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Thread: Black Spots in Western Red Cedar

  1. #1

    Black Spots in Western Red Cedar


    I was doing a deck for a client and we decided to experiment with a section of siding to see what's hiding under the weathering.

    One pass with the recommended ratio of 12.5% pool shock/water/Elemonator applied via X-Jet followed by a downstreamed pass of F-8 mixed to the recommended ratio.

    As you can see, parts cleaned up beautifully, but there are still those black splotches. Are those there to stay or is there a way to remove them?

    Also, if I can prove that the old clapboard can wash down well, there may be an entire house wash and stain job in it for me. Any strong thoughts on products to protect but still see some wood grain? I've used SW Woodscapes on old cedar shakes with success, but some of these old clapboards are cupping considerably. Might they want an oil instead? Thoughts on this front?

    Thanks all!



  2. #2
    Probably just tannins in the wood. I love it. I think it will stain beautifully with an oil. Armstrong Clark for a clearer look (transoxide pigment) or Bakers for a slightly more opaque look (clay pigments) but still shows and accentuates the grain. The latter may be better if you are going for a uniform look. This is a custom blend A/C on a cedar deck with wood similar to yours.
    Attached Images Attached Images

  3. #3
    Thanks Ken!

    With those finishes you mentioned, what would be your general expectations regarding future maintenance? How many years might we expect on the harshest exposures like high sun near a roof line? Also, would this eventually fail like a film like Sikkens and require a full strip?

  4. #4
    Oils are very easy to maintain. Since its mostly vertical, you will get 4-5 years before you get any significant fading. Maintenance is easy. Light bleach wash and and recoat. There is no build up like a film former. Super easy to strip too, should that need ever arise.

  5. #5
    Thanks again Ken. First off, I want to say I respect your opinion in this realm, it's clear you have far more experience than me. However, I'd be curious to hear some clarification if you don't mind. That maintenance schedule sounds ideal, but the problem is I've heard it before and been severely disappointed. First with Penofin, then with SW Superdeck Oil, and also with TWP. These are all non film forming oils that look great at first, and then after one year are discolored and sometimes growing mildew. To be fair, all of those experiences were on decks which are more challenging to maintain, but it still makes me hesitant to apply a similar product on a vertical.

    What's different about AC and Bakers that gives them 4-5 years?



  6. #6
    The big difference, Noah is vertical vs horizontal. No foot traffic, accumulated rain, snow and sun rays aren't beating directly down. Decks last two years, If it helps, I pass a cedar house we stripped and stained in 2008. It has not been touched since and still looks good. Keep in mind, not all oils are alike. There are long and short chain oils that cure differently. Mold is a tough one to predict. In shady areas on a north face you may get some growth. On a house, I add more fungicide to the mix so all that can accumulate is surface mold. If you can get the TWP100 series, thats a great alternative as well.

  7. #7
    Roger all that, thanks again Ken!


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