Before you paint anything, you must properly prepare the surface no matter the material. Professional painters know this and know that taking the time to prepare surfaces will help the paint to look better and to adhere longer. If you're going to be painting the interior or exterior of your home or anything else, note a few simple but very important tips for preparing the surface.
1. Wash Thoroughly
Use a good cleanser but one meant for the particular surface before you do anything else. For aluminum siding, use a detergent meant for homes. For an outside deck, use a cleanser meant for wood. Metal also needs to be cleaned thoroughly before painted.
2. Remove Rust
Rust flakes off and if you try to paint over it, this will only result in having the paint flake off with it. Rust is also rough and will make the paint look bubbly. It's vital that you remove rust from any metal before painting; this can be done with sandpaper, a spray coating that will cause the rusted pieces to flake off, or with sandblasting.
Sandpaper can work for very small items but can be time-consuming and cumbersome for larger objects, and may not allow you to get into cracks and crevices. Spray coatings can also be harmful to your health if you breathe in the vapors. Sandblasting can be used for a thorough cleaning and removal of rust at the same time, and will get into grooves, cracks, and other areas otherwise unreachable.
3. Rough up the Surface
Paint can't actually adhere to a very smooth surface, as it may simply slide off. It's often necessary to rough up a surface that is very smooth. When painting wood, this can mean using a fine grit sandpaper to make the surface more hospitable to paint. You don't want to make it so rough that the paint won't look smooth but if you paint a smooth surface, you can typically just peel the paint away in one large piece.
4. Choose Another Form of Coating If Necessary
Since paint doesn't adhere to very smooth surfaces, you may want to choose another form of coating for metal and other such materials. Powder coating is a popular choice; this refers to a type of powder that is applied to the surface and which dries to look just like paint. This powder works better on metal surfaces and because it's sprayed on rather than brushed or rolled on, it fills in cracks and grooves in metal. Note if another form of coating is necessary for your surface once it's prepared, for a better finish that lasts longer.