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frances doherty

Two part primer

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Morning.... I'm thinking of using Dulux Trade undercoat and top coat to paint boat. I have to take off holding coat of primer which has been on the boat for a while... So as I'm going back to bare metal I'm thinking of using a two part primer which I can get at trade. So I'd be really interested in anybodies experience of this... Applying it and advatages/disadvantages.... Thanks all! 

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Two pack is good, but more demanding with regard to temperature, R H etc.  Some of it is a CoSSH nightmare.  Read the data sheets and the hazard sheets carefully.  You really want a proper, ventilated, temperature controlled dock to do the job.

The primer is part of a paint system, so you should do the whole job in two pack.

Much of it is designed for spray application, and even the brushable stuff is harder to get a good finish with by hand.   The thinners can be expensive too.

Touch up in the event of a close encounter with a bridge hole or a vicious bramble can be much harder than with ordinary paint, but otoh the damage is likely to be less.

 

N

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1 hour ago, frances doherty said:

I'm going back to bare metal

When you say 'bare metal' using a 2-pack requires there to be absolutely no 'single-pack' paint. If you try and paint 2-pack over even the slightest 'spot' of single-pack it will bubble and blister.

You can put single-pack over properly cured 2-pack, but not the other way around.

 

I used Hemple 'High Build Primer' (High Protect)

 

https://www.hempelyacht.com/en-GB/products/hempels-high-protect-35651

 

It actually fills any small blemishes as well as acting as a primer and is 'good enough' to be used below the waterline as well as above.

 

£65 per 2.5 litre can, I needed 10 cans.

 

 

 

Screenshot (194).png

Edited by Alan de Enfield

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If you are doing a proper bare metal repaint then a proper two pack primer designed for use on steel would be good, but as BEngo says, doing it properly could be expensive. As you plan to use Dulux rather than proper boat enamel then it sounds like you are after a cheap job. Two pack done badly might be a mess and its very hard to sand out errors.  I am starting to think that the optimum paint job could be a sprayed two pack primer and undercoat with a brushed (single pack) enamel top coat, but then I have some unusual ideas about boats.

 

...............Dave

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'Back to metal' has always puzzled me. I can see the reason if you have a horrible rusty flaky mess but even then there will be patches where the paint is stuck on hard, Surely a well flatted surface of old paint is perfectly ok to start again with? I can see the point in removing underwater paint to start again with a different paint system and this would seem to be money well spent but as for the rest?  Perhaps I'm just a lazy bodger. Oh as for the original question, if you are going to go with two pack primer then do the whole job with two pack.

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25 minutes ago, Bee said:

'Back to metal' has always puzzled me. I can see the reason if you have a horrible rusty flaky mess but even then there will be patches where the paint is stuck on hard, Surely a well flatted surface of old paint is perfectly ok to start again with?

This question was about applying a two pack over an existing one pack system.

You need to take off all the one pack. The reason is in how these coatings work. The single pack usually relies on a primer (like red oxide) which pretends to do the job of red lead and passivates the surface so stops rust. The top coats then prevent water and air getting through ...sort of.

A two pack epoxy works a different way. Firstly the system is much more resistant to water/air getting through and secondly the adhesion of the coating is much much better. The coating tends to be harder, tougher etc. If damaged, the adhesion protects against undercutting so damage doesn't spread. These are barrier coatings rather than passivating coatings.

If you put the epoxy over an old coating, the potential is that the adhesion of the original coating is much lower than the epoxy and if any stress on the top coating, it will pull the old one off, hence allow rust to start. Even epoxy over old epoxy is a bit of a risk if there is any doubt over adhesion. Epoxy over single pack is not good even if the old alkyd coating doesn't blister as the adhesion will just not be good enough.

Take the old single coat system back to bare steel......preferably by grit blasting to the right standard to get a mechanical key.

 

 

 

eta. Red lead followed by multiple alkyd single pack top coats is the best solution. Shame it's so difficult to get hold of ( i.e. Banned).

