To Box Or Not To Box Your Paint?
Chances are you won’t be using just one gallon of paint to paint a room unless is a small bathroom. Any purchase of a specific color paint less than five gallons will usually be given to you in individual one-gallon paint cans.
It a good general practice to box, or mix all of these individual cans together prior to painting. A five-gallon bucket with a lid works beautifully for this task. Just empty the content of each can into the bucket. Use a large paint stick or a paint mixer that can be attached to your drill, and mix the paint for a minute or so.
The reasoning for this is sometimes there can be variations in the color, and it accounts for human error. Especially if you may have bought some paint at one store, and then the rest at another. Even the slightest difference in calibration of the store equipment can show up on your walls, and you really do not want that. Also, be sure your cut can is filled after boxing the paint as well. Any variation with show a difference from where you cut in with your brush, and where you rolled the walls. This is called haloing.