Jotun Hardtop AX

[aquaholic]

So I am at that stage of my project where I am thinking about which paint to use on topsides, deck and cockpit, after considering different options including flowcoat and single pack paints I have decided to go with 2 pack polyurethane and have been looking at the Jotun range, especially their new Hardtop AX Top coat.

Does anyone have any experience of this paint, I am told that it is easier to apply than others as it has better wet edge properties.

 

[Uno]

Jotun's Hardtop AX is very new and seems to have been developed for both ships, large structures, buildings and bridges ect.
Why on earth would you use it on a Contessa yacht.
It is not a pure Polyurethane rather its an Acrylic Polyurethane with an Aliphatic Isocyanate hardener so you will most likely find the drying too fast to brush and roll, even with the slowest of thinner types( it will possibly still be shiny but Acrylic/Poly's don't usually flow out as well as pure polyurethane types especially when they have a development criteria for ships and structures). I am sure the wet edge you will have heard about is better than the previous Hardtop but not anywhere near to a Yacht type paint wet edge.
Don't blame Jotun if it looks **** ... Blame the person that told you it was good for a yacht !!
See the below section from their datasheet:
Hardtop AX
Product description
This is a two component chemically curing aliphatic acrylic polyurethane coating. It has a gloss finish with
excellent gloss retention. It has good chemical resistance. It is a tailor-made version based on new construction
application conditions. Used as a topcoat in pre-qualified NORSOK systems. To be used as topcoat in
atmospheric environments.
Colours
according to colour card
Typical use
Marine:
Recommended for topside, deck and superstructure.
Protective:
Recommended for offshore environments, refineries, power plants, bridges and buildings. Suitable for a wide
range of industrial structures. Used as a topcoat in pre-qualified NORSOK systems.

 

[afterpegassus]

I can only agree with the above - having learned the hard way.
I used Hardtop XP three years ago on my topsides and despite my best efforts, was left with a surface similar to fine corduroy where you could see every vertical brush stroke.
Putting these efforts down to inexperience, this spring, I had another go with no expense spared on thinners, brushes and rollers and the result was much the same - the stuff was going off before it had time flow.
I will not use it again

 

[aquaholic]

Thanks for your thoughts, which I have passed to the distributer for comment, can you suggest an alternative?

 

[aquaholic]

OK so I have received this response from the distributor, all things considered I am going to give AX a try and see how I get on. Will post results.

"Your correspondent is correct in stating that it is much easier to keep a wet edge with pure Polyurethanes that with Isocyanate cured Acrylic Polyurethanes, typical of the Hardtop range.* If you are painting the freeboard, where it is likely that the wet edge is less than a metre in length, it will be possible to achieve a good finish with hardtop AX.* Typically two people would paint in a co-ordinated way - the first person rolling using a foam solvent resistant HD roller and the second person laying off immediately with a good quality brush.** Ideally you need to paint in windless, cool conditions.* Any brush marks can be compounded out once the paint has fully cured.* For cabin roofs and other areas where there is likely to be a long wet edge, spraying is a preferred option.

The gloss and colour retention of the Jotun products will be similar to the much more expensive Pure Polyurethanes marketed for DIY yacht finishing.*** We have many customers who get excellent results using the Jotun products, but we also have occasional customers who do not get good results.* It is the case that a higher degree of skill is required to get the same result when using Jotun 2 pack polyurethanes."

 

[bds]

I have just painted the boat I am making with Hardtop AX, so I can give some insight here.

The boat is 30 feet long, with low freeboard, so it is quite a small area and quite manageable on my own. The boat is plywood, but sheathed and heavily epoxied. The primer I used was Penguard HB.

My first attempt with the AX was a disaster. I intended to use the 'roll and tip' method with a helper, so I bought 4" foam rollers and decent 2" and 3" brushes. I tried initally to use it unthinned, but this was a very clear non-starter - by the time it was rolled to a consistent thickness with the foam roller (only a few seconds) it was much too stiff and sticky to tip with a brush. Unfortunately thinning with the supplier's recommended thinner - number 18 I think - did not improve matters. We tried 5%, 10% and 15%, and all were unsuccessful. The problem here was that the rolling inevitably led to a thinner layer, which was probably below the specified coat thickness anyway, but what I gained from the extra wetness, I immeditely lost by the coat being thinner - i.e. it still dried off much too quick.

The next attempt was no better: The supplier switched me onto thinner number 10 (which is the manufacturer's official recommended thinner) and fibre rollers. Sadly the same results ensued.

To be fair, when I reported this back to them they not only put me in touch with a professional boat painter who was very generous with his advice, but they sent me *his* suggested thinner and rollers at no charge. I was very pleased with this gesture, and in the end I got a result that I was very happy with.

Here's how:

I was advised to use thinner number 12, and in quite generous amounts. This thinner is actually designed for a different product - the Megagloss I think - but it works perfectly well with AX, and is much slower. I thinned with 20% by volume, which sounds a lot but this is much less by weight.

In addition I was advised to abandon foam rollers in favour of 4" fibre rollers with short fibres to facilitate getting enough paint onto the job. Also, my friendly painter suggested abandoning the tipping. Obviously with hand application, you are never going to get the same finish as spraying - effectively you choose brush marks or the texture you get from a roller. It would certainly have been possible to brush out so you may prefer to opt for the brush marks, but personally I found the roller texture rather good. It is pretty fine - much finer than on the first attempts - and from only a few paces back just seems like a 'satin' finish as opposed to high gloss. It also looks a lot better dry than wet, so it is quite forgiving even if you are not 100% happy when it's wet. There was sufficient time to roll out very evenly, but I did need to take care not to be too fussy and overwork things - once you stray into paint that is no longer part of the wet edge, it tends to pull fibres out of the roller. I pretreated the rollers first as a precaution, by wrapping masking tape round them and pulling it off again to remove any loose fibres.

I am very pleased with the result, but I think it is very likely there are easier products for hand finishing. I does not flow and self-level as well as some paints, but with a slow thinner it is not too difficult to get an attractive and even result, albeit not a perfect mirror finish.

Hope this helps someone.

 

[aquaholic]

Thanks for your experience, weather depending I should start with the top coat at the weekend so will post back with my own results.