make, but they do require the use of knifes and hot glue guns, so be sure to ask an adult for help, ok? Enjoy!
Number one: The "Rubber Cement" container
Get yourself a wallpaper brush or some kind of brush at the hardware store. Then go to the dollar store or look around the house for some sort of container that is deep and wide enough to accommodate the brush and has a watertight lid. Something like a little bucket with a lid will do nicely. Here's what I used.
(You may want to buy two of your containers, in case you crack the bottom of one, or just to have an extra lid that you can use instead of the lid with the brush attached when you want to store your leftover wheatpaste. This way you can store it without the brush inside.)
Then cut or drill a hole in the lid that is just slightly too small to fit the handle of the brush. This is so when you put the handle inside, there will be a pressure fit. Seal up around the handle on the inside and outside with a little hot glue or whatever works.
The nice thing about this is that the lid will also act as a sort of spill and splash guard, so it's even less likely you'll get it on your hands.
and there you have it!
Simple, no? Just fill it up with paste and your ready to roll. The leftovers will store fairly well for at least a couple of weeks or so inside of a refrigerator. You can leave the brush inside if it is submerged in wheatpaste, if it is not, however, you'll want to take it out, clean it, and cover your container with your spare lid or some plastic wrap. If not, this'll happen.
not fun to clean....
Number Two: The "Wheatpaste Wallet" container
Again, head to the dollar store and get yourself a pair of rollers and trays. Then turn them so their lying "head to foot", and tape/glue them together! The edges can be tricky to seal, so be careful.
It'll look something like this. The green is from some latex paint I poured around inside to help seal off the leaks. I don't really recommend doing that, however, because it'll flake off into the paste. I don't know if that'll bother you or not.
Then cut a whole in the top, large enough for you to fit the roller head through (sideways) without scraping the paste off the sides of it. The way you use this is pretty self explanatory, I think...
I will recommend that you get a messenger bag, (The type of bag that slung from one strap across your body and hangs at your hip) both the wallet and the "rubber cement" container will fit in nicely, won't be knocked upside down, and can be accessed and covered up quickly and discreetly. And remember, when a cop asks you "Can you show me what you have in the bag?" it's because he can't search your bag without a warrant, and needs you to volunteer to show him yourself, ..so... don't.