Plastic knives are inexpensive, but they are also weaker and more disposable than metal ones. If you’re planning on using the knife often, get a stainless steel one instead. For most projects, a 3 in (7. 6 cm) blade works well. You could use a 4 in (10 cm) blade to fill in bigger areas or switch to a smaller blade to fill smaller holes.
Note that many products, including wall putty, have to be mixed with water before they can be applied. Check the manufacturer’s instructions about how much water to use. Dry products that don’t have to be mixed, such as window glazes, can often be applied by hand. Set it where you need to spread it instead of trying to pick it up with a knife.
If you’re working on a gap larger than a nail hole, spread putty around its edges first. That way, you will have enough putty to spread over the entire gap.
If you used too little putty earlier, scoop up a little extra and apply it above the hole. Make sure you use a little bit at a time to keep the layer of putty consistent. Before beginning, spread some of the putty along the top edge of the area by moving the knife from right to left. This will help you distribute the putty more evenly while you’re moving the knife down the wall. If you’re working on a nail hole, use the tip of the knife to force some putty into the center of the hole.
Note any areas that look rough or uneven. Scrape off the excess putty this way before it has a chance to dry.
Putty dries after about 4 hours. Some products may be different, so consult the manufacturer’s recommendations to make sure. In some cases, you may need to apply additional layers before the fix looks complete. Remember, you are always better off using sparing amounts of putty than adding too much all at
You could use a 1 1⁄4 in (3. 2 cm) knife for most projects. The size isn’t as important as getting a quality knife. Get larger or smaller blades according to your project. If you’re scraping down a wide area, finish it faster with a bigger knife. Use a smaller one if you need to get into tight areas.
You may also wish to wear safety goggles and gloves to protect yourself from chipped material coming loose while you work. It usually isn’t necessary unless you suspect you’re dealing with something toxic. If you think you’re scraping a toxic material like lead paint, get it tested first. Purchase a lead-testing kit, swab some of the paint, then remove it safely.
For example, if you see empty spots from peeling paint, you can start there. The space left by the peeling paint gives you some room to move the knife. Some other places to use the knife include underneath peeling wallpaper or underneath the edge of a loose tile. If you’re evening out a finish, such as with wall putty, look for spots that appear uneven. You can also feel for rough or uneven spots by hand.
Make sure the chiseled edge is face up so it cuts into the surface material. If it is face down, it may scratch something you don’t plan on scraping off.
If you are unable to remove all of the material, approach it from different sides. Readjust the knife’s positioning while keeping it at a 30-degree angle. Always move toward the loose material.
