can a unopened can of anti fouling paint last 10 years

[roverhi]

Had a left over can of Interlux Micron bottom paint left over from a bottom job. Paint had been opened and a quarter of it used. Used it after 6 years in storage ashore and performed as it did when new. Stirred it with a pretty hefty stick to get the solids off the bottom. Took a bit of stirring but mixed up well with a little more work than a fresh can. Don't see a reason that a sealed can wouldn't last 10 years.

[Scout 30]

I sure hope it's not a problem because I've got 3 cans of Trinidad that are over 5 years old.

[powsmias]

Originally Posted by Jon Hacking

Manny, I don't know, but I wouldn't try.

When we crossed the Atlantic from Cape Town in '81, a 1 year old can of antifouling rusted through and leaked into the bilge. We didn't notice at first, but we did notice that Margi didn't come up for her watch. No problem, she was asleep and there were lots of folks on deck so we stood her watch for her. But then we smelled the paint fumes and realized that we couldn't wake her up. So we carried her up on deck for some fresh air and looked after her as best we could. She eventually woke up about 24 hours later, and seemed fine. But a few years later she developed brain cancer and died, while still in her 20s. I don't know if the events are related, but we now don't carry many old paint cans...

So very sorry to hear of your loss sir, all the best..

[jmschmidt]

The poor guy didn't say anything about keeping a can of bottom paint in his bilge. That's industrial strength stupid. It was a general question about the shelf-life of bottom paint and several responders went off on a bilge storage tangent. If fact keeping bottom paint anywhere on a boat is a dumb idea.

Yes, bottom paint will keep indefinitely. Store it in plastic zip bags or other air-tight sealable wrapping and turning it over once in a while is a good idea. Check frequently for leaks and place the container over a drip pan but don't ever put anything in a metal container in your bilge. If fact don't store anything in the bilge period.

[wrwakefield]

This spring I used 3- 1 gallon cans of Petit Hydrocoat bottom paint that I had stored for 3+ years. [And never inverted...]

Those cans were made of plastic, so there was no risk of corrosion. [Hydrocoat is water based...]

As advised by the manufacturer, to mix I decanted about 1/3rd of a newly opened can into another container. Then I mixed the copper into the remaining contents in the original 1 gallon can using a drillmotor driven paint stirring paddle.

It was well mixed within about 5 minutes. I then poured the remaining 1/3 back into the original can and finished mixing it all in a minute or two. Once mixed up I poured that into a 5 gallon bucket [leaving no copper or paint behind in the original 1 gallon paint can.

I left the stirring paddle with drill attached in the 5 gallon bucket so I could stir it up a bit every few minutes as I rolled a coat onto the boat.

This approach worked very well, and I could discern no issues with the paint despite my having warehoused it for 3 years.

In case this is useful.

Cheers! Bill

[BlackHeron]

Originally Posted by jmschmidt

The poor guy didn't say anything about keeping a can of bottom paint in his bilge. That's industrial strength stupid. It was a general question about the shelf-life of bottom paint and several responders went off on a bilge storage tangent. If fact keeping bottom paint anywhere on a boat is a dumb idea.

It could be for a lot of folks here who live aboard full time the idea of storing anything off of the boat just wasn't considered as even an option.

[Compass790]

Originally Posted by Mannyslv

i was debating with a friend of mine weather or not a can of antifouling paint can last 10 years if it has never been open.

if you flip the can every 3 months lets say, will that help the copper not get stuck together.

would apreciate any comments about this subject
thanks

We used some that was much older than 10 years, took forever to mix up & never did properly actually. Was a bit grainy but worked much better than modern paints. Suspect it may have dated from TBT era but don't know.

[Chuck Hawley]

My vote is that the paint in the can last 10 years. I have two precautions:

1. Obviously the can has to be 100% sealed so the volatile components don't evaporate.

2. The solids could possibly settle into a layer that could not be put back into suspension. This is hard with a can of copper-based paint that's six months old, and I presume it would get harder and harder. Turning the can on a regular basis might have some beneficial effect.

I doubt that the motion of the boat would have any effect on keeping the components mixed. Once it separates, I think only an electric mixer would have much beneficial effect.

Chuck

[Jim Cate]

Turning the can on a regular basis might have some beneficial effect.