Edited by Dr Bob

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16 minutes ago, Bee said:

'Back to metal' has always puzzled me. I can see the reason if you have a horrible rusty flaky mess but even then there will be patches where the paint is stuck on hard, Surely a well flatted surface of old paint is perfectly ok to start again with? I can see the point in removing underwater paint to start again with a different paint system and this would seem to be money well spent but as for the rest?  Perhaps I'm just a lazy bodger. Oh as for the original question, if you are going to go with two pack primer then do the whole job with two pack.

It depends on the finish you want,  and the risk you have in the work.

The old patches of paint will take lots of work  to hide, in a shiny finish.  Easier to start from bare metal if shiny is what you want or the customer expects.

As the painter, do you want/can you afford to rely on the bond of the existing paint to the metal, particularly at the edges of rusty patches or damage? Is the new paint compatible with the old?   If it fails will you have to sort it, at your expense?  If it is your own boat, then you may be happy to take a chance.  If you are a professional then bare metal may take more work but is less risky.

N

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47 minutes ago, Bee said:

Surely a well flatted surface of old paint is perfectly ok to start again with?

There are HUGE warnings in the data sheets, as I wrote in post #3

 

1 hour ago, Alan de Enfield said:

If you try and paint 2-pack over even the slightest 'spot' of single-pack it will bubble and blister.

 

PRODUCT APPLICATION:

...........................….thoroughly cleaned and on previously coated surfaces, ensure all old paint layers are removed. Fill and fair where necessary. Then apply 2
coats of the product at 150 micron dry film thickness each. Steel: Apply a minimum 3 coats of each 150 micron dry film thickness.

 

APPLICATION CONDITIONS : The surface must be completely clean and dry at the time of application and its temperature must be
above the dew point to avoid condensation. Do not apply in direct sunlight. In confined spaces provide
adequate ventilation during application and drying.

Edited by Alan de Enfield

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Chaps ..... In reply to some of the comment's ;

I have to take off the coat of primer which is on there.. As primer is porous... But there is no other paint on there. 

I'm not using Dulux to do a cheap job.... There are many boaters who think it is as good as the expensive boat paint... And from my point of view a much better range of colours as I'm not a tradionalist. Plus... I have a Brewers near me who can mix the colours as and when I want. 

I want to do the best job possible which is why I was thinking of two part... However it sounds trickier than some of the other, I am sure, very good primers... Including dulux metalshield probably.... So thanks for your opinions....especially those with experience 

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We use a two part-paint system on Emily Anne, from what was Leighs paints, now owned by Sherwin Williams, epoxy ali primer, and a acrylic urethane under and topcoat. The boat was shot blasted from new and treated with a two part blast primer within hours of the prep, because it was a new boat and one way to remove the mill scale. Some boats are made with pickled and oiled steel, but a lot are still not, in which case the scale needs to be removed, mechanically or by allowing it to rust off.

 

While bright steel is a good starting surface for the right paint, unlike the suggestions above it it not the only way to start a two-part paint system, you can allow the steel to develop a light rust, which is otherwise clean is a great key, but it can also be applied over most existing paint systems as long as the surface is stable. One of the exceptions being a bitumen blacking type coating, which might be where the confusion has come from as often two-pack on narrowboats is used below the waterline where bitumen is another common product.

 

There is more faff to applying a two pack, we put ours on with a decent grade 4 inch foam roller, cut in at the edges with a brush, and get a very nice uniform coating, if not polished enamel type finish. You can do it on your own, but at very lease for the finishing coat if painting outside in summer its good have someone mixing it 1 litre at a time and supplying it fairly continuously so you can maintain a good wet-edge. You struggle to apply it in this currently unseasonal heat too, but that would go for almost any paint system.

