Jotun Jotamastic 87 and orange peel

[Marky_Lad]

Agreed, as I pointed out earlier. Flat back the Jotun and lay a couple of coats of an automotive epoxy.

I better buy myself a compressor and spray gun

 

[ajlelectronics]

I better buy myself a compressor and spray gun

Look into the economics, if it is a one off, just hire it. Perhaps buy a decent gun though and we can make some suggestions there. I use a Devillbis GPi for larger jobs and a cheap Fast Mover FMT3006 for panels. You will want a 1.3 or 1.4 tip for the colour coats. A 1.8 is typical for primer but I have often put Lechler 29107 through the 1.4 with a nice smooth result.

 

[steveo3002]

or what are the other people that do these by hand using? maybe theres some primers that lay down smooth with a roller

 

[ajlelectronics]

or what are the other people that do these by hand using? maybe theres some primers that lay down smooth with a roller

I did one on the canal in the way I described. The owner had some admiring comments afterwards. One of the jobs was to cut off some roof rails with the plasma cutter, that was fed by the bollard too.

 

[Dcal]

What are you trying to achieve?

The Jotamastic is an industrial finish and is designed to go on thick and the appearance is secondary, but it is designed to last for many years if properly applied.
For the bits of the narrow boat that is always submerged I'd keep as much primer on as possible and wouldn't worry about the finish, I'd also apply more coats of Jotamastic and fewer undercoats and topcoats as the primer will be doing most of the protection.
Rolling won't normally give a high enough dry film thickness but if you put enough coats on you can get there.
Thinning with Thinner 17 will help application and improve the finish.
No undercoats and one or two top coats should be enough.
Are you applying an antifouling?
The Jotamastic will be fine under that without any more work.

For the bits above the waterline you can flat as much as you want to get the finish you require but you need to leave enough primer (of whatever type) to protect the steel.
I'm certain you have tried sanding too soon after application and another day or two will make all the difference.

If you over thin epoxy mastic it is pretty much a standard epoxy primer, but it's not recommended by the manufacturer.

I've had good results with Jotamastic 87 and 90 using a gravity gun with a 2.5mm nossle, heating the activated primer slightly and adding a good 10% thinner by volume.
The 90 certainly goes on flatter.

If rolling use a short pile roller and as much (or as little) thinner as you need and put on plenty of coats.
A cheap DPT meter is great for confirming you have enough paint on.

 

[Marky_Lad]

@Dcal, I used Jotamastic 87 with around 5% Thinner 17, I've applied it to the superstructure, the roof can have the orange peel effect as it's irrelevant given it's covered by solar and a rougher surface might aid grip when walking on it. Smooth sides and hulll and stern) are far more important. I think I'll have to sand it down and see where I do from there. A DPT meter is a good idea!

 

[Turbo]

Depending on how bad the orange peel is but you could spray on a few coats of a 2k filler primer over the epoxy and then sand that smooth. It will be a lot easier to sand.
There are probably automotive epoxy primers out there that will do a similar job.

I think somebody has suggested this already but get your primer tinted to the same colour as your top coat. It's a boat and it will get scraped and chipped.

As for airless sprayers, most users would struggle to get a flat finish with one. So if using it on your boat your orange peel is only likely to get worse!

 

[steveo3002]

would still want keying before any further coats of anything are applied

 

[Marky_Lad]

Thanks all, I really appreciate your input!

 

[Pigeon_Droppings2]

Depending on how bad the orange peel is but you could spray on a few coats of a 2k filler primer over the epoxy and then sand that smooth.

I was watching "How they do it" the other night....they were building a huge super yacht.

The paint prep....an army of guys slapping on barrels of epoxy filler. Apparently took them 6 months to fill and sand to get that sleek hull....I had no idea that's how they did it!

 

[fizzy]

Morning all,

I’m looking for a bit of advice with regard to an orange peel finish. I’ve primed by narrowboat with Jotun Jotamastic 87, this was rolled on due to time constraints and the fact that laying off with a brush really didn’t appear to provide a better finish. The boat has had three coats of primer which has left an orange peel texture. The plan is for 3 coats of undercoat, followed by 3 coats of topcoat. I plan to spray this using an airless paint sprayer. As the Jotun is an epoxy based paint it’s difficult to flat with sanding discs, these clog pretty quickly and this clogging is then spread to the surrounding area, might this be that it hasn’t dried enough in two days to cure properly?

Having no experience in painting a boat I’m unsure as to how best to proceed. Will 6 coats of sprayed paint leave a smoother finish or will it amplify the orange peel. Should I attempt to flat the primer before the undercoat, or flat it after the undercoat. I’m expecting some texture in the final coat but would like this to be reduced as much as possible. Any advice would be greatly received.

Mark

You only really need 1 or 2 coats. Epoxy paints like this have specific overcoating times. Ideally you apply a suitable compatible topcoat within that overcoating window. If you miss it you have to wait some time and then sand back. Much better to plan the painting and overcoating together. That way you get a chemical bond. when that window is passed you need a mechanical bond.

https://jotundatasheetsprod.blob.core.windows.net/ags/AG%C2%A4515%C2%A4Jotamastic%2087%C2%A4Euk%C2%A4GB.pdf

Look around page 7.

You have 3 months to overcoat with itself before you need mechanical prep. For acrylic paints you have 7 days or so. Past that time it can then be abraded.