All products made out of wood, especially wood doors, are susceptible to the elements. Extreme temperature changes, moisture, and humidity can all damage wood. When a wood door is left unsealed, it will soak up any of the excess moisture in the air which will cause wood doors to swell and warp. The following article will show you how to properly seal your wood doors from the elements.
Step 1 - Prepare
Place the drop cloth on your work area floor then put the sawhorses on top of it. Remove the wood doors to be sealed and place one on top of the sawhorses. Remove the door knob and hinges using the screwdriver. Never try to seal wood doors while they are attached to the frame because you will never be able to contain the drips or spills that may hit the floor. Use the sandpaper to sand down the door. You need to sand the door, even if it is brand new, to remove handling marks and to open the wood door's pores so it will soak up the sealer and the stain. Use a textured and rough grit to remove damage. Follow with sandpaper that is very fine to smooth the wood. Use a damp rag and tack cloth to wipe down the door to remove sanding dust.
Step 2 - Apply Wood Treatment
After you are finished sanding and wiping down the wood door you need to apply a sanding sealer. This type of wood treatment is more important for soft woods and species that do not evenly absorb sealer. Apply the sanding sealer with a brush that has soft bristles because it prevents discoloration as well as blotches as you proceed with sealing the door. Allow the wood treatment to dry before you continue with sealing the wood door.
WARNING: Check the wood treatment's container before starting work to see if it has any chemicals that are toxic to breathe in. If so, wear a face mask while applying it.
Step 3 - Stain
If you choose to stain the wood door you want to use a stain that is intended for exterior use and that is also UV protected. Do not use combination stains or sealers on wood doors because they do not offer the protection that you need and you will have to use another product to seal the wood. When you have the stain you need you will use the foam brush to paint it on the door. Make sure you go against the grain. Use a rag to wipe the stain downward along the flow of the wood grain. Wipe off the excess and allow it to dry before moving forward.
Step 4 - Seal
You are almost done, the only thing that is left to do is to seal the door. Just like with the sanding sealer, check the ingredients to see if the polyurethane has any safety instructions, and follow them carefully. Use a clean brush to apply the polyurethane with the grain. When the polyurethane dries (which should take 1 to 2 days) you should inspect the door by feeling its finished texture which should feel slightly rough. This texture confirms that the sealer did its job. Use a very fine grit sandpaper to remove the rough texture and a damp cloth to wipe it down. Attach the door knob and hinges and hang the door.