1. Walls can have various types of problems, from pin holes and cracks to large break outs, to texture you don't want. Small things such as nail holes can be repaired with spackle, 'Dap 33' oil base window glaze, or tape & joint compound can also be used. Cracks between molding and trim can be filled with paintable caulk.
2. Most all repair jobs not done with spackle can be done with 'All Purpose Tape and Joint Compound' and 'Topping', both called 'mud', recommending USG or US Gypsum. Mud is usually held in a 'California Cake Pan' or small rectangular box about 4 x 12". Joint paper tape is used for all repairs. Never use mesh, as it is mostly air and will often crack. A roll of tape soaked in water is easiest for amateurs, sticks and flattens better, and is thinner the longer it is soaked. However it is more messy. Mud is applied in a straight line for the length of tape used, with preferably a 9 inch topping blade used for all operations. The tape is pressed into the mud completely flat and the excess is scraped off. This can be allowed to dry or a second coat can be applied immediately, so as to cover the tape.
3. This coat can be from 6 to 12 inches wide or wider. This then is allowed to dry overnight and usually a third coat of Topping is put over that. Tape can be of any length and should be overlapped about an inch when put together. All Purpose is structural, hard, shrinks and is more difficult to sand. Topping is finish, soft, doesn't shrink as much and is easy to sand, with 120 grit or sponge smooth. Sanding is best under enamel. Sponging raises no dust, but can show messy under enamel, but often good enough under flat latex.
4. Holes the size of a golf ball and smaller can be backed with some tight fitting plug or glued, something thin like can lid or simply taped over. Any rise caused by the patch can be feathered out with plaster, 12 or more inches all round. A patch is always taped over. Large holes are usually repaired with sheetrock of same thickness as what's there or thinner. For sheetrock walls: with a 'sheetrock saw' cut up and across and down & across to the stud in both directions. Cut down along the stud and remove sheetrock. With a razor-knife cut down at the center of the stud. Cut anew piece and screw to stud both sides. Tape all sides and feather. If there are no studs you can wire patch in. Fit a piece and drill two holes on four sides, one in the patch and one in the wall. Wire in, tape and plaster. For broken plaster over lath: remove loose plaster and cut a piece of sheetrock to the shape of the hole. Screw to lath and or studs. Plaster one does not want to remove can be secured with sheetrock screws and wide thin washers screwed into lath. All cracks are taped. You can also use USG 'Structolite', if you can find it, which can be put in thick. Scrape when dry, tape edges and cover with All Purpose and Topping. Always tape all edges in patching.
5. Cracks dug out and filled with plaster will crack again eventually. The best way to fix cracks is to cover them with paper sheetrock tape as described in Para 2. When taping curves like curved ceilings, use short pieces a foot to 2 feet long, overlapping a little at ends. Long pieces of tape on the curve will shrink and pull away from the wall. Patches do not need to be primed. Acrylic primer seals add a harder skin. However large areas like sheetrocked whole walls and rooms probably should be primed for toughness and seal to save on finish paint.
6. Textured, uneven walls, wall paper, plywood, even concrete block (best sealed) can be skim coated over to make smooth. For really deep rents or even making curves, use Structolite, which can fill up to four to 6 inches thick in one coat. Otherwise MSG 'All Purpose' can be applied and holds up pretty thick even up to an inch. Thick coats should be let dry before a second coat, so shrinking is completed. Anytime one removes by scraping ceiling or wall texture, one should first check to make sure it is not asbestos.
7. When patching, a problem is to match texture. Texture can be hard to match since it is usually machine blown. To texture patches, a stiff stipple brush will often do the trick, by sticking brush in plaster and stippling on finished and dry patch. If necessary, after it sets up a little, trowel over it to flatten high spots. Thick/thin plaster will give varying affects. Another method for large areas where called for is a little sand in the plaster. Drag blade flat across already dry patch. Of course one can use fingers, palms, sponge, rag or whatever to get the desired effect. This sort of thing can be practiced on a piece of sheetrock or plywood.
8. Lots of people use 'Fixall' and quick dry patch mixes. Fixall expands which helps to seal it in place. So if using allow for a hump. Gets very hard and needs electric sander to grind down. Unlike Structolite, Fixall sets up really fast so can mix only a little at time. Quick dry contains chemicals that can bleed through the paint, and thus require a coat of plaster, primer or 2 or more coats of finish. Thus it really doesn't save much time.
* Most quick dry patching compounds are difficult to sand. You should use standard wallboard joint compound for patching wallboard (drywall) or plaster.
* If the hole is doorknob size or larger, consider using the method described in Repair Holes in Drywall.
