Changing antifoul types - is internediate barrier coat really needed?

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West Coast

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Hi all, as launching sesson approaches, `i am shopping around for best antifoul deals. My boat has only ever had International Cruiser 250 applied, but willing to consider alternatives and so I am following other antifoul threads accordingly.

Different manufactureers advise not to paint one manufacturers type directly over another, rather paint a barrier coat in between. Is this really necessary in peoples experience?

Cheers!
 
I have had one bad experience with a covering af that was supposed to be compatible but generally no trouble with different grades from the same maker. It doesn’t do any harm to use a barrier if you are unsure.
 
In desperation to find an antifoul that actually works I've chopped and changed antifoul brands and formulations several times and never experienced any problems with adhesion after a light wet sand and pressure wash of the previous coating.

Manufacturers of course would much prefer you to continue using their products rather than swapping to a rivals so introducing the suggestion that the additional cost and hassle of a barrier coat will be needed for anybody wishing to successfully apply a antifoul from a different manufacturer is a good way of keeping their own bottom line healthy.
 
I've used various antifoulings without any trouble, but every year I wet sand the boat's bottom, so the new stuff is always going on to a sound and stable surface.
 
How would anyone know.

Manufacturers of AF produce products with different characteristics, eg hard or ablative. Different manufacturers use different resin systems, with different additives, biocides.

its a lottery.

My guess might be right, or not.

In this specific case I'd telephone (or mobile phone) International, Hempel etc and ask their recommendation. International will be able to advice which of their formulations will be compatible - and if they say 'barrier coat' take their advice and do as recommended. Other replies may be tinged, or not, wth bias.

Report the responses and you might get a more educated reply, here.

Most surface coating companies have a technical department - use it - if you buy their product - you pay for it. Why ignore a resource you pay for. Stress when you phone you have used Cruiser 250 - exclusively.

As I say - report back (that's why you are a forum member).

Jonathan
 
Neeves said:
How would anyone know.

Manufacturers of AF produce products with different characteristics, eg hard or ablative. Different manufacturers use different resin systems, with different additives, biocides.

its a lottery.

My guess might be right, or not.

In this specific case I'd telephone (or mobile phone) International, Hempel etc and ask their recommendation. International will be able to advice which of their formulations will be compatible - and if they say 'barrier coat' take their advice and do as recommended. Other replies may be tinged, or not, wth bias.

Report the responses and you might get a more educated reply, here.

Most surface coating companies have a technical department - use it - if you buy their product - you pay for it. Why ignore a resource you pay for. Stress when you phone you have used Cruiser 250 - exclusively.

As I say - report back (that's why you are a forum member).

Jonathan
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Well, obviously if you contact a paint company, they will encourage you to buy more paint whether it's needed or not. All I know is that with good preparation, I've never had any problem using different paints.
 
NormanS said:
Well, obviously if you contact a paint company, they will encourage you to buy more paint whether it's needed or not. All I know is that with good preparation, I've never had any problem using different paints.
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Your experience is what the OP is looking for.

What AF do you use, and have used?

Jonathan
 
Some years ago I used nine different a/f paints in consecutive seasons. There was never any reaction between old and new and as far as I could tell no effect on performance, such as it ever is these days.

The only problem I noted was that successive paint over one with a high PTFE content seemed more susceptible to flaking.
 
I've put anything and everything on many boats including commercial and have never had any issues.
In the days of tbt, a/f paints did not like mixing together but for at least the past 20 years I've never come across any issues or come across anyone that's had issues.
I used to antifoul a lot of customers boats for a chandlery who had scrubbing grids. Had leftovers of many different brand and types so poured them all into a bucket and ended up with a strange brown colour. It was free so why not? It worked just like any other a/f without any problems.
One year i used what was left in each can and ended up with a multicolored dazzle effect using the cheapest 5hrough to the most expensive. At next drying out session the whole hull had an even coating of weed. It was then i decided that expensive fared no better than the cheapest.
Location of boat makes the biggest difference to longevity, even a different mooring in a harbour can change how well the a/f lasts.
Many a/f state at least 7 hrs drying before immersion. Do it between tides and its immersed way before 7 hrs yet still seems to work ok and not fall off.
 
The only issue I experienced where I applied an atifoul over an antifoul which contained PTFE .

I remember phoning Blakes and they said it was probably a good idea to apply a tie coat. In the end I gave the hull a good wet sand with P60 grit and everything turned out OK.
 
I have cast iron bilge keels on a Westerliey Chieftain. I was also working with a nig operator for many years with easy access to marine paint reps and technical departments.

Firstly it is NOT a barrier coat that may be required but a tie coat. There is a possibility of some paints not adhering to some other paint surfaces and for a number of reasons. It is good practice to use a tie coat between them and I have done this for about 40 years . During this time I have used various antifouls with a tie coat between. When I started this it followed stripping the keels back to bare metal and every winter applying a tie coat and antifoul. To my surprise not only did this treatment ensure a reasonably effective antifoul but also the rate of corrosion to the keels was drastically reduce. I put this down to the tie coat I was using doing not only acting as a tie coat which according to the manufacturer it is suitable for this purpose, it was also carrying out another function that it was designed for even though it was not being applied directly to the cast iron keels. The strange thing is that if the coating is feathered down over an area then after a few years you would expect to see alternate layers of red and grey. This is not the case . No grey appears. Maybe a puzzle for some one to solve.

The grey paint is Primocon and this process also works on cast iron down pipes around the house togethrr with your favourite colour paint.
 
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Thanks all - really helpful as always! I also do a light sand to the previous years coating

Going to visit local chandlers to see what deals are going..........
 
MikeBz said:
I would say don’t put hard over soft, but otherwise as long as the surface is prepped I wouldn’t worry about changing products.
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This is sound advice, both from the product staying on the bottom of the boat, and the inevitable evil day when you have to strip it back. The stripper will stop at each hard layer…. I could elaborate on how I know, but I’m sure people can guess. I wouldn’t have minded one, but I reckon the previous owners had switched every 3 years for the 18 years since her first launch.
 
Chiara’s slave said:
This is sound advice, both from the product staying on the bottom of the boat, and the inevitable evil day when you have to strip it back. The stripper will stop at each hard layer…. I could elaborate on how I know, but I’m sure people can guess. I wouldn’t have minded one, but I reckon the previous owners had switched every 3 years for the 18 years since her first launch.
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When we stripped mine after quite a few years we were removing several layers at a time. Maybe this was the tie coat working to its death. ;)
 
West Coast said:
Hi all, as launching sesson approaches, `i am shopping around for best antifoul deals. My boat has only ever had International Cruiser 250 applied, but willing to consider alternatives and so I am following other antifoul threads accordingly.

Different manufactureers advise not to paint one manufacturers type directly over another, rather paint a barrier coat in between. Is this really necessary in peoples experience?

Cheers!
Click to expand...

Look for a compatibility chart. I've changed many times without trouble BUT I always use the paint up, scrub hard before hauling, power wash, and give it something better than alight scratch sanding (remove about one layer and anything even remotely loose or questionable).

Differing manufacturers are ALWAYS going to say that. CYA.

4 years ago I was testing paints for an article. I had 40 paints on pannels and 6 on my boat. The base on the boat was Petit SR40 and two of the tested paints were hard paints, two brands. No problems, no tie-coat. But good surface prep. Coarse paper. Spend a few hours with a good sander (in the US it would be a vacuum sander).

And no, do not use epoxy barrier coat as the tie coat in any event. It's not for that.
compatibility-chart-22-uk.png
 
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