Coppercoat Patina - effectiveness

[Tim Good]

I’ve just copper coated but the boat won’t be launched until next year.

Coppercoat say the boat should be burnished with 320 grit either from 72 hours after application or before launch. No difference.

But if I burnish it now to expose the copper and that copper then forms a green patina, would it be less effective.

Would it be best to sand it just prior to launch and leave the copper particulars suspended in the epoxy for now.

The worry is that after 6 months the expoxy will be rock hard and harder to sand / expose the copper.

Thoughts?

 

[KevinV]

I found the burnishing quite hard enough to do without leaving it months to harden further.

There's no way much copper is going to be lost in a few months of rain

 

[Tim Good]

I found the burnishing quite hard enough to do without leaving it months to harden further.

There's no way much copper is going to be lost in a few months of rain

I wasn’t suggesting the cooper would be lost, but it will oxidise with a green patina. Bare copper is more effective at killing bacteria that that which has a patina. At least it does in pans or water bottles

 

[Sandy]

Personally, I'd just launch when you are ready.

Never understood why Coppercoat suggests that you burnish the coating to start with.

 

[KevinV]

I wasn’t suggesting the cooper would be lost, but it will oxidise with a green patina. Bare copper is more effective at killing bacteria that that which has a patina. At least it does in pans or water bottles

I wouldn't know, but every coppercoated boat I've ever seen has a verdigris bottom - other than my own when freshly done

 

[KevinV]

Personally, I'd just launch when you are ready.

Never understood why Coppercoat suggests that you burnish the coating to start with.

Because every bit of the copper is covered with epoxy, you have to remove that thin layer to expose it

 

[Sandy]

Because every bit of the copper is covered with epoxy, you have to remove that thin layer to expose it

I have Coppercoat on my boat and it works well.

That is just not logical. Coppercoat is applied and forms an epoxy/copper matrix. How does the epoxy know that the last molecule needs to be at the juncture between the coating and the air? You then wave a bit of sandpaper over the matrix and somehow copper knows that it needs to be at the juncture between the coating and the air. After months at sea what happens? I hope some chemist or materials scientist can explain.

As for Coppercoat, mine just works. From time to time I park the boat against a wall, wait for low water then rub a thin layer of slime off. I'm not one of these skippers who launch, leave the hull to the vagaries of King Neptune then cusses their antifoul.

When I collected the boat after it was done she had been launched, it being Friday the crane team wanted to hit the bar and I can understand that, alas I did not get a good look at the hull before she was splashed. On running my hand over the hull before casting off I could not detect any evidence of sanding and on close inspection when the boat was out of the water still no evidence.

 

[vyv_cox]

Copper metal does not have good antifouling properties, it is the green copper oxychloride compound that does. I am guessing that this might not be formed if the exposure of the copper by burnishing was done months before launching.

 

[Tim Good]

Personally, I'd just launch when you are ready.

Never understood why Coppercoat suggests that you burnish the coating to start with.

I’m not debating the launch date.

The copper is coated in epoxy when you put it on. If you don’t burnish it then it doesn’t do anything. A few examples of that online and it literally does nothing without being exposed by sanding

 

[Tim Good]

Copper metal does not have good antifouling properties, it is the green copper oxychloride compound that does. I am guessing that this might not be formed if the exposure of the copper by burnishing was done months before launching.

Interesting! I knew I could count on you. Right ok so this complements the idea to sand/burnish now. If it oxidises over the coming 6 months then great.

Thanks. I kinda assumed the oxidised form didn’t work, but that actually doesn’t make sense as many owners don’t bother re sanding over their 10 year period.

I’ll crack on tomorrow as it’s now hardened after doing it last Tuesday.

Thanks

 

[srm]

Never burnished my Coppercoat and it worked and turned green sometime after launching. That is all except the areas where the supports had been and part of the rudder. I had kept one tin back to coat the support areas. It started to cure after I had rolled on about half the tin with waits between coats so slapped the rest on with a brush plus some on the rudder. I knew it was against the instructions but did not want to waste the materials. Six months later the brushed areas were still glossy brown and sported some growth. I rubbed them down a couple of times when dried out for pressure washing before they turned a uniform green with the rest of the hull. I assume that the thick brush application put too much resin on top of the copper.