* To solve the 'hump' problem when using Fixall, wait for it to 'set up' a bit (but not fully hardened) and then 'shave' it with your moistened drywall knife.
2. Most all repair jobs not done with spackle can be done with 'All Purpose Tape and Joint Compound' and 'Topping', both called 'mud', recommending USG or US Gypsum. Mud is usually held in a 'California Cake Pan' or small rectangular box about 4 x 12". Joint paper tape is used for all repairs. Never use mesh, as it is mostly air and will often crack. A roll of tape soaked in water is easiest for amateurs, sticks and flattens better, and is thinner the longer it is soaked. However it is more messy. Mud is applied in a straight line for the length of tape used, with preferably a 9 inch topping blade used for all operations. The tape is pressed into the mud completely flat and the excess is scraped off. This can be allowed to dry or a second coat can be applied immediately, so as to cover the tape.
3. This coat can be from 6 to 12 inches wide or wider. This then is allowed to dry overnight and usually a third coat of Topping is put over that. Tape can be of any length and should be overlapped about an inch when put together. All Purpose is structural, hard, shrinks and is more difficult to sand. Topping is finish, soft, doesn't shrink as much and is easy to sand, with 120 grit or sponge smooth. Sanding is best under enamel. Sponging raises no dust, but can show messy under enamel, but often good enough under flat latex.
4. Holes the size of a golf ball and smaller can be backed with some tight fitting plug or glued, something thin like can lid or simply taped over. Any rise caused by the patch can be feathered out with plaster, 12 or more inches all round. A patch is always taped over. Large holes are usually repaired with sheetrock of same thickness as what's there or thinner. For sheetrock walls: with a 'sheetrock saw' cut up and across and down & across to the stud in both directions. Cut down along the stud and remove sheetrock. With a razor-knife cut down at the center of the stud. Cut anew piece and screw to stud both sides. Tape all sides and feather. If there are no studs you can wire patch in. Fit a piece and drill two holes on four sides, one in the patch and one in the wall. Wire in, tape and plaster. For broken plaster over lath: remove loose plaster and cut a piece of sheetrock to the shape of the hole. Screw to lath and or studs. Plaster one does not want to remove can be secured with sheetrock screws and wide thin washers screwed into lath. All cracks are taped. You can also use USG 'Structolite', if you can find it, which can be put in thick. Scrape when dry, tape edges and cover with All Purpose and Topping. Always tape all edges in patching.
5. Cracks dug out and filled with plaster will crack again eventually. The best way to fix cracks is to cover them with paper sheetrock tape as described in Para 2. When taping curves like curved ceilings, use short pieces a foot to 2 feet long, overlapping a little at ends. Long pieces of tape on the curve will shrink and pull away from the wall. Patches do not need to be primed. Acrylic primer seals add a harder skin. However large areas like sheetrocked whole walls and rooms probably should be primed for toughness and seal to save on finish paint.
6. Textured, uneven walls, wall paper, plywood, even concrete block (best sealed) can be skim coated over to make smooth. For really deep rents or even making curves, use Structolite, which can fill up to four to 6 inches thick in one coat. Otherwise MSG 'All Purpose' can be applied and holds up pretty thick even up to an inch. Thick coats should be let dry before a second coat, so shrinking is completed. Anytime one removes by scraping ceiling or wall texture, one should first check to make sure it is not asbestos.
7. When patching, a problem is to match texture. Texture can be hard to match since it is usually machine blown. To texture patches, a stiff stipple brush will often do the trick, by sticking brush in plaster and stippling on finished and dry patch. If necessary, after it sets up a little, trowel over it to flatten high spots. Thick/thin plaster will give varying affects. Another method for large areas where called for is a little sand in the plaster. Drag blade flat across already dry patch. Of course one can use fingers, palms, sponge, rag or whatever to get the desired effect. This sort of thing can be practiced on a piece of sheetrock or plywood.
8. Lots of people use 'Fixall' and quick dry patch mixes. Fixall expands which helps to seal it in place. So if using allow for a hump. Gets very hard and needs electric sander to grind down. Unlike Structolite, Fixall sets up really fast so can mix only a little at time. Quick dry contains chemicals that can bleed through the paint, and thus require a coat of plaster, primer or 2 or more coats of finish. Thus it really doesn't save much time.
Tips
* Most quick dry patching compounds are difficult to sand. You should use standard wallboard joint compound for patching wallboard (drywall) or plaster.
* If the hole is doorknob size or larger, consider using the method described in Repair Holes in Drywall.
* To solve the 'hump' problem when using Fixall, wait for it to 'set up' a bit (but not fully hardened) and then 'shave' it with your moistened drywall knife.
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