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  1. #1
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    Jun 2012
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    Default Borate to keep algae off deck. Where can I get it?

    Hi,
    On an episode of ATOH, Tom helps a homeowner clean and stain a deck. After cleaning, and prior to staining, he recommends spraying a water/borate solution onto the deck to prevent algae from coming back. On the show it appears to be a thick viscous liquid (maybe a gel). I've called a bunch of hardware stores and also checked Home Depot and cant find this borate.

    Does anyone know where you can buy this liquid borate?

    Thanks in advance.
    Gregg

  2. #2
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    Default Re: Borate to keep algae off deck. Where can I get it?

    I did not see this episode, but TOH has used Sodium Borate solutions on a number of their projects. Two of the most common trade names are "Boracare" and "Timbor". Boracare is sold as a liquid that is diluted at either 2:1 or 50/50 with water, but it is not a gel. It is mostly ethylene glycol (antifreeze without the anticorrosive additives) and a Sodium borate.

    Timbor is a lot cheaper. It is a powder that can be mixed with antifreeze or with water. The antifreeze helps it penetrate into the wood better and it also will stops mold. mildew and algae. In fact it can be used without a sodium borate and sometimes is on wooden boats. The water or antifreeze must be heated up to get the powder to dissolve in it, boiling for water, 280F for antifreeze. Do this outdoors, especially if using antifreeze.

    Both the sodium borates and the antifreeze are water soluble so they must be protected by something that waterproofs the wood. You need a waterproofing outdoor stain, not just any stain.

    You can make your own sodium borate solution from common household products, Boric Acid and Borax. You mix a three cups of common laundry borax (20 Mule Team) with two cups of roach powder (99% boric acid) for each gallon of water or water antifreeze solution. The water:antifreeze solution can be 1:1 or 2:1. This would be the equivalent of the after dilution ratio of Boracare.

  3. #3
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    Default Re: Borate to keep algae off deck. Where can I get it?

    Quote Originally Posted by keith3267 View Post
    Both the sodium borates and the antifreeze are water soluble so they must be protected by something that waterproofs the wood. You need a waterproofing outdoor stain, not just any stain.

    You can make your own sodium borate solution from common household products, Boric Acid and Borax. You mix a three cups of common laundry borax (20 Mule Team) with two cups of roach powder (99% boric acid) for each gallon of water or water antifreeze solution. The water:antifreeze solution can be 1:1 or 2:1. This would be the equivalent of the after dilution ratio of Boracare.
    Thanks! This last solution sounds like the easiest to get all the ingredients for. Would the antifreeze still have to be boiled to get the Borax and roach powder to dissolve? Sounds nasty. I'm not sure if I can get my charcoal grill to get up to 280F

    As far as stain I was planning to go with a Cabot semi-solid decking stain. Funny, in this ATOH episode he doesn't mention what kind of stain to use but he does say to add 1/2 pint of spar varnish to each gallon of stain. I'm not sure if that Cabot stain is water proof.

    My deck faces north so it seems to be ripe for algae.
    Last edited by galbre; 06-25-2012 at 02:28 PM. Reason: update

  4. #4
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    Default Re: Borate to keep algae off deck. Where can I get it?

    I just got off the phone with a phone rep from Cabot. She claims their semi-solid decking stains are waterproof. However, she didnt recommend adding varnish to the stain as it will "turn into tar" in her words.

  5. #5
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    Default Re: Borate to keep algae off deck. Where can I get it?

    Yes, the antifreeze has to be heated to 280F. I use a cheap camping stove. Antifreeze is very toxic.

  6. #6
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    Default Re: Borate to keep algae off deck. Where can I get it?

    Think about the ground under the deck - you don't want to go polluting the soil. Anti freeze migrates well in soil and can kill lots of things.

  7. #7
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    Portland, Oregon, formerly of Chicago
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    Default Re: Borate to keep algae off deck. Where can I get it?

    I would second the warning about the toxicity of ethylene glycol. It is also sweet tasting, so keep your pets out of the area at least until it has dried. It will shut down their kidneys in short order.

    I would disagree with the Cabot's rep saying that their semi-transparent is water proof. It is water repellent, as are most transparent stains, but a certain amount of moisture will pass through it, especially as it ages. The water beading up does not last all that long. A deck stain has to be breatheable. It it does not breathe, it peels! To that extent, I would be reluctant to add varnish to their stains. At some point, the wood will no longer be able to breathe.

    Now and then I get a customer who says they want to varnish their deck. I caution that if they do so, it will look beautiful this year, and I will further guarantee that it will begin to peel next year. If you can't totally keep water out of wood (which you cannot on a typical deck), for goodness sake, don't put something on top of it that cannot let the moisture pass back on through it when the heat of the summer arrives!

  8. #8
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    Default Re: Borate to keep algae off deck. Where can I get it?

    Quote Originally Posted by HoustonRemodeler View Post
    Think about the ground under the deck - you don't want to go polluting the soil. Anti freeze migrates well in soil and can kill lots of things.
    Actually I would consider this a plus, I don't want things living under my deck. I would not be too concerned about this unless I had a well very close to the deck. But the sodium borate solution can be used with plain water if that is a concern. The Boracare which has been used on TOH does contain ethylene glycol.

  9. #9
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    Default Re: Borate to keep algae off deck. Where can I get it?

    ordjen is correct about using a water resistant stain. I should have used that term. The stain will lose its water resisting qualities after awhile and the sodium borates will leach out so it will be necessary to retreat and re-stain every so often, which is true no matter what type of preservation treatment you chose.

    I believe that the term "water proof" is often used in products, but it does not always mean moisture proof or vapor proof. Some "water proof" products claim that they will breath and pass water vapor.
    Last edited by keith3267; 06-27-2012 at 05:25 PM. Reason: add second paragraph

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