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Log siding presents much more of a sealing challenge than stacked logs for several reasons. As stacked logs season and shrink, they settle on top of each other. If there are sealed gaps between the logs, the width of the gaps between the logs may remain fairly uniform as the logs settle. On the other hand, log siding is nailed or screwed into dimensional lumber which holds the siding in place. As shrinkage occurs, the gaps between the courses can become wider and wider (see pictures below). In addition, if the siding is not properly attached to the wall, it can twist and warp, creating even larger gaps between the courses.


NBS-30 is an oil-based insecticide additive for paints and stains. Pure and simple, oils and water do not work together and we DO NOT approve the use of NBS-30 in any of our finishes.


Just as clear coats are vital to the performance of today’s automotive finishes, our Advance™ Topcoats are an integral part of all of our exterior finish systems. Not only do they extend the life of the color coats, but they do much more.

Hand sanding is a commonly used technique to prepare wood surfaces for a coat of finish. Sanding may be used after media blasting, pressure washing or to touch up areas that are needing maintenance or repair. One common mistake is to sand the surface as smooth as possible.

Mold and mildew (actually another name for mold) are colonies of living organisms that can grow on the surface of many materials including wood. Their color may range from white to black with just about every color in between. If the discoloration is green, it is most probably algae, a plant, since molds and mildews do not contain green chlorophyll. Like most living organisms, molds require air, water and a food source for survival. Bare wood is quite susceptible to mold growth since the porous surface provides lots of places for spores to germinate and many of wood's nutrients are available as food. This is especially true for newly harvested wood that still contains a high sugar content. In addition, bare wood absorbs water, thus supplying the moisture these organisms require.

Combating Different Molds

Although it is fairly easy to remove mold from bare wood surfaces (Wood ReNew does an excellent job), preventing its growth on green logs in particular can be somewhat of a challenge. Thanks to the internet, one popular misconception is that borate treatments will prevent the growth of surface molds on wood. This is NOT TRUE! Although the presence of borates will inhibit the growth of some types of surface molds, there are other types that actually thrive on borate treated wood. Borates are quite effective against wood decay fungi, but surface molds are very different from decay fungi and it takes other methods of control to prevent their growth.

Best Methods to Prevent Molds

When it comes to preventing the development of mold on wood, the best and most effective approach is to provide a dry environment. Molds cannot survive in dry conditions so if the logs are stored under cover with lots of air flow around them chances are that mold will not grow on them. But as we all know there are occasions when ideal storage conditions may not be practical so in those cases how can the formation of mold be prevented. There are some chemical treatments that can be applied to bare wood that will kill existing mold colonies and prevent the growth of mold for several months. One of the more commonly used products is didecyl dimethyl ammonium chloride, commonly referred to as DDAC. It works well and several years ago we used to sell a brand of it named Britewood XL. However, one downside of DDAC is that it is corrosive to skin.

Another chemical used for killing and preventing mold growth is chlorothalonil. At low concentrations it is commonly used for preventing fungal growth on peanuts and potatoes as well as being a fungicidal additive to paints and stains. Sostram Corporation makes a chlorothalonil product named CLORTRAM that inhibits surface mold and stain causing fungi growth. Neat chlorothalonil is very toxic to aquatic life.


Although there are several other products available for controlling mold, the last one we will cover is Mildew-X. Mildew-X is a dry film preservative that prevents mold and mildew growth on interior and exterior surfaces naturally. Mildew-X is exempt from FIFRA registration.

So, is there a role that a Perma-Chink Systems product can play to prevent the growth of mold on bare wood other than one of our complete finish systems? If a manufacturer or contractor wants to protect their logs at the mill or on the job site during construction, they can apply a coat of Prelude that has been dosed with Mildew-X or an equivalent product that is labeled for adding to water-based paints or stains. This will help prevent the growth of mold on top of the Prelude film. The limitation of this combination is that it must be applied to a fairly clean surface since it may not kill all of the mold colonies that are already present. However, it offers some definite advantages over those products that just eliminate and prevent mold. First, since Prelude contains UV Boost, it will help prevent surface graying due to sun exposure. Second, the Prelude film will keep the surface cleaner during transport and construction. And third, it will help regulate the drying process which to some degree should lessen initial checking and fissuring. We already have some manufacturers using this system and they are quite pleased with the results.

 Mold Growth on Bare Green Log

Although we have never identified exactly what it is, there is a magical ingredient in Perma-Chink that acts as a magnet to human fingers. Put an adult or juvenile male anywhere close to a wall with a fresh application of Perma-Chink, and the first thing that happens is one hand comes out of their pocket with one or more fingers magnetically attracted to the chink joint.

All of our stains and sealants are water-based, and while they are still wet, most clean up quite easily with just soap and water. That’s usually the best method to use for cleaning our wet, uncured products off of windows, gutters, downspouts, and other smooth surfaces, but there are occasions when other clean-up techniques should be used to remove some of our textured sealants from wood surfaces.

Do you need to remove any caulk that’s already in place before applying Energy Seal™, Woodsman™, or Check Mate 2®? Applying new sealant over old caulking is never a good idea, even if it looks like the old caulk is still sticking to the wood. The old caulk should be removed for several reasons.

Rips and Tears

repairingpermachink3Occasionally rips and tears form in log home chinking, especially in new homes that have been constructed with fairly green wood. Most of the time these tears appear on the top edge of the chink joint. That’s because during the tooling process, most people tend to pull product from the top to the bottom of the chink joint, which results in a thinner than recommended layer of chinking along the top edge. In addition, people forget to “push” the chinking up against the top edge, resulting in inadequate adhesion. When the logs shrink, it puts a strain on the chinking and if it was not properly applied, it can pull away from the wood. So when working Perma-Chink®, it is important to keep pushing the product towards the top of the joint.

Much of our technical literature and many of our articles refer to pH as it relates to its impact on bare wood and finished surfaces. Everyone should have a basic understanding of what pH means and how it is measured.

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