I'm planning to use Bora-care as a preventive measure on some exterior wood. But I don't understand how to calculate the amount of water and concentrate to use. Here is the label with instructions: https://nisuscorp.com/download/bora-care?wpdmdl=1389&refresh=5f9496ee86a861603573486. For this first project, I have 500 cu. inches of wood (about 5x100x1) and I'd like to use a 5:1 ratio. So how much concentrate should I mix with how much water for that volume of wood?

I know I can mix 5oz of water with 1oz of concentrate or 6oz total, but is that enough to treat 500 cu. inches of wood? What if I want to use the same 5:1 ratio for 1000 cu. in. of wood? or 10,000?

  • it tells you on the label how to mix 5:1 ratio .... if you didn't read that, then what else did you not read?
    – jsotola
    Oct 25, 2020 at 6:14
  • you can just mix more if needed, using smaller "scoops"
    – dandavis
    Oct 25, 2020 at 20:51

2 Answers 2


Your area calculation makes it seem like you are treating a single 8' long 1x6 board. Anyhoo, the amount you need depends on the porosity of the wood. The instructions say to apply "to the point of saturation". If your area calculations are correct, than you probably need less than 1 gal. of solution. So, at an approximate 5:1, you need about 105 oz. of water and 21 oz. of concentrate to make a tad bit less than a gal. of solution at 5:1.

P.S.- math is not my forte

P.S.S.- I don't think you need perfect accuracy here...


OK, finally figured it out.

One gallon of Bora-care solution (128 oz of the water/concentrate mix) treats about 400 board feet. So that means 128oz/400ft = .32 oz of DILUTED Bora-care per foot.

So the formula to determine how much concentrate you need for a given amount of wood is:

(ft * .32) / (numerator of dilution ratio) + 1 = fluid ounces of concentrate needed

For example:

For 1:1 ratio, oz. of concentrate = (ft * .32) / 2
For 2:1 ratio: oz. of concentrate = (ft * .32) / 3
For 5:1 ratio: oz. of concentrate = (ft * .32) / 6

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