The trick is to remember: “The wall GETS BIG!” I tell my painters this all the time and it’s a good way to remember where to put the line. So whether you’re gluing the wall to paint the ceiling or brushing the top of the wall next to the ceiling, you want the wall color to be just a little higher than the wall actually is.
In application, this means you barely get the tape through and I mean barely touch the ceiling if you are preparing to spray the ceiling and masking the walls. Or in case you are brushing the top of the wall, you want to cut the line so that the wall color touches the ceiling but without the wall color hitting the ceiling. With practice, it becomes a very quick and efficient way to cut through the roof.
The reason for this has to do with how your eye perceives this transition from a distance. The wall is the focal point and so if that color barely touches the ceiling, you don’t really notice it. On the other hand, if the white color of the ceiling barely touches the wall, it sticks out like ketchup on a wedding dress! This technique allows you to maintain a good speed with your brush and also leave a nice appearance.
The same is true for cutting lines on baseboards and window/door frames; the wall grows large. Now when it comes to an eye level door or window frame, you might want to use tape to help make a nice clean straight line here, but using the same strategy of the wall color that barely reaches to the molding
So I hope this tip helps you realize that you don’t always have to split the line in exactly the right place if you make sure you put it on the right side. This technique can be applied in many different situations if you understand that whatever the focal background is must GO BIG!
Don’t be discouraged if it takes you a while to get the hang of cutting or tape. Cutting can be difficult to master at first, but it will save you time in the long run because you can skip curbing altogether. Good luck!