How do you use a paint roller on a wall? With a little practice you can be competent at this skill in no time at all. Below, I'll outline a few important mistakes to avoid as well as some good practices that will put you on the path to using a paint roller like a pro.
First, what to watch out for.
When your roller first makes contact with the wall, don't start at the top or bottom. Instead start somewhere in the middle (vertically speaking). If you roll a wall from top to bottom or from bottom to top you'll have to spread the paint a long ways to reach the opposite end.
Also, don't start in the middle of the wall (horizontally speaking). Work from left to right, or right to left. This will help you to keep a wet edge while you are painting. If you are always rolling over paint that is still wet then you will always be spreading and evening out the coating. However, if you roll over paint that is already dry then that is an additional coating and it may affect the appearance of your final coat.
Don't press hard on the roller. Light to moderate pressure is all that is needed to push paint out of the roller. A rule of thumb I like to use is let the weight of the roller do most of the work. If you need to push, use light pressure. If your roller is running out then go back to your tray or bucket and load it up again.
I also like this rule because it's a lot less tiring to less gravity do most of the work, especially when you're painting big rooms or you haven't trained your muscles for the repetitive nature of painting.
Two reasons not to push hard on your roller:
1.The harder you push the more your nap compacts which changes the thickness of the nap and affects how it applies paint into the valleys of texture.
2. The harder you push, the more likely you are to push unevenly and create a line of paint at either end of the roll.
Try to find a pattern that you can repeat over and over again to make the task of rolling the wall progress steadily. I like to make 3 vertical passes with each load of the nap in this order:
starting from the end of the last roll in the middle of the wall: middle to top to bottom
crossing back over the last roll half way: bottom to top to bottom
crossing ahead over the first roll half way: bottom to top to bottom
(video demo coming soon)
Also, don't be afraid to saturate your roller with paint. Just roll off the excess in the shallow part of the tray so it doesn't drip on it's way to the wall. A saturated roller will mean fewer dips, a faster finish, and an easier time filling in textured walls.