How to Varnish an Interior Wood Door

Whether you have a new interior wood door that you plan to stain, or whether you have an existing one you have already stained, you will want to add a protective coat of varnish to complete your project. This additional step will not only protect the door's surface, but will add an attractive glossy finish. To varnish your wood door, follow the steps below.

Items Needed:

  • Varnish
  • Paint brush
  • Clean cloth
  • Sand paper (fine grade)

Step 1 – Apply in Appropriate Temperature and Humidity

When applying varnish it is important that the temperature of the surface you are painting, the temperature of the varnish, and the temperature of the room in which you are painting are all between 70 and 80 degrees. These temperature factors are all necessary if you want your varnish to be smooth and to dry properly on the surface of your door. If your varnish has become chilled before you are ready to use it, warm it by placing it in a pail of very hot water. Be sure the lid is tight before placing it in the water.

Most varnishes should be applied in normal humidity conditions. If you plan to apply varnish in a higher than normal humidity level, you should plan to use a varnish that can be applied in these conditions. Otherwise, excessive humidity can often present problems with the varnish.

Step 2 – Use Adequate Ventilation

When applying varnish it is important that you do it in an area where there is adequate ventilation. Good ventilation is necessary in order for the varnish to harden sufficiently and for you to avoid breathing fumes that might be noxious.

Step 3 –  Apply Varnish Over Dry Stain

Before applying varnish to your stained door, make sure that the stain on the door has completely dried. Wipe the door off with a clean cloth to remove any debris, so that your varnished surface will have a smooth finish.

Step 4 – Mix Your Varnish

It is important that you stir your varnish thoroughly before applying it. This will help mix sediment that has collected in the bottom of your can. Avoid shaking the can to mix the varnish. Shaking can create air bubbles on the finished surface and make the surface rough.

Step 5 – Use a Quality Brush

When using varnish it is important that you use a high quality paint brush that will prevent runs and lines from forming in your finish. Apply the varnish to your door in long, even strokes in the direction of the wood grain.

Step 6 – Allow to Dry

Allow the first coat of varnish to dry overnight. It must be completely dry before you begin sanding.

Step 7 – Sand Your Varnished Door

Once the door has completely dried, lightly sand it with fine sandpaper until you have a smooth surface. If, when you begin to sand, you find that you are producing little balls of varnish, you should allow the door to dry longer before continuing. 

Step 8 – Complete Your Project

After your varnish has dried, and before applying your next coat, use a soft clean cloth to remove any dust particles. Repeat Steps five through eight until you have the finish you desire.