Whether you are painting the exterior or the interior of your historic house or building, you want the finished job to look great — and to last a long time. The advice offered below will help you achieve those goals.

Follow Best Practices

Preservation best practices for painting require a thoughtful approach to maintaining or repainting originally painted surfaces. To retain the character of your historic structure, you must maintain the original shellac and varnish finishes or use a replacement finish that matches the original finish. You should never paint any previously unpainted surfaces in your historic house or building.

As a rule, you should never paint unpainted bricks, stones, stucco or concrete. If your brick structure has been painted for a long time, the paint was probably applied to cover a problem with the bricks. The bricks may have been soft and deteriorating, or they may have been sandblasted at a time when this was popular. You should hire an experienced mason to determine whether the paint can or should be removed. If the bricks must be painted but need a fresh paint job, be sure to repaint them with a product that has high vapor permeability. These products are available through masonry supply companies.

Use the Right Products

You have many paint and primer options to choose from, so do a little homework to make certain you select the best paint for your house or building. Here are some tips to help you make this decision:

• Use a liquid paint splatter removal product to determine if your existing paint is latex or oil. The paint splatter removal product will remove the paint if it is latex, but it will have no effect if it is oil paint.
• Never apply oil-based paint on a surface painted with latex paint. This practice will create compatibility issues due to the different curing process of each type of paint. However, you CAN apply exterior latex paint on a surface painted with exterior oil-based paint.
• Use an alkyd oil-based primer. These primers penetrate into old exterior wood better than latex paints, and you can apply latex top coats on the alkyd oil-based primers. For even better penetration into old wood, add 1/8 cup of boiled linseed oil to each gallon of alkyd oil-based primer.

Prepare the Surface Properly

You can take measures to prevent paint failure by properly preparing the surface to be painted. Here are a few surface preparation tips:

• Use a moisture meter to check the moisture content of any wood surface you plan to paint. Wet wood will not hold paint, so you should not paint any wood with a moisture content greater than 15%. You can buy a moisture meter at a paint store or lumberyard.
• Assume that the old paint in your historic house or building contains lead, and follow procedures for the safe handling and removal of lead paint.
• Never dry scrape any old paint. Mist the wood with water first to prevent the spread of lead dust.
• Use a paint removal device that is adjustable and verify that the operating temperature is kept well below 650 degrees Fahrenheit — the temperature at which lead paint becomes a toxic vapor. Infrared paint removal tools will not heat the paint over 600 degrees and are approved by the Environmental Protection Agency for safe lead paint removal.
• Sand off the shiny gray layer on a wood surface before you paint it. This graying is deterioration is caused by exposure to sunlight.
• Clean and lightly sand or de-gloss oil paint before you apply interior latex paint over any glossy interior oil paint.
• Do not use hard fillers to fill exterior nail holes. Use linseed oil-based glazing compound to allow the wood to expand and contract.
• Always prime before you caulk. Dry wood absorbs the oils in caulk, causing the caulk to shrink and fail.
• Only add exterior caulk in locations where cascading water can enter a joint.
• Apply exterior paint on window sashes so it extends 1/16 inch onto the glass to seal the glazing compound.

Use Effective Painting Strategies and Techniques

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For best results, always paint in the shade. When paint dries too quickly it can bubble leading to a poor end result. Source: Bob Yapp

To ensure your painting efforts will be effective, follow these strategies and techniques:

• Never paint outside when the temperature exceeds 90 degrees Fahrenheit or when the temperature will not reach 50 degrees for 24 hours.
• Never paint outside in direct sunlight. Direct sunlight creates excessive heat and can cure the paint too quickly, causing paint adhesion problems.
• Never paint outside when the humidity level is over 80%. High humidity creates excessive moisture on the surfaces being painted and can prevent the paint from adhering properly.
• Never apply oil paint when the temperature exceeds 90 degrees or when the temperature will not reach 40 degrees for 24 hours after painting.
• Never apply latex paint when the temperature exceeds 80 degrees or when the temperature will not reach 50 degrees for 24 hours after painting.
• Never spray paint wood exteriors. Spray painting provides less surface adhesion and paint thickness than brush painting.
• Remove painter’s tape as soon as the paint is dry. Blue and green painter’s tape that remains on a painted or natural finish surface for over a week will damage the paint or finish.

Clean and Maintain Painted Surfaces

Your painting job is not done as soon as the paint dries. Follow these practices to clean and maintain the painted surfaces in your house or building:

• Accept that there is no such thing as "maintenance free" paint. You should practice yearly maintenance on both interior and exterior painted surfaces to prevent peeling paint and surface deterioration.
• Hand scrub painted surfaces with trisodium phosphate (TSP) and water. TSP is available at all paint and hardware stores in a synthetic version that will not harm groundwater. Add 1/8 cup of TSP powder to a five-gallon bucket of water. Rinse with clear water afterwards.
• Never pressure wash historic painted surfaces. Pressure washing does not scrape away old paint or clean the painted surface.
• Always store extra paint in a dry, warm area for touch up and maintenance.

The information presented here is not intended to provide comprehensive technical advice or instructions on solving historic preservation issues. Any information contained or referenced is meant to provide a basic understanding of historic preservation practices. Read full disclaimer.