Antifoul mk II

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Sailfree

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I am using Micron extra and every year it was wet scoured with a green scouring cloth and another coat applied with two coats at waterline and front edge of fin, rudder and bow.

I am now suffering from a thick buildup and various problems which I have described in another post - and my mistakes!

However the question on this thread - is antifoul toxic and works all the way to the bottom of any thickness applied ?

My understanding is that Micron Extra is a hard antifoul but self eroding.

I ask as I am wondering whether the answer is yes and hence if you can't see the gel coat don't apply more? Or the surface becomes neutralised and inert and the top layer must be either removed or over coated each year for it to work?

I am beginning to think that we may all be brainwashed into buying and applying too much antifoul if it is toxic throughout its depth hence the questions.
 
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The International paint manual says that Micron Extra gives protection for 24 months with minimum paint build up, washes away with use. Obviously if it lasts 2 years it doesn't wash away that fast! The quick reference chart claims it is excellent for lasting more than one season but it is listed as 'Polishing' and not 'Hard'. So whoever is brainwashing you it is not International. :D
 
Sailfree said:
My understanding is that Micron Extra is a hard antifoul but self eroding.
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A few years ago I was in Bangor Marina and using Micron Extra. There's a stream enters the marina, and before they solved the sewage problem, this meant a thin layer of fresh water at the surface with ... erm ... extra nutriants. Result was a lot of weed just at the waterline although not much elsewhere.

I tried given the waterline a quick scrub from the dinghy and went straight through the Micron Extra to the primer. That would've been four coats of Micron Extra applied two at a time about 12 months apart.

So I wouldn't call it that hard.
 
Sailfree said:
But is it toxic and effective all the way to the bottom or does only the top surface work and become neutralised with the exposure to salt water?
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My understanding is that the active ingredients dissolve/disappear as the antifoul erodes a few microns so constantly exposing good surfaces until it's all gone. Using a hard antifoul on a slow boat can leave the top layer ineffective after a while as there's little or no erosion.
 
I have always used micron. Just come out today and after 2.4 years there was only a liitle slime. Very impressed as it was only 2 years previously. I am pleased i changed the colour last time as its obvious its warn through in some places which suggests the timing is about right. Clearly the last two coats have eroded off and the antifouling from 2.4 years ago is still working as these areas were no different. This years shes black so hopefully there will be blue patches next time around.
 
There are 2 main types of antifouling. Hard and eroding. In both types the biocides (usually cuprous oxide boosted with organic biocides) are mixed into a paint matrix. The paint matrix in a hard antifouling is designed to be long lasting and to stay in place while the biocides leach out into the surrounding water. At first the biocides are coming out from close to the surface of the paint and will be very effective but as time goes on the surface will be leached out and the biocides have to come from further back in the paint layer where the water is more static. The leaching rate reduces and the antifouling is less effective. A hard antifouling with the biocides leached out will become friable and crumbly over time and will flake quite easily unless the loose material is removed before recoating.
An eroding antifouling is designed for the paint matrix to dissolve into sea water or, in some types, crumble away into the water. The process continually releases fresh biocide into the water from the remaining surface layer of the paint so these types will generally work better for longer than a hard antifouling. Once the active layer is worn away, of course, it will suddenly stop working as there is no active biocide left.

Micron Extra is an eroding antifouling so slowly dissolves away into the water.

The simple answer to your question Sailfree is that an effective biocide is available in your antifouling right to the back of the paint film. Unfortunately, however, that is not the whole story!

All antifoulings are porous. They do not form a waterproof barrier coat like an epoxy or, to a lesser extent, like a gloss paint. They are designed to stay soft in the water and if they are left out for a prolonged period they will dry hard and not be able to erode in the same way when re-immersed. If you antifoul at the beginning of the season and launch the boat the antifouling will erode effectively, and if you touch it with a sponge or a scrubbing brush you will see clouds of paint drifting away in the water. At the end of the season when the boat is lifted and pressure washed a lot of antifouling will be washed off. After a winter of standing ashore, if you pressure wash again the antifouling will wash off at a much slower rate as the paint resin has hardened and cannot be reactivated in the same way as before.