 

I used Dulux Trade 'Metalshield' on the boom and dipper of my digger five years ago based on success with there trade 'Weathershield' woodwork paint on window frames etc and sadly would not use it again.  The zinc phosphate primer was a total pig to put on, and the gloss topcoat (red) has chalked very quickly and some areas of rust have come through again as well. I got a better finish and durability with Blackfriars QD90 which was cheaper and easier to apply. I then did the rest of the outside of the machine top coat with a cheap brandless 'quick dry enamel' from the local agricultural supplies place because QD90 wasn't the right share of red. Despite designed being design for spraying went on fine with a brush and looks better than the Dulux.

 

 

Daniel

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Thank you Daniel... Thats exactly what I was looking for... And a good tip about the metalshield. I think I will probably go for another recommended primer to use with the dulux under/top coat. Maybe I'll try the two part next time if I get a chance to grit blast then... I can't do it this time as I'm in a boat yard without those facilities. 

I know the dulux Weathershield will be OK as many boaters seem to be really pleased  with it... But you're the first person who has experience with the metalshield. 

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We know that proper boat enamels do a good job because professional painters use it, we have seen the results, and we know it usually lasts a long time. If you use a non-boaty paint then you have to rely on a few people who have used it and say its good. But people have different standards and boaters are an odd bunch who like to think they have made a good decision and done a good job. I know a boater who had did their own sign writing, it looks terrible, but they are proud of it and honestly believe its a top job. Also some boaters, myself included, like a non pristine result

 

If you don't want to use boat enamel then what about tractor enamel from a farm shop? Farmers like good value but also take no s**t, so farm stuff is usually a safe bet, this sort of fits in with Daniels observations. A bare metal paint is a big job but also good opportunity. If you phone Craftmaster today you can probably have the paint by Thursday.🙂

 

.....................Dave

  • Greenie 1

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20 years ago I used Witham oil and Paint trading as Woco paints and found it very long lasting, well as good as the first profesional job I paid for. What there paint is like now I dont know but they have a good colour range https://www.withamgroup.co.uk/

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Argh... Another paint company in the mix.... I'll have to continue looking and reading. I do want a good paint job... But pristine I'm not worried about.. I would pay if I wanted that. I'll be painting designs all over it anyway.... Decisions decisions :)

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13 minutes ago, ditchcrawler said:

20 years ago I used Witham oil and Paint trading as Woco paints and found it very long lasting, well as good as the first profesional job I paid for. What there paint is like now I dont know but they have a good colour range https://www.withamgroup.co.uk/

 

Their oils are very good as well, they have a number of Vintage & Classic grades as standard (they even have oil for steam engine cylinders) andwill make up any grade your engine requires, even if it dates back to Noah's Ark.

 

They even do the difficult to find API-CC oils that many of our old boat engines require.

 

https://www.withamgroup.co.uk/shop/classic-range/

 

Their HQ is just up the road from me, and I note they have a branch in Lowestoft as well.

 

 

Screenshot (195).png

Edited by Alan de Enfield

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9 minutes ago, frances doherty said:

Argh... Another paint company in the mix.... I'll have to continue looking and reading. I do want a good paint job... But pristine I'm not worried about.. I would pay if I wanted that. I'll be painting designs all over it anyway.... Decisions decisions :)

and another one then.... Teamac is a well respected boat enamel and at the cheaper end of the (boaty) price range. If you do use a boaty paint then a bit of additive can make the process a lot easier, especially in this hot weather. A lot of people use Owatrol but I prefer the "proper" PPA stuff from Craftmaster.

 

If you are going to the trouble of painting designs on top then that's another reason to do a good solid job underneath.

 

................Dave

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3 hours ago, Alan de Enfield said:

 

 

 

Their HQ is just up the road from me, and I note they have a branch in Lowestoft as well.

 

 

Which is why I used them

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3 hours ago, dmr said:

and another one then.... Teamac is a well respected boat enamel and at the cheaper end of the (boaty) price range. If you do use a boaty paint then a bit of additive can make the process a lot easier, especially in this hot weather. A lot of people use Owatrol but I prefer the "proper" PPA stuff from Craftmaster.

