17 Feb Know When Your Log Home or Cabin Needs Refinishing
All log homes will need some type of surface maintenance to provide protection from the elements and preserve the wood from harm.
To test your finish, use a spray bottle to mist the logs with water. If the water sheets off, leaving the stain color unchanged then it’s doing the job. If the logs soak up water, then it is time for another application of finish.
It is important to point out that even the best finish won’t properly adhere to a substrate surface that has been compromised. Similar to spray painting over rust on an automobile, if what is beneath the stain fails it will take the new finish along with it.
A simple test to determine the surface integrity is to observe the logs on the sunny side of your home (usually the south side). If you can scratch with your fingernail across the grain and wood fiber is removed, this is evidence that UV radiation from the sun has sacrificed the lignin (organic glue that holds wood fiber together) and the surface is in early stages of degradation. In this case, the existing stain and loose wood fiber must be removed prior to reapplication of a stain product. This is most often by chemical or dry media removal (addressed in detail elsewhere on our site).
How soon your home will require refinishing depends on many variables. Severity of weather exposure, care during preparation and stain application, as well as the quality of the stain used are primary factors. Homes in North America usually show finish failure first on the south and west sides (due to sun exposure and weather) and even the best oil-based finishes require application as often as every 2-3 years. Acrylic finish systems can be expected to last much longer.
The mechanics of a traditional oil finish require the sealant to perform an almost impossible task: remain on the surface offering protection from the elements, while it simultaneously soaking deeper into the wood. As professional applicators, we work with finishes from a variety of manufacturers. Until recently, oil-based finishes remained a cost-effective means of sealing and protecting your log home. But government regulations have changed that. Traditional oil finishes are rapidly disappearing from the log home landscape.
Oil finish manufacturers are being required to reduce volatile organic compounds (VOC’s) to meet federal EPA regulations. Many of these new finishes have been “watered down” to meet the restrictions and we find that the same finishes we applied in years past are no longer made with the same formulas. This has prompted the development of new (and better) finish technology. At best, oil finishes are becoming hybrid water-based oil blends wherein the oil molecule is split, making it smaller than the water molecule carrier agent. Once applied, the water evaporates, allowing the oil molecules to remain in the surface of the wood and regroup into complete oil molecules. This technology eliminates the primary environmental threat (VOC contained in mineral spirits, which have been blamed for ozone depletion) for those desiring an oil-based finish. However, oil is still a liquid and will continue be absorbed by the wood, which requires frequent reapplication (generally recommended by manufacturers each 3 to 5 years).
The current industry movement is in the development of water borne acrylic finishes. These finishes are environmentally friendly and dry to a water-repellant breathable finish which functions like Gore-Tex clothing. The finish allows moisture from the logs to exit while preventing the intrusion of water from the outside. Another feature of these finishes is that they remain flexible coatings that won’t chip and flake away from the logs. And because they are solids (optically transparent but chemically classified as a solid as opposed to a liquid) once dry they are not subject to further absorption, so reapplication of stain is seldom if ever required.
Acrylic finishes use a multi-step process to obtain the best results from each of the system components. The stain colorant is derived from transparent aluminum oxide pigment: tiny particles of colored aluminum flakes which provide the desired color pigment while blocking and reflecting the damaging UV rays of the sun. Darker stain colors may use iron oxide pigment which serves the same purpose.
Once the existing log surface is properly prepared typically two coats of stain are applied to the logs, each applied to the point of saturation. The first coat soaks into the wood, dries, and serves as a primer coat, serving to even out the absorption of subsequent coats. The second coat then saturates the wood outward towards the surface where further back brushing assures uniform coverage. These stain coats seal the wood and provide a beautiful transparent finish engineered to protect the wood from harmful UV damage.
The stain coats are followed by a clear acrylic topcoat which is very similar to the clear coat on your automobile. This topcoat seals and protects the logs and their stain finish, adding UV protection as well. Available in either gloss or satin sheen, this coating encapsulates your log home within a layer of breathable, acrylic protection. For those with carpenter bee issues, we’ve also had great success with adding a contact insecticide to this topcoat: carpenter bees generally don’t like to even try to drill into it.
Long-term upkeep of acrylic finishes is greatly simplified as compared to the old oil-based finishes. If the clear acrylic topcoat is maintained, the stained wood surfaces never make contact with the elements. In the worst-case situations (high sun exposure, south facing walls) the clear topcoat can be expected to last 5-7 years or more before any re-coating, and typically we don’t see noticeable wear for 8-12 years or more. In our experience, areas protected from direct UV radiation like porches, and shaded areas of the home rarely if ever require additional topcoat application. Perhaps the best feature of this process is that reapplication can be easily accomplished by the homeowner, if desired. The clear topcoat is easy to work with and is applied over the existing finish. With annual washing and simple spot maintenance of the topcoat, it is expected that the existing finish may never need removal or stain application.