Copper Naphthenate 17% (2% as Metal) Double Strength - Highest Concentration Allowed - 1 Gallon - Wood Preservative

So far so good. Other reviews indicate the odor which is normal for a product such as wood preservative. It took me an hour to apply one gallon on 99 posts of either 5-inch or 6-inch diameter using a 2 1/2 inch brush. I was sloppy in application as the wood posts were installed 2 years ago and am just now getting to preserving them. Second coat will be applied in next few days but appearances are it is ready for second coat now. Recommend nitrile gloves. With outdoor application ventilation was vert good and odor disappeared rapidly.

Purchased and used a gallon to provide secondary preventive protection to (a) a new house's 6x6 pressured treated household power pole, (b) the pressured treated plywood backer for the power box, and (c) 168 linear feet of 5/4x6x8' ground contact pressure treated deck boards (ground placement, to help stop unwanted water & dirt erosion). Product is easy to use (I used a 3" foam roller), covering all end cuts and all sides of the lumber (including the deck boards' edges). It does have a distinct odor, though, despite the plastic bottle, ziploc bag, and Amazon box (like another commenter described). The odor lessens over time (for me, it was 3 months of waiting between order and use), and I could barely smell it during application. It soaks into wood well, even "big box store, too wet, lumber". However, for those that care about looks... you are applying a copper based protection to the lumber; It will be greener. Prevention of future decay, for my uses, was the goal. We'll see how it does many years from now... when this review likely won't matter. :)

No one can give an honest review of this unless they’re coming back 10 years after using it to mention if it works or not. I’ve used the Rustoleum version of this in the past so I was aware of the odor and thought people commenting on the odor were being over dramatic, after all, you’re buying it to protect wood, not freshen the air. I’ll say this, if the smell is any indication of how well it works it must work great. I’m surprised the post office delivered it… It was in a sealed plastic container, that was sealed in a ziplock bag, which was sealed in a cardboard box which was sealed in the Amazon shipping box and when I brought the package in and sat it on the table, before even opening the outermost box, the smell was filling the house and I had to sit the box outside. I used this to treat the entire top of a 10X20 deck we built for a hot tub, I went with this over the Rustoleum version because there’s was only .88 gallons (weird) this was a full gallon. There is also a higher percentage of the active ingredient in this, so you get more product and it’s stronger. It also smells a lot stronger than the Rustoleum so I’ll take that as it’s going to work better. I’ve seen people use the specialty deck sealers and stains and it just doesn’t last or hold up. None of those are code approved for treating structural wood that can then be buried underground so I figure this will work much better, I also wanted to keep the raw treated lumber look and this fit that bill, time will tell how well it works, so 10 years from now I’ll come back and update. The package says the smell and color will fade in time, hopefully the smell fades sooner than later because after treating the deck I can still smell it outside, strong, a quarter mile away walking up to my mailbox and the smell has permeated inside the house. Another plus, application was easy, I just poured it in a paint pan and brushed it on with a 9” brush, it soaks right in, no need to worry about brush strokes or marks. It also covers the area it claims, most things claim to cover so many feet and I end up getting about half what they claim. This says 100-300 sq feet and I got a generous 200 sq feet out of the gallon, with enough left over to 2nd coat heavy traffic areas. My only real complaints: There’s nothing on the label to indicate a before use cure time, it just says 1 hour before a 2nd coat if desired. There’s nothing on the label to indicate how long you have before rain. There’s nothing on the label to tell you optimal application temperatures. So I’m taking all that to mean none of it matters? There’s also nothing on the label to indicate if it gives UV protection or not.

Rated at four stars ONLY because it will take quite some time before its effectiveness can be judged. Product was very well.sealed; extra under the cap, heavy zip lock bag and two boxes. Speedy delivery. The smell is noticeable and will never be confused with Old Spice but it isn't heavy or pungent. Consistency is thin and goes on well with a lightly loaded trim roller. As I wanted it to penetrate, I was rather liberal with it. Where it ran, I let it sit for a while then rolled over it again. Goes on medium leaf green and lightens somewhat as it dries. It dries quickly to the touch (splotchy ) as to "cure" time (if any), I can't say and I can't advise if it's paintable. I intend the the finished project to be essentially out of sight so its splotchy appearance is no concern. The stuff IS pricy but I'll have no complaints if it doesn't rot and the bugs keep away. Addendum: After a couple days of drying, the green color is greatly faded but will never have the look of a proper stain.

This stuff soaks in good. I char untreated wood with a flamethrower then put this stuff on. The people saying it stinks makes me laugh. I’m a mechanic. This stuff smells like the inside a band-aid tin from the 90’s. Thats it. Just a really strong band aid odor.

I have used this product for over 7 years now, since approx. 2018. The stores I originally purchased it from no longer stock this, but AMAZON does. I have a 5" deep polyethylene flat dip tank, for treating "flatwork". 5 years ago, I dipped two 2'x4'x3/4" plywood pieces for 2 days, to cover outdoor generator sets during rains. Today, those sheets still repel rain as if they were waxed. Zero deterioration. I also have a 6" diameter x 10' long schedule 80 PVC "dip tube", set on an inclined angle of approx. 30 degrees. I routinely treat big box store treated wood for additional protection. I dip a 2x4x8' or a 2x6x8' , immersed in the tube for 2 days. A 2x6x8' absorbs approx. 1/2 gallon of the CuNap over 2 days. The ends of the board absorbs the treatment for at least 24" into the board, as evidenced by cutting the board. I have also done this for 5 years, and can say that absolutely nothing deteriorates the wood having this treatment, even if direct buried, of if constantly wet. This wood is used for scenic elevated boardwalks through a swamp. For 2x4 fencing runners, dip them for 2 days, let them dry for 2 to 3 weeks, then use an outdoor primer to cover the treatment color (if desired), and finish coats, OR, leave them plain with the greenish color au natural. Dip the 4x4 fence posts also. I have also "painted" the CuNap onto exposed fascia boards, and others needing protection from moisture, which will eventually mildew boards and turn them black from mold. One brushing of CuNap on the new board completely prevents that from happening. This product gets a 100% FABULOUS YES from me!

Great stuff! Wear your PPE though, stains whatever it touches. Easy application, dries quickly, good penetration, nothing bad to say.

I’m sure it will do the job it’s intended to. It came quickly and cap was taped down, gallon container was enclosed in a ziplock bag which was also taped and was also double boxed. There was no liquid leakage or any signs of such and container seems full, but outer box sealing tape was mostly broken and there was an odor of the product coming from both boxes. I believe this was only from vapor of this volatile stuff slowly making its way through the plastic bottle and the ziplock. I would suggest using a bag which is more impermeable to product vapor, padding between the two boxes which is more effective than the usual wisp of paper that’s normally used, and secure taping of outer box which will ensure its survival as a heavy item subject to rough handling. Came very quickly and otherwise survived its journey in good condition. Good price. Thanks!