Jump to content

Jotun Jotomastic 90 paint


Featured Posts

I am planning to paint the hull side or more specifically the bit above the rubbing strake and up tothe gunnel.  I have used various paints in the past but would like to try something a little tougher and have been looking at 2 pack paints.  

 

Some a very expensive indeed but Jotun Jotomastic 90 seems to be less so although it could not be classed as cheap.  It says it is semi-gloss and can be had in black which is what I would prefer or even near matt. Does anyone have experience using this paint product for this purpose?  Is it OK to use and hard wearing? 

Edited by churchward
Link to comment
Share on other sites

1 hour ago, churchward said:

I am planning to paint the hull side or more specifically the bit above the rubbing strake and the gunnel.  I have used various paints in the past but would like to try something a little tougher and have been looking at 2 pack paints.  

 

Some a very expensive indeed but Jotun Jotomastic 90 seems to be less so although it could not be classed as cheap.  It says it is semi-gloss and can be had in black which is what I would prefer or even near matt. Does anyone have experience using this paint product for this purpose?  Is it OK to use and hard wearing? 

 

I intend to do the same but have not done it yet. The only problem that I can think off is that it fades to grey over a year or two, it will still get some scrapes and so any repairs will be very obvious.  The rest of the hull is done in Jotun 87? and 90 and it performs very well.

Link to comment
Share on other sites

1 hour ago, churchward said:

I am planning to paint the hull side or more specifically the bit above the rubbing strake and the gunnel.  I have used various paints in the past but would like to try something a little tougher and have been looking at 2 pack paints.  

 

Some a very expensive indeed but Jotun Jotomastic 90 seems to be less so although it could not be classed as cheap.  It says it is semi-gloss and can be had in black which is what I would prefer or even near matt. Does anyone have experience using this paint product for this purpose?  Is it OK to use and hard wearing? 

Yes, I used SMLPaints for advice and I used it.

I mixed it and painted boat within six hours and all went OK.

It was perfect temp etc, if not ideal I would recommend using scales to make sure mix is correct 

Link to comment
Share on other sites

If you scrape concrete and stick out bits of iron you will scrape off whatever is on there. IMO use a cheap one pack black and touch it up as required, even bitumen 

Edited by ditchcrawler
Spilling
Link to comment
Share on other sites

I think it's about three years since I painted and apart from rubbing strips the hull and a rub on the bow it does not need touch up, this would be a problem if I touched up with two pack as you need to keep some airtight samples for this purpose, I just use any oil based paint or bitumen, not perfect, but most noticeable is discoloured waterline, with Jotamastic 90 not scrapes.

 

 

Link to comment
Share on other sites

10 hours ago, ditchcrawler said:

If you scrape concrete and stick out bits of iron you will scrape off whatever is on there. IMO use a cheap one pack black and touch it up as required, even bitumen 

Agree. I used something that claimed to be rust resisting from Screwfix. It was fast drying to a semi-mat finish that did not make the odd ding or scrape look worse, as gloss would. I think it was water based so the brush was easy to clean and it was easy to give that area a quick rub down and re-coat in an evening.

Link to comment
Share on other sites

I used ordinary gloss black paint a few years ago. It was terrible, it came off with the slightest scrape and the boat looked as though it had been steered into every bush, wall and bit of bank on the system. 

Link to comment
Share on other sites

10 minutes ago, Bee said:

I used ordinary gloss black paint a few years ago. It was terrible, it came off with the slightest scrape and the boat looked as though it had been steered into every bush, wall and bit of bank on the system. 

But it was cheap!

Link to comment
Share on other sites

11 hours ago, ditchcrawler said:

If you scrape concrete and stick out bits of iron you will scrape off whatever is on there. IMO use a cheap one pack black and touch it up as required, even bitumen 

Been there and done that with normal finishes over several years which is why I am looking for an alternative. I have seen two-pack applied to a friend's boat and it seems to be fairing well.  I agree it will not resist an impact with a much harder object but it does cope better with odd brushes with objects/vegetation compared to normal paint.

Edited by churchward
Link to comment
Share on other sites

53 minutes ago, Bee said:

I used ordinary gloss black paint a few years ago. It was terrible, it came off with the slightest scrape and the boat looked as though it had been steered into every bush, wall and bit of bank on the system. 

 

Yes, I am constantly rrepairing ours. The Jotun below the guard iron has done much much better. I realise that this is a lower impact area but even so it only has a couple of perforations after several years boating. I am confident that extending the Jotun above the guard iron will be a good thing.

