Do I need to undercoat prior to antifouling

[Sneaky Pete]

Sorting out the antifouling just now while the boat is out of the water I have never done this before. So antifouling on hull is flaking in places power wash removed some of the old antifouling. I am now rubbing down many years of paint with a Shurhold scourer and some wet n dry paper the pics show where I am at just now the hull is smooth. The gel coat areas white in the pics the question is this should I put an undercoat/base layer then apply antifouling or can I apply antifouling directly onto the gel coat.

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[Cloven]

Sorting out the antifouling just now while the boat is out of the water I have never done this before. So antifouling on hull is flaking in places power wash removed some of the old antifouling. I am now rubbing down many years of paint with a Shurhold scourer and some wet n dry paper the pics show where I am at just now the hull is smooth. The gel coat areas white in the pics the question is this should I put an undercoat/base layer then apply antifouling or can I apply antifouling directly onto the gel coat.



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Absolutely you should use an antifoul primer first. If not, there is every chance that the antifoul will just flake off. I would also suggest using the same brand primer as the antifoul; so there is no chance of incompatibility.

 

[sarabande]

most anti-foulings recommend a base coat of something like Primocon. They act as an additional waterproof barrier to the gel coat, and make the surface really smooth.


Did you mention that you were using a mask and eye protection ? ...

 

[Sneaky Pete]

What I have been using is a sugar soap solution with the scourer and water with the wet n dry there is no dust from this and a running hose every couple of minutes to examine the progress.

Thanks for the advice on the base layer.

 

[Caer Urfa]

Hi Pete

Without doubt I agree with others and put a coat of primer on BEFORE antifoul, (I always do it)

I used to use Primocon but try this from Jotun Paints http://www.smlmarinepaints.co.uk/primers/single_pack/vinyguard-silvergrey-88

We checked out the specifications against Primocon and they are almost 'like for like' BUT much less cost and you get bigger tins!

We also use their Seaqueen antifoul, if you look on the site you can buy complete kits. primer,antifoul and thinners and save more.

Apply with small 4" 'sponge' type roller (not the furry one!).

Happy painting

Mike

 

[Plevier]

Hi Pete

Without doubt I agree with others and put a coat of primer on BEFORE antifoul, (I always do it)

I used to use Primocon but try this from Jotun Paints http://www.smlmarinepaints.co.uk/primers/single_pack/vinyguard-silvergrey-88

We checked out the specifications against Primocon and they are almost 'like for like' BUT much less cost and you get bigger tins!

We also use their Seaqueen antifoul, if you look on the site you can buy complete kits. primer,antifoul and thinners and save more.

Apply with small 4" 'sponge' type roller (not the furry one!).

Happy painting

Mike

+1, excellent stuff, but I can't find foam rollers that don't dissolve in the a/foul they last about 10 mins! This includes the ones SML supply. I find short pile ones (like mohair) best.

 

[Caer Urfa]

+1, excellent stuff, but I can't find foam rollers that don't dissolve in the a/foul they last about 10 mins! This includes the ones SML supply. I find short pile ones (like mohair) best.

Yes I know what you mean, however I have been using some of the spongy ones from B &Q and they come in a pack of ten.

Mike

 

[BAtoo]

+1, excellent stuff, but I can't find foam rollers that don't dissolve in the a/foul they last about 10 mins! This includes the ones SML supply. I find short pile ones (like mohair) best.

+1 for Jotun primer & AF.

Once you have the surface clear and smooth to your satisfaction I would do the whole hull with a coat of primer, including any bits of AF that are left.

I use the fat foam 4" rollers from B&Q and can get about half the hull (31ft) done before they give up.

When I had more money I used Primocon & Optima which didn't eat rollers.

 

[kjones744]

If you use solvent resistant rollers you'll be fine or use solvent free paint. A great solvent free bottom paint is Monterey by SeaHawk. Since it is solvent free it is more difficult to mix but well worth it not to worry and approved for some of the locations where solvents are prohibited.

 

[Plevier]

My dissolving rollers were labelled solvent resistant. They ain't Jotun proof though!

 

[Sneaky Pete]

Thanks to all for their advice. What I am going to use is Hempel Tiger Xtra only reason for using it was that it was recommended by an owner who was applying it to his boat and because Hempel the name/business is no longer the chandlery was selling off their stock at half price. Can anyone tell me if it is good practise to thin down this antifouling paint it does say on instructions that it can be thinned by 10% are there any benefits to this especially in the colder weather.