The difference between a small painting job and a big painting job is the prep time. Preparation is the bane of existence for lots of DIYers because they don't expect it to be so time-consuming. You can easily devote an entire day to masking, filming, tarping, and taping--all before even cracking open a single can of paint.
Painting by hand, you can, in theory, mask off areas at your own discretion.
While it's not recommended, you can paint an entire room with brush and even roller without spilling a single drop on the floor or furniture. But when you use a paint sprayer, you absolutely have to mask off areas that will not be painted because overspray is inevitable.
To mask a window or two, you can always use newspaper and masking tape. But for anything more than that, you'll make your life easier if you use masking film.
What is Masking Film?
Masking film is not the same thing as tarp. Tarps are not meant to be form-fitting or to create a paintable edge. For walking on or for covering items, consider using a canvas dropcloth.
Masking film comes in long rolls (i.e., 25m or 33m.) of widths from 550mm to 2400mm. You will find two types of masking film:
The first kind is called Pre-taped masking film or Masker. It is represented by KIKUSUI Masking Adhesive Tape & PE Pre-folded Masking film roll and has a strip of adhesive painter's tape running along one edge of the film.
The second kind is called Pre-folded masking film, has no tape, relying instead on the plastic's static-cling properties to hold it in place. Run masking tape along any edge you will be painting next to.
How to Get the Right Size of Pre-Taped Masking Film?
Pre-taped film combines two steps: taping and draping (it should be noted that you may need to tape the other three edges separately).
Remember, too, that bigger is not always better. Using oversized masking film doesn't just result in waste--you also need to cut or tape up all of that excess, which can be a pain when dealing with this extremely thin film that always wants to cling to your hands and arms.
Where to Use Masking Film?
Interior Walls: A classic way to use masking film: when painting a ceiling, run the adhesive edge along the top of the wall, unfold the film downward, pressing it flat against the wall. Then begin to paint.
Windows and Doors: Masking film works great on windows because it sticks well to glass. Masking film will rarely match the exact size of windows and doors. But all you need to do is run the adhesive strips down two sides of the area to be masked. If you have at least 150mm of overlap, it's not necessary to tape between the two sections (though it can never hurt).
Other Areas: Remember that masking film isn't just for painting right to the edge. Often, you need to cover cabinets and flooring to protect them from ambient spray. Masking film works great for this.
Sanding: Masking film is perfect for particle-collection. Unlike plastic tarps, masking film's static-cling almost magnetically pulls paint and dust particles toward it.
Large Areas: If you have large areas to mask, it's nearly impossible to use newspaper. Masking with masking film consumes far less time than masking with newspapers because, with film, you're only dealing with a single sheet of film. With newspapers, it can take 5 or 6 sheets to properly cover a window or door.