When it comes to painting doors, the only way to do the job right is start off with complete removal of the door itself from the frame. Trying to sand, prep and paint a door when still connected to the wall frame is just asking for a lot of headaches, a big mess, and probably more work doing additional repairs.
With the door disconnected, all the hardware needs to be removed as well before paint door stripping. The handle tends to be pretty easy; once the securing screws are removed, the assembly will generally wiggle and fall out. The remaining tongue and hinges can be removed when their securing screws are taking out as well. The door can then be placed flat on construction horses or a table for the work phase.
Now the door can be treated. The first step in paint door stripping is to sand. While one could use a chemical peel like Jasco or similar, it’s a bad idea as the chemical stripper could soak into the wood below and then affect future paint from adhering properly. That leaves sanding. This is at least a two-step process: a rougher grit to remove the paint effectively and a fine grit to smooth out the surface to a flat sheen. When the sanding is complete, The door should be completely brushed to remove all dust, and then wiped with a moist cloth to capture any remainder. Now the stripping is complete.
In terms of paint, the first layer should be a primer that will soak into the wood and create the optimum paint bed for the outer coat. If you are going to choose a primer-and-paint cover, then make sure it’s a top quality one. Lower quality combo primer/paints often require more than one coat to be applied to get a thick finish.
Keep in mind with the final paintwork, you will need to choose a paint type. Matte, egg shell, semi-gloss and gloss tend to be the common choices. Semi-gloss and gloss are frequently the best for doors which get a lot of contact from hands, leaving prints and dirt. With the gloss feature, the traffic prints can be wiped right off. Matte paint tends to absorb the prints and ends up having to be repainted for a clean look. The smoothest paint finishes for doors tend to be spray-painted on with an even layer versus brush work. No matter how hard one tries, brush applied paint will still show a mild brush-stroke pattern versus a clean flat surface.
If using a stain for a door surface finish instead, the door should be cleaned all the way down to the bare wood surface as described above. Any kind of paint residue is going to prevent the stain from absorbing into the wood properly. Staining also often takes multiple coats to produce a rich color and finish. So take your time when applying and don’t rush the job. And, when done staining, a urethane layer often needs to be applied as an outer clear-coat for protection.
Try to work one side of the door first, finish and dry properly, and then the other side. This will allow the best finish and reduce smudges and pressure prints on the new paint or stain. When complete, re-install all the hardware and remount the door in it’s frame. Make sure the door is balanced or it likely won’t shut correctly. Once the job is complete, it’s time to congratulate yourself and think about which door will be the next one on your home improvement restore list.