What’s the best log home stain & log sealer?
Log cabins are beautiful, but if you don’t choose the right log home stain or log sealer, you can end up in a log home maintenance nightmare. Some of the unique characteristics of wood make it suitable for a variety of applications in the building industry: log homes, decks, rough-sawn siding, fences, and shingles. Without protection from sun and moisture, wood will weather and eventually deteriorate. A log home stain or log sealer is used to enhance the appearance of log cabins. They also add dimensional stability and prevent deterioration.
The weathering of wooden logs is a combination of chemical, mechanical, biological, and sunlight-induced processes that change the appearance and structure of wooden surfaces. After two months of exposure, all untreated logs turn yellowish or brownish, and then gray. Dark woods will become lighter; light woods eventually darken. Surface checks, raised grain, cupping, and warping all will develop as wood weathers.
Log Home Stain Types
Research conducted by the Forest Products Laboratory indicates that failure to properly treat new lumber can reduce the average life of wood by 20%. Understanding the differences between different types of log home stains makes it easier to select the right product. In the past, stains were made from alkyd or natural oil resins, such as linseed, tung, soya, and paraffin. The resins were often blended with waxes to provide additional water repellency, and then diluted with a mineral spirits solvent.
Technological advances and environmental regulations on emission levels of volatile organic compounds (VOC’s) have sparked the development of new products. Water-based products, particularly those formulated with certain water-reducible synthetic oils and resins, have excellent penetration and perform as well as, or better than, oil-based (alkyd) finishes. The American Society for Testing and Materials (ASTM) has standardized test methods to measure the water repellency and color retention of wood finishes. In ASTM test D5401-93, a finish is applied to a 2″ by 4″ section of wood, allowed to cure for seven days under controlled conditions, and then tested for water absorbency.
Standard ASTM G53-88 evaluates the water repellency of coatings exposed to ultraviolet light and condensation in a weather exposure chamber for 1000 hours. Manufacturers also use outdoor testing to measure weathering in different climates, and they might provide test results if you request them. Finishes are generally classified into two basic categories:
- Film Forming Stains – Those that form a film or surface coating on wood
- Penetrating Stains – Those that penetrate into the pores of the wood.
Film Forming Log Sealers
These products form a film or coating, that creates a barrier between the wood and the elements. Film-formers include many alkyds, latex/acrylics, and varnish resins in solvent or water-based finishes. Products without pigments are considered to be a clear or transparent finish, and have little or no protection from ultraviolet (UV) radiation. Pigments are added to paints, solid color stains, and semi-transparent finishes to change the appearance of the wood and to provide protection from UV rays.
Some of the newer water-based coatings are semi-transparent acrylic blends that have excellent flexibility. Unfortunately, due to their higher molecular weight, some acrylics still form a film on the surface of wood, and are subject to the cracking that is a characteristic of all film-forming finishes. Film finishes crack as wood expands and contracts during normal moisture cycling and water gets underneath the finish and deteriorates the wood. Removing film-forming wood stains can be difficult, but is often necessary before re-application. If the failing coat is not removed, then the new coat may blister and peel. For these reasons, film-forming finishes are generally not used on log homes.
Penetrating Log Home Stain
Log cabin stained with DEFY Wood Stain
The best exterior stain for log homes are oil or water-based products that saturate wood pores to prevent water penetration. They typically contain a drying oil or resin in a transparent or semitransparent stain. Advantages of penetrating stains over films are that they provide long-term water repellency, they don’t trap moisture in the wood, and they do not peel or blister. Natural oils (linseed and tung, for example) are initially very effective in stopping the absorption of water into wood, but tend to darken over time because they are a food for fungi. Buildings treated with natural oils and resins generally need extensive cleaning before reapplying the finish.
Some of the newer water-based systems are made with synthetic resins with added zinc to deter mildew growth and they provide excellent water repellency and color retention. One of the main advantages of synthetic resins is that unlike natural oils, they do not serve as a food for most biological growth, making future coats easier to apply. Penetrating finishes are ideal for use as a log sealer as they are easy to apply, easy to maintain, and won’t peel. Semi-transparent log home stains are by far the most popular finishes for the log home market.
How Do You Stain a Log Home?
Correct application technique is critical to performance. Follow the manufacturers’ instructions, particularly with the newer water-based formulations. All finishes should be applied to a clean surface, but penetrating finishes must be applied to surfaces that are porous and free from previous coatings. Although chlorine bleach will effectively remove many stains like mold and mildew, it can damage wood and is toxic to people and plant life. An oxygen bleach deck cleaner is environmentally safe and can actually increase product penetration up to 25%.
Wood that is pre-treated with a cleaner or power washer will probably have some have better finish penetration. Water-based finishes tend to dry faster than oil-based products. To avoid lap marks, particularly on hot sunny days, apply these only in the shade: the cooler surface will absorb better and allow for easier application of a second coat.
How Often Should a Log Home Be Stained?
Routine maintenance is necessary, but the life-span of a sealer or log stain depends on a variety of factors including:
- Construction details
- Exposure to mother nature
- Product choice
- Surface preparation
- Application techniques
All of these factors are essential to success. Some finishes may even require chemical stripping or sandblasting to restore wood to the proper condition before re-treatment. Finishes that weather unevenly and are re-coated without removing the old finish will have an unsightly, patchy appearance.
Although the log stain is only a small percent of the cost of a log home, it is one of the more critical elements in construction. To most consumers, aesthetic appeal is just as important as performance when selecting a wood finish. Understanding the properties and expected performance of various products makes the decision process much easier for you.
One of the better products on the market that’s geared specifically toward log homes is DEFY Extreme Semi-Transparent Wood Stain. It’s been a go-to stain for log cabins for decades and has a great track record of performance. Before staining, make sure to properly prep your wood first.