Removing failed Copper Coat

[Sawbonz]

We got a bad application of Copper Coat in the Caribbean. Starting immediately we had more barnacles than we could count and subsequent "burnishing" by two power sanders over two days did lots of damage including multiple spots down to the barrier coat and one to gel coat. A few months after that we lost our first piece of about a square foot, followed by more over the next year and a half. With so, so many problems it has become clear that the only solution will be to remove the Copper Coat entirely. This post is not about the product or the applicator, though another in the future may be, it is about the removal of the failed paint.


Remedy is in a yard in Mexico. One day after we arrived there my wife had a medical emergency requiring evacuation and it will likely be months until we can return. During that time the boat can be repainted after stripping. The yard typically uses sand but says that they can try a planer or import walnut shells if requested to do the job. Our Leopard representative doesn't like the idea of sand blasting on a fiberglass boat. I would like to solicit the opinions of those here who may have had to remove paint using the different methods and can point me in the direction of best results more than cheapest cost.

[kenbo]

It's easier to say what I wouldn't do. I would not use a planer or sandblast. It takes a bit more time but in the hands of an experienced person the safest method is random orbital sanding. I'd plan on renewing your bottom coat as well.

[rslifkin]

Orbital sanding will work. Blasting with a gentler media (walnut shells, soda, etc.) is common as well. Sand is too aggressive, but with a gentler media, a good blasting guy can nicely take the paint off down to the barrier or gelcoat without hurting the boat or ripping it down to bare fiberglass.

[kenbo]

Originally Posted by rslifkin

Orbital sanding will work. Blasting with a gentler media (walnut shells, soda, etc.) is common as well. Sand is too aggressive, but with a gentler media, a good blasting guy can nicely take the paint off down to the barrier or gelcoat without hurting the boat or ripping it down to bare fiberglass.

That's the point, coppercoat is pure epoxy with powdered copper in suspension. Soda blasting will not be effective and perhaps walnut shells might be but orbital sanding will be effective.

[GRIT]

I've had great luck with our Makita PV7001C, using an 8" pad and 36 grit paper, on low speed. It'll do the trick. With copper impregnated epoxy, you may have to try different grits. When you try to sand copper coated epoxy, sometimes the epoxy will warm up, and "grab" the paper, which then causes a gouge in the surface. You may have experienced this already, since you said you went through to the gelcoat in one place. If this is the case, use a heavier grit, and lighter pressure will often be the cure.

I've removed copper impregnated epoxy from a hull, and it's not easy, due to the above mentioned issue. Best method I've found was to be sure to keep the sander moving, and not sit in one spot for long. It's always tempting, when you see it start to do it's magic, to just get a little more off. The trick is to keep moving, basically doing a metre squared at a time, starting in one corner and working your way back and forth to the bottom corner, then starting over at the first corner. This way, the epoxy has time to cool before you hit it again. The speed at which you move the sander will be a learned thing. If someone else is doing it, don't get a brute. You'll need someone who's patient, and pays attention to what's happening under the sander.

If you're having flaking issues, try a scraper and see if that works.

I've no direct experience with blast media. It might be better than a sander, or not.

Good luck.
Paul.

[Clivevon]

What is Soda Blasting?
Soda blasting is a process much like sand blasting. The two can overlap in certain circumstances, but in general, they serve different purposes. The main difference lies in the material.

Soda blasting is a newer form of abrasive blasting that was invented in the 1980s and is milder than sand blasting. It uses sodium bicarbonate—otherwise known as baking soda—and, with equipment similar to that used in sand blasting, blasts the particles against a surface to clean it. While soda blasting can be used to smooth surfaces for coating preparation and remove rust, it is primarily used to clean.

Soda blasting is especially effective on surfaces like wood, chrome, and plastic. In other words, surfaces that are softer or require a gentler touch work well with this type of blasting, as it is less likely to damage the surface. Because of the low risk of distorting the surface, soda blasting is suitable for use on a wide variety of surfaces. It is especially practical in automotive restoration, cleaning wooden surfaces like decks and doors, and cleaning in masonry applications.

[Clivevon]

Sorry to hear about your issues with Coppercoat. I've had my boat done twice with a 12 year interval so it worked fine for me. Sounds like it was very much down to your installer.

Do you really need to remove all the coppercoat? Maybe you just need to remove all the stuff which will come off fairly easily (which might be all of it but might not)? I posted some info about soda blasting which I know is gentler than sand. You might also consider dry ice blasting - which is clean because it leaves no residue at all.

