Copper Napthenate

[TroyC]

 


Need to replace a few top boards on bulkhead. I milled 16'  2x12 and 2x10 SYP. Dried, planed, coated with copper napthenate. They will also get a coat of natural water-repellent stain. They get restained every couple of years.

The old boards lasted about 10 years. Guess I didn't get what I paid for back then. They were supposed to be the really good pressure treated, I think they call them 3.5 or something.

I'm wondering how long should I expect my homemade boards to last in the elements?

With pressure treated prices, I'll gamble my time and materials. Just wondering how long I should expect them to last.

[Don P]

Are the old ones rotted or just ugly?
Paint a scrap, let it dry, then cut it in half, should give you some idea on penetration. The heaviest PT I've bought was 2.5 lbs per cubic foot retention for marine use, where most ground contact CCA was .60 and the box stores were selling .40 and .25.

[TroyC]

Couple of the top ones are pretty much  rotted thru. I guess the 2.5 is what they were supposed to be. The uprights for the retaining wall are fine. The cap boards are not holding up as well even though I reseal them every other year.

I did some 2x8x29" planks for the walkway last week. Soaked them in a 5 gallon bucket of copper napthenate about 10 minutes on each end. The penetration was impressive. Might not have gotten the very center but the ends were solid green at least 6-8" up.

[longtime lurker]

End grain penetration will be a lot higher than sawn faces methinks.

I did some posts with CuNap a couple years back, they got four or five coats of concentrate thinned with kerosene. So far so good above ground, in ground I don't know but I filled the holes with sump oil and let it soak in, and keep pouring waste oil around them as I got it so I'm assuming they'll outlast me.

[Don P]

I've forgotten which thread we were on the other day talking about fence post treatment. I was in the reading room with a very old copy of the wood handbook and saw mention of this paper on the tire tube process with zinc chloride, @mike_belben ;
Tire-tube method of fence-post treatment (ufl.edu)

[TroyC]

Interesting read on treating poles with tire tubes. The zinc chloride is sort of expensive.........