Paint tins are designed to provide a tight seal. If even a little bit of air gets into the tin, the paint drys out. The tightly fitting lid is practical, but it poses problems for a novice painter. Some DIY shops even provide free lid openers with the paint. But if you're never opened a tin of paint before, this specialised tool doesn't help much. Fortunately, the process isn't overly complex. With just a little bit of background knowledge, it's possible for virtually anybody to open a tin of paint with a minimum of mess.
Lay a canvas dust sheet or some sheets of newspaper across a flat work space. The underside of the paint tin lid is likely covered with a layer of wet paint. This paint may drip as you remove the lid, and you need to protect your workspace from paint splatter.
Place the thin tip of your paint opener into the seam between the tin's lid and the container's sides. You want the small "hooked" part of the opener to be curved toward the lid. If you do not have a paint opener, slide the tip of a flathead screwdriver into the seam.
Rotate the paint opener downward and away from the paint tin. You're trying to pry off the lid now that the opener is lodged in the seam between the lid and container. Pry using the screwdriver in the same fashion. Don't worry if the entire lid doesn't pop off. Just pry up as much of the lid as possible.
Move the paint opener or screwdriver about 6 cm away from its original position and then repeat the same process.
Continue to move the opener along the can's lid, prying up the lid in 6 cm increments. As you move around the can, small gaps open up along the lid. You've finished prying off the lid when it is visibly loose and no longer attached to the main paint container.
Hold the sides of the lid and lift it off the paint tin. Set the lid face up on the protective cloth or newspaper. When you've finished painting, reattach the lid by setting it on the container and hammering down the edges. Do not hammer the middle of the lid; just focus on the outermost edges.