How to Paint the Knots in Knotty Alder Doors

Painting Alder doors, or any previously stained door requires careful preparation to achieve a flawless and beautiful paint finish. Alder doors contain several knots, which often hold tannin, sap, and stain from the factory finish. Painting over Alder door knots---without preparation---allows tannin and old stain to bleed through the newly painted surface, ruining the finished product. Depending on the amount of doors you need to paint, you can easily prepare and paint door knots in as little as one day.

Drop cloths
Cardboard
Painters tape
80-grit sandpaper
Oil-based primer sealer
Empty bucket
Paint screen
4-inch roller (1/2 inch nap)
4-inch handle

Instructions

- 1
  Protect the work area. Place drop cloths on both sides of the door, or place a large piece of cardboard underneath the door. Wrap blue painters tape around the door knob.
- 2
  Sand each door knot, using 80-grit sandpaper. The sandpaper penetrates the previous stain and door varnish, and opens pores in the wood for priming and painting.
- 3
  Pour on gallon of oil-based primer sealer into a clean empty bucket. Stir the primer thoroughly, using a stir stick. Hang a metal paint screen on the inside of the bucket.
- 4
  Insert a 4-inch paint roller onto a matching handle. Use a 1/2-inch nap roller for ease in applying the primer.
- 5
  Lightly dip the Whizz roller into the Kilz primer bucket and roll off excess material onto the paint screen. Do not dip the roller deep into the bucket.
- 6
  Prime each knot with the first coat of primer. Apply generous amounts of primer, but do not leave drips or heavy build-up on the surface. Remove excess primer, by rolling over the primed surface a few more times.
- 7
  Allow the first coat of primer to penetrate and dry for two hours. Inspect each knot for bleeding resins, tannin or stain. Apply a second coat of primer, if necessary. Once the knots appear solid---without any bleeding resins---the entire door can be finish painted.

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