The eroding rate for an antifouling is key to it's service life. The trick for you is to put just enough onto the hull each season so that it finally disappears as you go to have the boat lifted, then you have no waste and a fresh layer at the start of each season. Impossible to do, of course as you don't know how much you will use the boat each year, how fast you will go, and anyway the water flow varies at different parts of the hull.
The trick for the paint company is to make an antifouling that erodes quickly enough for the very slow water flow over most yacht hulls and that will keep working for the extended period when the boat is static in a marina. We need high biocide content and fast erosion rate compared with what is put onto a cross channel ferry, or a container ship, where the vessel is moving all the time and at a much higher flow rate than a yacht. This is why you should ignore the people who talk about putting the "good stuff" from commercial ships onto yachts.
All antifoulings are a compromise but you get what you pay for in terms of the biocide cocktail included, colour quality, length of time you can leave before immersion along with a series of other factors.
Then, of course, there are variables like differing growth rates for fouling in different years, shell versus weed fouling, water temperature variation, salinity variation, agricultural run off into our waters etc etc etc.

For most of us its a case of choosing the antifouling that suits our budget, putting enough on so that there are no bare patches at the end of the season and accepting that occasionally we will need to clean off the build up of dead paint on the hull. Plus choosing the product that seems to best suit our particular environment over the last few years.

Going back to your original thread on this subject, the dust from any paint that is dry sanded is toxic but antifouling dust is more toxic than other paints. If you breath it in, or other people down wind breath it in, it's not going to promote long life!

Hope this helps
 
Pasarell said:
We need high biocide content and fast erosion rate compared with what is put onto a cross channel ferry, or a container ship, where the vessel is moving all the time and at a much higher flow rate than a yacht. This is why you should ignore the people who talk about putting the "good stuff" from commercial ships onto yachts.
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Good explanation about antifoul except that I disagree with the bit above. Personal experience with a sailing boat sitting on a mooring with tide running past (not in still marina waters) has been that years ago, TBT was the best around and these days Jotun Seaforce (still available here) outperforms all so-called yacht antifouls.
 
I can't comment on Seaforce specifically as I've no experience with it but all antifoulings are designed for a particular purpose based on speed and activity of the vessel, and the biocide cocktail varies by price and manufacturer. Maybe Seaforce is meant for the coastal market like tugs and other harbour vessels. Much lower speed and lower activity than larger ships and closer to the activity of yachts. Just speculation but that could be why some people here found it performed well.
TBT performed at a completely different level to current antifoulings but unfortunately it also damaged the marine environment at a whole different level as well. The way it was banned was handled very badly in my opinion but there was no doubt the residual TBT in coastal waters from yachts and small craft was far more damaging than that released from ocean going vessels. It was possible to formulate products that were truly polishing rather than the eroding ones today and to be far more targeted with release rates for different speeds. When a large ship was stationary in harbour there was virtually no TBT release at all but yachts had to be leaching a lot more to stay clean because they were static for so much of the time.
I yearn for the performance of TBT as much as anyone but recognise it came at a very high price to the marine environment most of us want to protect. I haven't seen any studies for a few years now but about 10 years or so ago there were still very high levels of TBT in the mud in Ocean Village, nearly 20 years after it disappeared for yacht use. The mud at the container port in Southampton contained virtually no TBT even though large container ships had been docking with TBT antifoulings only a couple of years before.
Like I said in my previous post all antifoulings are a compromise in formulation and leaching rates, and fouling growth and types vary widely around the coast. Selecting the best product for you is not a predictable exercise but with time and experience you can get an understanding of what works best in your area most of the time.
 
Thank you Pasarell for the information.
As I read it, for those of us in sailboats kept in static water marinas (as opposed to fast flowing rivers), we don't need to recoat with new eroding a/f as often as those in fast flowing water. If we are getting a thicker coating building up year on year then we are painting too much on. I particularly like the thought that it should have virtually eroded by the time we get to annual lift-out. Lastly I had not realised that the old coat hardens and dies in the open air. So the long winter haul out is bad news.
Luckily this year my yacht has been in the water all winter, and is only coming out for one week for repainting etc. Will be interesting to see thickness of a/f compared with thickness of weed on liftout!
Peter
 
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