There are many variables to consider with regarding to new paint projects and touching up previous paint projects, so it is very important to understand the importance of proper prep and storage of paint. Please read the following to be better informed so that you will get the best results:
(1) Even if you are hiring a professional painter, always read the instructions on the can label and make sure your surfaces are prepared properly by following the surface prep instructions on the label. Surface preparation is everything to ensure a good paint job. I have been amazed by how many painters try and cut corners by not following proper prep instructions and not waiting the proper length of time between coats.
(2) Always purchase enough paint so that you will have leftover paint for touch-ups. Also, it is extremely important that you store leftover paint in an airtight container in a climate controlled environment as heat and cold affect both the color and usability of the paint. See "Touch-up Tips" below.
(3) Rolling walls and ceilings are much better than spraying because it creates a tougher surface which cleans up better. This also will affect how well the paint can be touched up at a later date. At the very least, make sure your final coat is rolled on. A minimum of two coats creates not only a prettier finish with more depth, but it is also more durable. See "Touch-up Tips" below.
(4) When using latex paint, be sure you are painting over latex, not oil. Test a small area by rubbing it with a rag soaked in isopropyl alcohol to see if any paint comes off. Latex paint will come off, not oil.
(5) If painting over oil, an oil-based primer that is an interface between latex and oil is A MUST. Otherwise, the paint will not stick. Now they make "no odor" oil-based primers, like Kilz Green Start.
(6) The glossier the paint finish, the more imperfections on the wall surface will be highlighted. Flatter paint finishes hide wall surface imperfections and are also easier to touch-up. Although finishes like eggshell and semi-gloss are physically harder, they are also visually harder and if your walls are textured they won't have the "atmospheric" appearance our washable flat paints do. However, we highly recommend our Lifemaster Eggshell which has a very low sheen and is easy to clean, if done properly.
(7) Do not use deep colors in high traffic areas, as they tend to burnish easily. That said, for deeper colors, plan on three coats for the best coverage and use a tinted primer. (We offer full-spectrum tinted primers.) Do not use gray tinted primers (which are often recommended by painters and paint stores) as they will dull the color. Also, be sure to use eggshell, NOT flat in high traffic areas, kitchens and bathrooms.
(8) Stir the paints very well before each use as they contain numerous pigments that need to be blended.
(9) Use the best quality rollers and natural bristle brushes.
(10) Do not apply paint too thick and be sure it has plenty of time to dry between coats. Failure to do so, may result in paint crackling.
(11) To hide switch and outlet plates, first spray them with Kilz which comes in a small spray can (about $4) and then paint with wall paint. The Kilz helps to keep the paint from wearing off.
(12) Never store paint in areas where they are exposed to extreme temperatures. Our paints have a one year unopened shelf life. We recommend storing left over paint in air-tight jars indoors in a cabinet or closet along with small sponge brushes for touch-up. See "Touch-up Tips" below.
(13) When cleaning painted surfaces, use only Ivory Liquid Soap or Murphy's Oil Soap and a VERY soft rag. Other cleaning products may contain alcohol which will mar the painted surface. However, paints need several weeks to cure before cleaning. Be gentle when washing so as not to burnish the finish.
How to Touch Up Flat/Matte Finishes
Paint touch-up is a common source of problems due to so many variables that affect touch-up, from the age of the original paint job to whether or not the same paint used on the project is stored properly, temperature changes between coats (within 5 degrees of original application temperature), and even different application methods (brushing, rolling or spraying). However, if done correctly, touch up should blend in acceptably with the surrounding painted area. Best solution is simply to repaint the wall from "break to break" (i.e. any place where a section of wall ends).
(1) Number one rule. Never touch up matte paint until it has dried for 24 hours. To make it less noticeable, wait for 2 days.
(2) ALWAYS use properly stored leftover paint to touch up with. The key to paint storage is keeping air out of the container, so we advise pouring leftover paint into an airtight container (we use mason jars), filling it so that there is as little air to the top as possible. Applying a little petroleum jelly to the inside lid threads helps with lid removal later.
(3) Applying as thin a film as possible is often the best approach and in some instances, thinning the paint with a little water may help. You want to use the least amount of paint necessary to achieve the least noticeable touch-up. As you approach the edges of the area, almost wipe the brush dry and feather the paint out. Small foam brushes and artist brushes make the best touch-up tools, as it is always best to touch up just the marks or dings on the walls if not going corner to corner.
(4) Sources we used for this page are well worth the read: