Painting and Stripping Old Wood Siding
Step-By-Step

Strip the old paint using an infrared paint stripper for large areas and a heat gun for hard to reach areas.
More information on our paint removal page.

Remove any caulk between the boards of the siding. In old houses, caulking between boards will trap in moisture that can cause the paint to peel.
In the photo on the right, you will see wooden plugs use to cover the holes drilled to blow in insulation. We reset all of the plugs by removing them, applying polyurethane glue (Gorilla Glue), and resetting them in the siding so that they were flush. This was preferable to filling in recessed plugs with filler which might develop small expansion cracks around the plug's circumference.

Using an infrared heat paint stripper

Nail any loose boards. We removed the old cut nails from 1860 because they no longer gripped well. We replaced them with stainless steel siding nails.

Sand. We used a palm sander with course 40 grit cloth backed sand paper.

Patch any surface holes with an exterior wood filler. We used Dap Wood Dough for small holes and surface cracks. Time will tell if this filler holds up, in the past other we have tried didn't. Fill any large holes with an epoxy filler (See below). Epoxy filler has the same expansion properties as wood and doesn't shrink when it cures.
Do a final sand with course 60 grit cloth backed sand paper.

Because older wood framed homes are not rigid, wood fillers can work loose over time. For this reason, we were careful to use the epoxy filler on large holes and to caulk thin cracks using the flexible, paintable silicone caulk.

Note: Use an epoxy filler designed for use on wood (two are recommended below) so that it will have the same expansion characteristics as the siding. We don't think it is cost effective to use cheaper auto or marine epoxy fillers.

Apply a coat of wood preservative on any wood sections not coated with the liquid epoxy. We used Wolman's Zinsser Woodlife Classic. To use a preservative, the siding must be free of paint so that the preservative can be absorbed by the wood.
Use an epoxy consolidant instead of the preservative where the wood is soft (See below). We painted all of the the window trim using the epoxy consolidant as this provides the best water protection and paint bonding. The epoxy consolidant is too expensive to coat all the siding.

We have also learned of Smith and Co's epoxy primer, MultiWoodPrime

Note: Be sure to paint on the epoxy consolidant before painting on the wood preservative. Don't bother to use the preservative on any painted or epoxy consolidated wood. It won't be absorbed.

Paints containing linseed oil are very susceptible to mildew. Of the available water-base paints, acrylic latex is the most mildew resistant. Porous latex paints applied over a primer coat with linseed oil will develop severe mildew in warm, damp climates.

Apply one coat of alkyd primer. We used to use Benjamin Moore Fresh Start Penetrating Alkyd Primer 100).
We are now using ZINSSER H2OIL-BASE® primer as it dries faster and looks like it has better properties than regular oil based primers.

Tip: Have the paint store tint the primer to the same color as the top coat.

• Don't let the primer sit more than a few weeks before painting. Soap-like compounds can form on oil primers in as little as two weeks.
• Use a brush when painting old siding. It allows the paint to be worked into the siding's imperfections more effectively than a roller or spray.
• Don't prime or paint in direct sunshine, when it is dry and breezy, or is very hot (over 90 degrees F)
• Paint should not be applied when the air temperature is below the stated figure for the product, nor if the temperature is forecasted to drop below that minimum during the next 24 hours, nor if the surface being painted is below that temperature: Oil-based paints should be applied when the temperature is at least 40 F; for latex paints, the temperature should be at least 50 F.
  When pretreating the wood with a paintable water-repellent preservative (a recommended practice), best results are achieved if it is applied when temperatures are greater than 70 F.
• Don't paint if it is too humid (between 20% and 80% is ideal). When water-based paints cure, the water should evaporate as fast or faster than the solvents. After the water has evaporated, the paint will shrink to nearly its final shape. As the solvents evaporate, the paint chemically reacts to form a hard material. When it is too humid, water cannot evaporate and the solvents may evaporate first, causing the paint to cure while still in a water-filled state. You cannot recover from this type of disaster. Oil-based paints will also fail if conditions are too humid.