Superior Stain?

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Arborcoat from Benjamin Moore comes in several flavors: transparent, semi-transparent, semi-solid and solid. This report from the field deals with Benjamin Moore product numbers 636 and 637, which are the transparent stain and clear coat.

Waterborne stains are not historically noted for their excellent performance on exterior wood. However, these two particular combinations are alkyd/waterbornes – a technology that several manufacturers have demonstrated to be potentially very effective in providing performance similar to, and in some ways better than, oil with a waterborne experience. We figured a big test for Arborcoat would be to see how it performed on exterior wood siding and decks, which can be a tall order.

“The 636 looks more like it put the color tone into the wood rather than leaving it on the surface.”


Last July, my company stripped a failed film-forming coating off a large log home in a harsh mountain exposure. The home featured a wraparound deck right across the front and part of two sides, as well as a large back deck. There were decks all the way around and logs above. After chemically stripping the failed coating from the home and decks, all wood surfaces were dustless sanded and refinished using factory-supplied Arborcoat 636 and 637.

There is no messing around when putting new product where previous product has failed. Our customers, our company and all good painters hold it to be self-evident that the new product will not fail with proper preparation and application.


637: The first step is the stain. The stain colors in this line are very rich. We checked out several during the color selection process with our customer, and our customer liked the cedar tone. In the can, it is a nice waterborne stain to work with; on the house, it is dynamite (a totally different experience than working with oil stain). The transparent stain feels thinner than other stains, spreads as fast as you can go, and penetrates deep and even. For a transparent stain, the depth and richness of color is surprising, and without that clay “pigment on the wood” experience of oil stains. It is a penetrator and looks more like it put the color tone into the wood rather than leaving it on the surface.

The “in-can” experience is pleasing. On a stir stick you don’t get the impression that there has been a lot of separation between the base and the color during its time on the shelf. Using good synthetic brushes, it holds and releases well with sufficient time to spread. Arborcoat dries quickly after application, unlike oil stains, which is great because exterior painters always have one eye on the sky in case of rain. I shudder to think how many gallons of oil stain I have spread in my life, but 637 was faster and cleaner with little to no blotchiness in both brushed and sprayed applications. No time or money spent on paint thinner and rags while exterior staining is a nice added benefit.

636: The clear is next. The 636 has a thin milky/watery consistency. If you use a brush that can hold it, you can fly with it, just keeping it moving and getting the surface wet. It has a very easy visual to follow. As you work your way across the side of the house, you can clearly see the modified 636 soft sheen take shape. It brushes and sprays well and hangs on without running. Unlike the clear films of the past, 636 is built to fade as it protects, and that is exactly what we have observed in its first-year performance on our test project. It has been a subtle fade, which is good.

In theory, a two-step stain coating process would take twice as much time as a one-coat oil application, but this was not entirely the case. The 637 stain coat goes faster than oil staining, and 636 goes on about twice as fast as 637.

If your crew is efficient and skilled, you can move quickly with these products. Sanding is discouraged and not required between the two steps. We experienced no grain raising on the stain step, and the clear flies over the top of it. The modified formulations are well-paired and the result is a low-luster, more like matte, sheen over the stain.

Together, it’s a fast and solid combo on well-prepped surfaces. The transparent stain penetrates quite deeply into the wood grain, which is still completely visible but with a pleasing and non-artificial-looking tone. And the clear coat pops it.

The job of the 636 is to protect the stain in the wood from failing. It becomes the maintenance coat going forward and is formulated not to peel but rather to fade as it weathers. Underneath it, the 637 has better color-retention characteristics than oil stains. The color doesn’t fade; the sheen of the 636 will. You can tell how it is doing simply by getting it wet with a hose and seeing how water beads up on it. If water doesn’t bead on it, it is time for some maintenance.

The 636 is the clear coat that services the entire line of Arborcoat stains (also available in semi-transparent, semi-solid and solid). It is the maintenance coat. That is what separates Arborcoat from the pack. Rather than putting on a stain and watching it deteriorate for five years, 636 is the maintenance indicator. If it fades out, you just reapply the clear coat without having to go through the prep and stain stages. The clear is pretty low-maintenance and easy to apply. The clear coat is only recommended to be applied on top of Arborcoat stains.


We have been watching our Arborcoat project carefully – just about monthly since last August when the job was completed. Our particular interest was in how the decks would do. The wood had snow and full sun all winter. That was really the test that would inform our experience with, and therefore opinion of, Arborcoat. It is the freeze/melt thing that is hard for wood but hopefully not Arborcoat to take. Constant expansion and contraction are where coating failures begin.

“nlike the clear films of the past, 636 is built to fade as it protects.”

The decks did surprisingly well, as did the entire wraparound rail system. The rail system had been sprayed with both coats during the project, and we found the viscosity of both to be ideally suited to spraying with HVLP and Graco ProShots; some of the footage can be viewed in the APC digital edition or on YouTube.

As advertised, the 636 clear faded some, but there were no indications of hard weathering, such as water staining. Being a waterborne vehicle, it also proved to be mildew-resistant, in sharp contrast to most straight oils. We will do a clear maintenance coat this year, and check the decks again in the fall.

The log siding on the house showed very little indication of any weathering at all – just a couple of minor spots that faded out to stain and less than a 5 percent showing for sure. We will do some clear feathering on those few spots. It is not necessary to do a full clear maintenance coat at this point, and Benjamin Moore discourages unnecessary application of the clear in maintenance coats. If you put a coat on a surface that does not need it, the surface will repel the new coat, as it should. Only put the 636 on in maintenance where it is badly faded or where stain is exposed.

Having seen exactly where previous coating on this house had failed and how bad, I knew the patterns to look for and was very impressed with the combination of the 636 and 637. I cannot speak with any authority on the other three Arbor-coat stain products, but the 637 looks excellent at its nearly one-year mark, the 636 did its job and the maintenance looks pretty easy. Many painting contractors are offering maintenance programs these days, and the Arborcoat system fits well with educating homeowners that finish maintenance is far less costly than subsequent failed surface restoration or replacement.

You may not have to strip a home like we did in order to use Arborcoat, but I do recommend, if you start integrating this new technology, that you work with your local rep to determine its compatibility with existing coatings and make proper product selections within the line. This is an important part of determining how to proceed in preparing surfaces for application. APC

Scott Burt is the president of Topcoat Finishes, Inc., in Jericho, Vt. He enjoys communicating with contractors and manufacturers at


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