"Seal Once with a semi-transparent tint works well for rain screen hardwood siding. See more about the pros and cons we have learned here."
For many years we have tested, and continue to test, numerous sealers for exterior hardwoods. We have found there is no “perfect” sealer for high density hardwoods. The natural characteristics and properties that make these long-lasting hardwoods so durable, also prohibit deep penetration of stains and sealers. The tighter the wood cellular structural, the longer high density hardwoods last outdoors, but they are almost impervious to most stains and sealers.
Initial UV Protection is Critical for Best Performance
Having UV protection on the surface of rain screen hardwood siding is a critical success factor to the short-term acclimation of the hardwood on site – and the long-term performance of the wood as well. With Seal Once, it is the semi-transparent tints that provide the UV protection. Because of the low porosity of high density hardwoods, these tints are basically topical – they tend to lay on the outer surface of the wood. They do not penetrate deeply into the high-density surface of durable exterior hardwoods.
We have found Seal Once with semi-transparent tint to be an effective rain screen hardwood siding finish. Vertical surfaces are not subjected to as many environmental and weather conditions as decking (and there is no foot traffic on siding).The western exposure and southern exposure receive the most severe UV punishment on siding. The colors that performed best in our testing were the Bronze Cedar and Cape Cod Gray semi-transparent tints. We have found that the first coats hold up much better than any other products we have tested thus far. Seal Once tinted formulas have a low-luster matte finish.
Cape Cod Gray Semi-Transparent Tint for Hardwood Siding
The Cape Cod Gray semi-transparent tint has been widely accepted in the design community for hardwood siding for three important reasons:
The silvery gray color immediately helps create the appearance of the gracefully aged look of exterior hardwood siding
The tint provides UV protection for the exterior hardwoods during the critical initial acclimation period.
Transitions to naturally weathered patina over time
We have also found that as the gray tints fade off with natural weathering, and the actual surface of the underlying wood is slowly revealed, the wood weathers naturally and eventually replaces the initial 'silvery patina look' with an actual silvery-gray patina. In our experience, we have found there is no need to continually recoat the Cape Cod Gray tint as it fades, because the tint was designed to emulate the naturally weathered silvery-gray appearance that the hardwoods will ultimately achieve.
Bronze Cedar Semi-Transparent Tint for Hardwood Siding
The Bronze Cedar semi-transparent tint brings out the brown tones in most hardwood siding and helps to ‘even out’ and blend the natural color and grain variations for a more uniform appearance. As the elements attack and fade out the initial tint, the surface may be recoated at any time desired. We have found that the seasoned wood is much more receptive to the tints when re-coating the siding after the initial coat has weathered and faded.
If natural weathering is not the desired eventual outcome for a rain screen siding project, Seal Once tinted products may be used to recoat at any time that is desired by the owner. Hardwood siding that has been exposed to the exterior elements can be re-coated effectively with one additional coat and seems to hold more of the tint for a longer time.