 

[Sandy]

I’m not debating the launch date.

The copper is coated in epoxy when you put it on. If you don’t burnish it then it doesn’t do anything. A few examples of that online and it literally does nothing without being exposed by sanding

Even after reading the Coppercoat page I'm not convinced @Tim Good

Abrading Coppercoat. – Coppercoat Antifoul

Far to many 'wishy washy' words on that page for there to be any hard science behind what they say.

 

[Sandy]

Never burnished my Coppercoat and it worked and turned green sometime after launching.

That's interesting, it took over a year before my hull turned green and as there was just a layer of slime post COVID, when the boat had only moved 12 nm in well over a year, the Coppercoat was clearly working.

 

[Tim Good]

I wouldn't know, but every coppercoated boat I've ever seen has a verdigris bottom - other than my own when freshly done

As Vyv says then I might be wrong and that the green oxidised copper is in fact what stops growth, not the red new copper

 

[Tim Good]

Even after reading the Coppercoat page I'm not convinced @Tim Good

Abrading Coppercoat. – Coppercoat Antifoul

Far too many 'wishy washy' words on that page for there to be any hard science behind what they say.

That seems to be a little more about ongoing maintenance. The burnish I refer to is the initial activation which makes practical sense. Copper that is mixed with epoxy then it stands to reason that every particles has a little epoxy coating it.

 

[Daydream believer]

The reason you abrade the newly applied product is to expose as much of the copper particles as possible. When initially applied those particles are enclosed in epoxy so would have zero effect. The epoxy is an eroding epoxy & once in the water it is meant to slowly disappear thus exposing more copper particles. In theory a non abraded surface will eventually start to work but it will take a lot longer for the copper to be activated.
The reason one is advised to abrade every few seasons is that the epoxy may not have eroded fast enough & the copper particles will have disappeared from the surface. Abrading will expose the particles.
If one uses an abrasive that is too course it will put minute scratches in the surface. These microscopic scratches will attract fouling in the valley of the scratch. One needs a surface that is as flat as possible. I have found that the addition of lots of thinners during application does help in this respect.

 

[Tim Good]

The reason you abrade the newly applied product is to expose as much of the copper particles as possible. When initially applied those particles are enclosed in epoxy so would have zero effect. The epoxy is an eroding epoxy & once in the water it is meant to slowly disappear thus exposing more copper particles. In theory a non abraded surface will eventually start to work but it will take a lot longer for the copper to be activated.
The reason one is advised to abrade every few seasons is that the epoxy may not have eroded fast enough & the copper particles will have disappeared from the surface. Abrading will expose the particles.
If one uses an abrasive that is too course it will put minute scratches in the surface. These microscopic scratches will attract fouling in the valley of the scratch. One needs a surface that is as flat as possible. I have found that the addition of lots of thinners during application does help in this respect.

Good points.

On the issue of a flash surface, this is why I now regret sand blasting. I feel that with a little help we could have sanded back the surface and retaining more of the gel shield and on top, it would have been a smoother yet still abraded finish. The sand blastocyst process left peaks and troughs and pin holes. I should have removed the old antifoul by hand or with a chemical stripper.

 

[geem]

Personally, I'd just launch when you are ready.

Never understood why Coppercoat suggests that you burnish the coating to start with.

Because it works better. The suspended copper in the epoxy can all be isolated until you remove thr coating. When we first did coppercoat, it wasn't burnished. The first year performance was not great. We then burnished it and it performed far better.

 

[Sandy]

The reason you abrade the newly applied product is to expose as much of the copper particles as possible.

At the same time you might be abrading copper particles off the coating.

I asked in post #7 where are the chemists/materials scientist when you need one? They might have a better understanding of the reaction of the epoxy while curing.

 

[Daydream believer]

At the same time you might be abrading copper particles off the coating.

I asked in post #7 where are the chemists/materials scientist when you need one? They might have a better understanding of the reaction of the epoxy while curing.

But at the expense of exposing a greater amount of copper particles prior to launching. Thus improving performance.
What further understanding of the epoxy coating do you need, other than it is designed to slowly erode over its 10 year life cycle (or whatever) to expose further copper particles held in suspension?