Fixing textured (not popcorn) drywall ceiling
If you've got a house built in the 90's, you may well have a textured drywall ceiling with a pattern on it. The most common pattern is a blossom texture with patterns of repeating ridges form circles.
The problem comes when you have to repair this ceiling. Knowing how to duplicate the texture is the problem.
Here are the steps to do this:
Replace/repair drywall ceiling until the surface is paint ready, but do not paint. Sand texture off of some of the adjoining ceiling to avoid a visible border.
Make sure you have a drop cloth down!!! This might drip.
Mix drywall mud down to the consistence of pancake batter. You want it stiff enough not to drip, but pliable enough to texture. The mixture should just barely be pourable.
Pour into a paint roller pan, and using a long nap roller with the lint removed (use masking tape) roll the joint compound onto the repaired area.
Allow to set for a few moments to make sure it won't drip Now get out your stomping (yeah, that's what they call it) tool, and texture the ceiling.
You can buy brushes to "stomp" your ceiling at many paint stores, but they aren't cheap. Instead, you can do what most drywall guys do, and make your own. Go to the store and get an old fashioned string mop. When selecting the mop, look at the head. Some have a rectangular bar holding the strings in place, and some have a round tab, about the size of a quarter. You want the one with the round tab, and get one with strings, not cloth strips.
When you get it home, hold the mop up to the ceiling, and note how long the strings need to be to create the same size pattern. Cut your strings about two inches longer, since the whole string does not hit the ceiling.
Trim the strings to the correct length, then soak the mop for 24 hours to limber them up.
Now back to the stomping. Once you have your drywall mud applied, all you have to do is hold the mop over your head, upside down, straight up, with the strings hanging uniformly around the sides. The mop should be damp, but not wet. You can add a bit of drywall mud to it first if you wish, I do not.
Hold the mop about eight inches below your drywall, and starting at an edge where you can judge where to match the old pattern, "stomp" the mop into the wet mud, just like you were stomping your foot. Immediately pull the mop back, and you should have the same pattern as your ceiling.
Continue stomping until you've covered the ceiling. Afterward, you can wash the mop, and keep it for later if you think you will need it.
After stomping, let it dry for at least two days before painting.
When you buy your drywall joint compound, look at the prices. You can often get a five gallon bucked for only a couple of dollars more than a gallon. (I always buy pre-mixed, it works great). To preserve the mud you didn't use, after you're done with it, mix a teaspoon of bleach into a cup of water. Level the surface of the mud in the bucket, then pour a layer of the bleach/water mix on top. This will keep the mud from drying or molding.