If you want to paint trim in a carpeted room, you'll quickly find that nappy carpet fibres pose a problem. Carpet can't be protected with normal painter's tape, and painting near unprotected carpeting is tricky for even experienced painters. Paint shields, also called "paint guards" or "edge guards," are a good solution for protecting your carpet as you paint. Paint shields can add a little more time to the task.
Slide the long flat metal edge of the paint shield into the corner between the trim and the carpet.
Press the paint shield downward, into the carpet fibres. Your goal is to push back the fibres, leaving only the trim exposed for easy painting. The paint shield should be firmly jammed into the base of the trim, providing a tight seal between the trim and the paint shield.
Paint the trim using fast-drying latex paint and a foam brush. Foam brushes provide thinner coats of coverage, less likely to drip as you paint, further protecting the carpet from accidental paint splotches. Thin coats also dry faster than thick coats.
Remove the paint shield after the paint dries.
For a low-pile carpet, you may be able to remove the shield before it dries. In most cases, however, as soon as you remove the paint shield, the carpet fibres will touch the wet trim. The only way to fully protect the carpet is to keep the shield in place as the paint dries. A fast-drying latex paint dries in about 15 minutes, but the process is still time-consuming because most paint shields only protect a few feet of trim at a time. Blow-dryers or fans speed up the drying process.