painting
I bought some standard American Craftsman screens (Anderson) from Home Depot. The frame is aluminum and white.
I'd like to paint the frame to match the wood trim and vinyl door frame.
How should I prepare the surface for painting so the paint adheres properly and should I buy a specific type of paint?
If you must paint this stained wood, a light sanding with 4-O steel wool or 320-grit sandpaper should be fine. All you're doing is roughing up the surface coat, usually poly, which will let the paint "key" to the surface better.
Be aware of the finish originally used on the wood; only poly will take a latex topcoat well, while on most other finishes like varnish or oil-based finishes, latex will not bond to the surface properly; it may peel easily, or even bead up when applied. If this is the case, roughing up the topcoat is not enough; you will have to sand off the topcoat to get to raw wood, and on a profiled wood piece like mouldings, this can be difficult or impossible.
Also be aware of the type of wood; certain woods are "open-grain", and will absorb paint deeply into the structure of the wood, requiring many coats to "fill" the wood and get a solid color on top. Otherwise, the grain and any knots will show through the final coat until you put 3 or 4 thick coats on. If you have to go down to bare wood on an open-grained wood, you have to seal the wood with a product that is compatible with your paint base.
Sounds reasonable to out-source it, but you will still need to do a final coat on the casing after you install (door should be fine if you are careful).
To "do it right", you need to fill the nail holes and corner joints and sand, and then run a bead of painters caulk around the casing to make the cracks disappear, then paint again.
I just did the caulk on the inside (casing-to-jamb) not the outside (casing-to-wall), and didn't paint very far onto the side of the casing where it hits the wall. This way, you get a nice sharp line at the wall without a lot of hassle.
Best Answer
Scuff-sand the surface to remove gloss and create a micro-jagged surface (aka "tooth") the new paint can engage to.
For exterior doors my first choice is a marine LPU, but unless you paint boats (know anyone?) the cost of hardener, reducer, and other kit is prohibitive.
So I recommend a quality alkyd enamel ("oil paint"). Brush it unless you are setup to spray, get throwaway bristle brushes. Enough coats so the old color doesn't punch through.
Start with a wipedown with the paint's solvent to remove dust and surface contamination.
To buy the paint, either use a Rustoleum stock color (beware, some Rustoleum is latex), or go to a Sherwin Williams industrial outlet who can custom match and give you quarts. A more hooty-tooty brand is Fine Paints Of Europe.