The ‘Madison formula’ was developed at the Forest Products Laboratory around 1950 as a simple linseed-oil-based finish that could be made from readily available components. It was one of the first formulations of its type – a penetrating finish that eliminated the problems with cracking and peeling commonly found with the oil-based paints available at the time. The finish could be made with pigment to give a semitransparent stain or without pigment to give a water repellent preservative.

Commercial oil-based semitransparent stains are available in a wide range of formulations, all of which must comply with EPA rules that restrict the amount of solvents or volatile organic compounds (VOCs). The stains are formulated with or without a registered pesticide (fungicide). If the stain contains a fungicide, it is usually labelled as a “preservative.” Many modern commercial finishes are better than the Madison formula, particularly those that are formulated with modified linseed oil. The finish should have the following attributes.

• Be oil-based
• Contain about 10% to 20% alkyd or similar resin
• Contain an inorganic pigment
• Be solvent-based
• Contain a fungicide
• Include 1% to 2% wax or a similar water repellent.

For more on Alternatives to the ‘Madison formula’, including information on other stains, water-repellent preservatives, and a formulation for a simple homemade water repellent finish, just follow the link!

This newly revised FinishLine covers the care of wood decks, including a review of penetrating finishes including Water Repellents and Water-Repellent Preservatives, Colored Water-Repellent Preservatives, and Semitransparent Stains.

Wood decks have become an important part of residential construction, adding versatile living space to a home and, with minimal maintenance, providing decades of use. Wood decks are exposed to high levels of stress, however, from severe weather conditions that shrink and swell the wood. Without proper maintenance, wood decks can develop problems such as checks and cracks, raised grain, and mildew, thus increasing the risk of decay and insect attack.

Because of these risks, lumber used in decks is usually pressure treated with a preservative, or the lumber used is a naturally durable wood such as redwood or western redcedar. Applying an additional finish to wood decks will minimize the problems of cracking, raised grain, and mildew growth.

A penetrating finish applied to wood decks provides better overall performance and is easier to reapply than a film-forming finish (e.g., paint, solid-color stain). In addition to the continuous shrinking and swelling of the wood caused by changes in the moisture content, film-forming finishes are subjected to excessive wear, especially in high-traffic areas. For these reasons, penetrating finishes, not film-forming finishes, should be used on wood decks.

House paint can “fail” for several reasons. This newly revised FinishLine reviews the most common causes, including:

• Wood was wet when it was painted
• Unfinished siding was exposed to several weeks of sunlight before painting
• Temperature was too cold when the wood was painted
• Wood was too hot when it was painted or was heated soon after painting
• Weather was too humid when the surface was painted
• Humidity in the house was too high during the heating season
• Wood was installed directly over foam or foil-faced insulation board
• House has no interior vapor barrier
• Wood siding was dirty
• Wood has mill glaze
• Wood has decayed (rotted)

The following tips can help prevent house paint failure (not applicable
to semitransparent or solid-color stains):

• Sand or power wash the surface of the wood if it is smooth.
• Apply paint during recommended weather conditions and temperatures.
• Treat the surface of the wood with a paintable water-repellent preservative (especially the end grain).
• Prime the surface of the wood with a stain-blocking primer.
• Install siding properly.
• Properly apply caulking material
• Apply two latex topcoats over the primer.

In the baker’s dozen of revised FinishLine publications, you will find no mention of specific commercial products. Although FPL wood experts such as Mark Knaebe can recommend specific techniques or methods for working with wood; FPL employees must refrain from recommending one product over another.

Happy painting!

The durability and beauty of wood make it an attractive material for bowls, butcher blocks, and other items used to serve or prepare food. This recently revised FinishLine covers finishes for wood bowls and items commonly used in food service or preparation such as butcher blocks.

This FinishLine explains how water-repellent finishes can reduce the effects of moisture and can make wood items easier to clean. Finished wood countertops, for example, are less likely to show stains. Applying melted paraffin wax is one simple way to finish wood kitchen items.

Two types of finishes are addressed: film-forming and penetrating. Finishes that form a film on wood, such as varnish, lacquer, and shellac, are also called coating finishes. Although the film protects the wood, it eventually chips, peels, or cracks. Penetrating finishes come in two types: drying oils and non-drying oils.

Information on this and other revised FinishLines is available through FPL’s website.