I could understand if your coppercoat was peeling off a cast iron keel because I know from personal experience that you have to put a very effective barrier coat (ceramic microballoons) onto cast iron before Coppercoat will stay on it. But it should stick to an epoxy barrier coat on GRP without problems.

Good luck anyway.

[Gaia]

I do not know if this is a help or not but here in the Rio Dulce I have seen antifouling paint removed from fibre glass boats by wet sand blasting and it appeared to do the job without damage. And further to the comment about CO2 blasting; yes no residue from the blasting material but of course plenty from the copper and epoxy. Might that be an environmental problem and could that be an argument for wet sand blasting? Or for orbital sanding with good vacuum assist?

Jim sv Gaia

[Martkimwat]

Originally Posted by kenbo

That's the point, coppercoat is pure epoxy with powdered copper in suspension. Soda blasting will not be effective and perhaps walnut shells might be but orbital sanding will be effective.

Not strictly true, as the 'epoxy' used by Coppercoat is a water based epoxy that is designed to slowly erode, thus allowing fresh copper particles to be exposed. I would suggest you contact Coppercoat direct and ask them since they will be the people who know their product the best. I have found them exceedingly helpful in the past, or at least here in UK. I have had three boats copper coated, the last two I did myself so am very familiar with its application.

When I did my last two boats , I got the bottom soft sand blasted as you need a certain degree of roughness to provide a key for the Coppercoat to adhere too.

[Sawbonz]

Hi All. Thank you for the replies and my apologies for not being back here sooner. I was waiting for notifications of new posts that never came. Totally my fault.


GRIT, to be clear, the applicator went through to the gel coat. Also, it isn't flaking issues, it's come off in sheets. That part is extremely easy to take care of, lol!



Cliveon, yes, it needs to go. There are several spots, approximately 6, where a sq foot each has already come off completely. There are several other areas that were sanded too far totaling another square foot or two and of the remainder there are multiple areas where I have been educated that the spots are indicative of wetness trapped in the paint. You could actually watch them dry out over the weeks that the boat has been on the hard. It is a complete mess and patchwork repairs would probably not last that long, especially when you consider how much of the remaining thickness was removed during those two days of sanding by the applicator.


kenbo, I am concerned that two guys for two days were only able to "burnish" to this extent and that removing it all would take weeks. I will be farming out this job to the yard where she lies now.

[Sawbonz]

I did just speak again with the Mexican yard manager who described the process that he is proposing in a little more detail. Basically, sand blast off 95% of the paint and barrier and orbital sand the rest. His employee has 40 years experience and varies the pressure and distance to avoid removing too much. Sounds good.


He also mentions that sand is a good desiccant when used like this and will help dry the hull. I didn't know that this is a thing, but it also makes sense.

[Sawbonz]

Originally Posted by Martkimwat

Not strictly true, as the 'epoxy' used by Coppercoat is a water based epoxy that is designed to slowly erode, thus allowing fresh copper particles to be exposed. I would suggest you contact Coppercoat direct and ask them since they will be the people who know their product the best. I have found them exceedingly helpful in the past, or at least here in UK. I have had three boats copper coated, the last two I did myself so am very familiar with its application.

When I did my last two boats , I got the bottom soft sand blasted as you need a certain degree of roughness to provide a key for the Coppercoat to adhere too.

I have been dealing with Coppercoat USA as they recommended not only the applicator but the current yard who will be doing the repairs/replacement. My assumption has been that they have instructed the yard on how to remove, but perhaps it is better that I clarify. Good point.



I have considered that contacting the UK headquarters may get a more pleasant response than I have had to date, but haven't made that effort yet.

[DefinitelyMe]

It sounds to me like the yard has a good solution, but if you're still looking for input:

I used to operate a wet sand blasting machine (called the Farrow System). We had three different grades of sand and could vary pressure, sand:water ratio and volume. We could blast thick rust from girders, prep a steel bridge for painting, remove road paint without marking the asphalt beneath or remove the paint from a soda can without damaging the metal beneath, or clean the gunk out of teak furniture without damaging the wood itself. It was an extremely versatile system and, in the right hands, perfect for what you are trying to do.

[Searles]

Try soy gel have had success removing anti foul and copper coat with this stuff plus eco friendly ,sofa blast is also v good plus walnut shell blasting on grp steel and timber bottoms ,.⚓️⛵️

[Boatguy30]

I would have them sand it with 40 grit and apply primicon or seahawk tie coat and then some bottom paint. Swine you are considering seahawk for that.
Currently in NZ and there is so much farm runoff in water these days that had to go to hospital for small bump on my knee that got infected and growth is worse here than in Caribbean.