Link to comment
Share on other sites

4 hours ago, Old Son said:

I used Jotun in this area and touched up scratches with Hammerite smooth. You couldn't see it unless you really searched.

Thanks that is a good thought and recommendation

Link to comment
Share on other sites

On 29/05/2023 at 21:33, ditchcrawler said:

If you scrape concrete and stick out bits of iron you will scrape off whatever is on there. IMO use a cheap one pack black and touch it up as required, even bitumen 

 

This is true. However, a good epoxy will have much better abrasion resistance properties than bitumen or any other paint so less will be scraped off in the first place. Also the longevity of coatings is not just about abrasion. Bitumen suffers from UV degradation.

 

On 29/05/2023 at 11:20, churchward said:

I am planning to paint the hull side or more specifically the bit above the rubbing strake and up tothe gunnel.  I have used various paints in the past but would like to try something a little tougher and have been looking at 2 pack paints.  

 

Some a very expensive indeed but Jotun Jotomastic 90 seems to be less so although it could not be classed as cheap.  It says it is semi-gloss and can be had in black which is what I would prefer or even near matt. Does anyone have experience using this paint product for this purpose?  Is it OK to use and hard wearing? 

 

Jotamastic 90 is available in a number of shades of black, however as someone else said it's subject to "chalking" which fades the colour. It doesn't change any of the other properties of the paint. If you a want a specific shade that doesn't fade I'd recommend Jotun Hardtop (2 part epoxy top coat)

 

Are you taking the top plank (the bit between the top rubbing strake and gunwale) back to bare steel or painting over what's already there? If it's the latter you're probably wasting your money with Jotun epoxies as any paint system is only as tough as it's weakest layer and also there may be compatibly issues. I heard of one epoxy which can be painted over single pack paints and even over bitumen without any compatibility issues called Ballistic epoxy (not to be confused with Ballistic blacking which is bitumen).

 

https://www.smlmarinepaints.co.uk/products/Ballastic_Epoxy

 

So it will adhere to single part paints and also to bitumen and you might get an improved tougher surface finish, but if it's painted over single part paints then that will limit it's ultimate toughness.

Edited by blackrose
Link to comment
Share on other sites

29 minutes ago, blackrose said:

 

This is true. However, a good epoxy will have much better abrasion resistance properties than bitumen or any other paint so less will be scraped off in the first place. Also the longevity of coatings is not just about abrasion. Bitumen suffers from UV degradation.

 

 

Jotamastic 90 is available in a number of shades of black, however as someone else said it's subject to "chalking" which fades the colour. It doesn't change any of the other properties of the paint. If you a want a specific shade that doesn't fade I'd recommend Jotun Hardtop (2 part epoxy top coat)

 

Are you taking the top plank (the bit between the top rubbing strake and gunwale) back to bare steel or painting over what's already there? If it's the latter you're probably wasting your money with Jotun epoxies as any paint system is only as tough as it's weakest layer and also there may be compatibly issues. I heard of one epoxy which can be painted over single pack paints and even over bitumen without any compatibility issues called Ballistic epoxy (not to be confused with Ballistic blacking which is bitumen).

 

https://www.smlmarinepaints.co.uk/products/Ballastic_Epoxy

 

So it will adhere to single part paints and also to bitumen and you might get an improved tougher surface finish, but if it's painted over single part paints then that will limit it's ultimate toughness.

I shall have to look into it further but the tech spec for Jotomastic says it is "surface tolerant" and "specially designed for areas where optimum surface preparation is not possible or desired."

 

I will take a look at the Hardtop product you mention, thanks. I see it is a full gloss product which is not the finish I was hoping for.

Edited by churchward
Link to comment
Share on other sites

Yes Jotamastic 90 is surface tolerant but that's chiefly referring to the surface preparation specification. For bare steel I think Jotamastic 90 requires a surface prep of ST2 or ST2.5. If the spec sheet mentions previously painted surfaces that's assuming the previous coating is compatible. I'm sure you can paint Jotamastic over most single part paints without compatibility issues but I'm just not sure what the point would be given what I said previously about the paint system only being as good as it's weakest layer.

 

Anyway, if you do decide to use it, before you buy it I'd give SML or another supplier a call and let them know which previous single part coating you're intending to cover.

Edited by blackrose
Link to comment
Share on other sites

10 hours ago, churchward said:

snip

... I see it is a full gloss product which is not the finish I was hoping for.

fwiw I agree that matt looks better. If you wanted to use it (the Jotun Hard Top), you may be able to add a matting agent to it, could be worth looking into.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.