Chuck, I suspect that to be useful, the inversions would have to be pretty frequent. Once the solids have settled into a bottom layer they are pretty firm... as evidenced by the resistance to stirring that we've all encountered in a newish tin, just off the shelf at West marine!

But, a power stirrer will resuspend it pretty quickly and evenly IF the volitiles are intact.

Jim

[AlanR]

Inverting the cans frequently (not regularly; Halley's comet is regular, every 80 years) might not be a good idea. What if the paint has a memory, likr NiCad batteries, and inverts itself, three months after you apply it.

Personally, I would give it a really good stir with an electric stirrer, then use it. If it fails, it's not going to sink the boat. Ablative paint is not too difficult to remove, in the worst case. And how would you dispose it, if you don't use it?

Alan

[Wotname]

Originally Posted by AlanR

Inverting the cans frequently (not regularly; Halley's comet is regular, every 80 years) might not be a good idea. What if the paint has a memory, likr NiCad batteries, and inverts itself, three months after you apply it.

This only happens to flat paints, not full gloss etc

Personally, I would give it a really good stir with an electric stirrer, then use it. If it fails, it's not going to sink the boat. Ablative paint is not too difficult to remove, in the worst case. And how would you dispose it, if you don't use it?

Alan

Leave it unopened in any boatyard, it will soon be re-homed...

[hamburking]

I always buy bottom paint from the "clearance" section of the boat store...so I just assumed they were always very old. Takes a fair bit of stirring, but always seemed to work like new.

I learned early on that stuff like paint, acetone, and the really toxic stuff (cleaners) should be left at home. For weekend sailors and canadians this works just fine. If you are cruising, buy it just before you use it. Its difficult enough to store things like gasoline, diesel fuel, and stove alcohol on the boat!

Every boat I've bought has always included a locker or 3 FULL of cleaners and paints...almost always NEVER USED. I've found that people are very gung-ho to spruce up their boats when in the boat store...less so when the chore actually needs to be done. I've also found that if you don't power wash last years bottom paint off the hull, it actually lasts a few years. I'm sure the manufacturers are delighted to sell the same overpriced products to most boaters every single year. Canadian winter is just as effective as a power wash, and it leaves the bottom paint intact. Might not look as pretty as a shiny new coat, but I've had no complaints from the fish.

[hzcruiser]

Originally Posted by Jon Hacking

Manny, I don't know, but I wouldn't try.

[...]
But then we smelled the paint fumes and realized that we couldn't wake her up. So we carried her up on deck for some fresh air and looked after her as best we could. She eventually woke up about 24 hours later, and seemed fine. But a few years later she developed brain cancer and died, while still in her 20s. [...] .

Very sad story, Jon!

There is little doubt that paint thinner, like glue sniffing, damages the brain cells. Not sure if it relates to cancer, but better safe than sorry, of course!

I keep left over paint, thinners, deck oils, brushes etc in a large locker under the quarter berth and check it regularly (as in, whenever I need to touch up a bit of rust or re-do the varnish, hence at least 4 times a year).

Never had a can develop rust on the outside (or inside), the locker is perfectly dry. As for the contents, I sometimes get a pretty thick skin on top of the paint which I cut off with a long screwdriver, mix up the rest and use that with no noticeable ill effect.

If it's oil based I now pour a bit of thinner on top of the paint before closing the lid. I also put a layer of glad wrap over the can before closing the lid to make it more air tight.

[cooties]

Originally Posted by AlanR

Inverting the cans frequently (not regularly; Halley's comet is regular, every 80 years) might not be a good idea. What if the paint has a memory, likr NiCad batteries, and inverts itself, three months after you apply it.

Personally, I would give it a really good stir with an electric stirrer, then use it. If it fails, it's not going to sink the boat. Ablative paint is not too difficult to remove, in the worst case. And how would you dispose it, if you don't use it?

Alan

Originally Posted by Wotname

Leave it unopened in any boatyard, it will soon be re-homed...

I'm sorry - but one of you suggests paints have a memory from turning it in storage, and then Wotname says only some paints do. I mean.. what ?!?

[Wotname]

Originally Posted by cooties

I'm sorry - but one of you suggests paints have a memory from turning it in storage, and then Wotname says only some paints do. I mean.. what ?!?

Ahh...no!

I suggest any can of old unopened paint that is left unattended in a boatyard for awhile will soon find someone who is happy to give it a new home. I make no comment if the paint will be fit for purpose or otherwise .