 

If you are going to the trouble of painting designs on top then that's another reason to do a good solid job underneath.

 

................Dave

I've just looked up the Teamac... And it looks good and the price is reasonable too... But.. Like all the other specifically boat paints it doesn't have a huge range of colours.... I'm very fussy about my colours... I'm in the business of colour. ;)

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1 hour ago, frances doherty said:

I've just looked up the Teamac... And it looks good and the price is reasonable too... But.. Like all the other specifically boat paints it doesn't have a huge range of colours.... I'm very fussy about my colours... I'm in the business of colour. ;)

A kindred spirit. I am still trying to determine the perfect shade of blue.

Craftmaster will supply any colour you want but you have to send them a sample, so you need to get or make this, and it can take some time to get it analysed.

Also, looking at colour charts is useless, you need to paint a sample on the side of the boat and look from various angles at different times of the day etc.

You can mix your own little samples, and then mix your own pots of paint. I have spent the last week doing exactly this 🙂

For mixing samples get the closest colour you can and adjust it with a bit of something else, once you get the hue right black or white are useful to change the "lightness" and saturation. Little plastic pots are good for mixing and a set of "drug dealers" electronic scales (about £5 on eBay) allow very precise mixing of small samples. A spoon wrapped in tinfoil is a good paint ladle. Its almost fun. I think I have got the shade I want and now have some paint on order (arrives tomorrow) to paint a bigger test area.

If you mix your own I think you have to invent a name for it.🙂

 

.................Dave

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2 hours ago, frances doherty said:

Thank you.. I was going to use owatrol but I'll look up this one too 

Forgot to say, I tried Owatrol but it was a long time ago. I think it gave lovely paint flow and wet edge but I felt it extended the drying time quite a bit. Fast drying is good when working outdoors, less time for the insects, pollen and everything else to land on the paint. The helps the flow but I think without significantly extending the drying time.  Both have interesting smells.

 

...............Dave

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Thanks for all the info.... You can go round and round eh? I think after a lot of deliberation and conflicting advice... I am going to go with one of the recommended boat primers.... Dulux Trade under/top coat (I need 7 colours... And their range is brilliant, the colour theme of my boat is Indian summer.... You won't be able to miss it. Also I need a specific pink... And I know from being a ceramic sculptor.. That it is almost impossible to mix pink correctly ) and I'll use the oil you advised. Look out for me next year on the cut with your sunglasses on! 

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20 hours ago, dmr said:

Forgot to say, I tried Owatrol but it was a long time ago. I think it gave lovely paint flow and wet edge but I felt it extended the drying time quite a bit. Fast drying is good when working outdoors, less time for the insects, pollen and everything else to land on the paint. The helps the flow but I think without significantly extending the drying time.  Both have interesting smells.

 

...............Dave

I don’t get this. Surely the point of such an additive is to enable you to keep a wet edge? And that process equals a slower drying time?  What am I misunderstanding?

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18 minutes ago, WotEver said:

I don’t get this. Surely the point of such an additive is to enable you to keep a wet edge? And that process equals a slower drying time?  What am I misunderstanding?

I don't understand paint technology, maybe Dr Bob will help. You need a low enough viscosity for it to flow nicely, and if its thick and stodgy the additives certainly help, then I suspect the solvent, or maybe solvent mix, needs to evaporate at the correct rate. A perfect paint would stay wet long enough to maintain a wet edge on a typical paint job, and then dry quickly. I have noticed, for example, that Rylards is different to other paints, it flows nicely, then almost dries quite quickly but then stays a bit tacky for ages, the first two are good features, the last is less good.  I guess what I am trying to say is that we want a non-linear drying curve, or at least an initial delay phase!

 

Ive been doing quite a lot of paint repairs during our lock down and hot weather painting is interesting, PPA has really helped, a very small amount makes a huge difference to the paint flow. Painting Incralac on a hot day was the most difficult till I discovered cellulose thinners.

 

...................Dave

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