Using 2 pack paints

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jams

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Hi all,

I'm about to embark on painting my yacht, from the ground up. I want to use 2 pack primers and topcoats (Jotun). However im about to break and use a single pack system due to all the variables that can mess up a 2 pack system, mix ratio, temp, humidity, etc etc.

So who has used 2 pack on their boats? Success....on not!? What went wrong if not?

Regards

Jams
 
I've used two pack varnish. No something I will repeat. Tough as old nails I grant you and lasted a good number of years but poor on gloss, unattractive and not good on adhesion when it gave up the ghost. When it failed it peels off in strips. Ugh!
 
I would use single-part on wood as it is more flexible.

I've used 2-part standard Awlgrip on GRP with a WEST System roller (and tipping with same) and got a glassy smooth finish.

I've also used 2-part Imron ..... only got a 3' finish ..... humidity was very low and the brushing thinner was called and accelerator! ..... it was supposed to flush the bubbles out quicker. On the whole: very difficult paint to use.
 
Pollyurethane paint

I have used commercial 2 pack polyurethane paints with a lot of success. They are meant to be sprayed but that requires breathing apparatus and sealed shed so I just brushed it on. In some cases I did not use primer but went straight onto gel coat (and repairs). I tend to get a lot of scratches on the hull and wear on the deck so I find it great for touching up. In fact the last pack of paint I bought is still usable after 3 years.
I have never been too fussy about mixing ratios. It seems to harden in an hour or so. (fortunately normally no problem with temp or humidity here). So my finish is hardly glossy but in the other hand is never allowed to look damaged or tatty. good luck olewill
 
G'day Jams,

I have used 2 pack paint many times and the oly problem I ever had was a couple of small runs that had to sanded back and polished out.

Best sprayed on, but beware, it does not go on like 'normal' paint, it can be very hard to see the wet edge and will be touch dry in minutes.

If you have limited experience with spraying, consider hiring a pro, the trick is to hire one to apply the paint only, that means you do all the prep, masking, mixing and clean up after.
The time required to paint an average 30 footer in under an hour, so it's not going to be a huge cost.

The other alternative is to apply with a roller and tip off with a fine foam brush, best done with two people, starting at the top and work down in overlapping strips, the length of the strip will determine the width as you need to keep a wet edge on the last strip.
Many thin coats will result in a super gloss finish that looks like it was sprayed.

Look for a polyurethane with long chain polymers, this gives good self leveling qualities.

And remember 80% of the work is in the preparation.

The above paint system should give many years of good service, the finish should be so smooth you can not get a pencil to mark it, like trying to write on a sheet of glass.

Good luck.
 
Jams, I just did my deck with Jotun 2 packs - Penguard HB primer (epoxy) and Hardtop HB (polyurethatne) topcoat. Mixing quantities less than a couple of litres is easily done with common or garden electronic kitchen scales (put them in a clear carrier bag to avoid enraging 'er indoors ;0) )- Shepherd Marine can send you a sheet detailing the ratios, which are sligthly different than by volume because of differing densities of the components. over 2 liters, get a few cheap kitchen measuring jugs.

Temp/humidity wise, I painted in a marquee in Cardiff in March. I used the Penguard Low Temp additive (It was on the bordeline 10 C mark) and it went off no probs. the epoxy primers will cure down to 2 C with the low temp additive. The polyurethane topcoats will cure down to zero degrees. (This all according to the technical specs, available on shepherd marine www) Of course, lower temps mean longer curing times. Humidity wise, I don't recall seeing anything specified, but you could simply wait for some dry weather if you're worried.

I rollered on the primer, and used a combination of roller and good quality brush for top coat. The finish is mostly good, but in places I didn't rub back the primer to as flat as it could have been, and the texture shows through. This is in part due to penguard HB being pretty thick and not very good at self levelling, as well as my lack of time in the tent.

N.B. You WILL need a chemical vapour mask.

edit: other's comments above about wood are quite correct, if you told us a bit more about your boat or filled in your profile that would help us help you!

Check out my blog for a some pics of the whole process
 
Last edited:
jams said:
Hi all,

I'm about to embark on painting my yacht, from the ground up. I want to use 2 pack primers and topcoats (Jotun). However im about to break and use a single pack system due to all the variables that can mess up a 2 pack system, mix ratio, temp, humidity, etc etc.

So who has used 2 pack on their boats? Success....on not!? What went wrong if not?

Regards

Jams
Click to expand...

Humidity or low temps can be disastrous for two packs: and if they don't go off properly you're left with a sticky half-cured mess that takes forever (in may case weeks) to dry. Been there, done that, lots of work to re-rub down and fix once it finally did harden. This was with International two-pack first time: re-did with Awlgrip which worked well, but I was more choosy about application conditions that time round.

The ones who're saying they harden fast are mostly in Australia !
 
that's a fair point, but if you leave well alone it's no prob. the primer I used took 5 or 6 days to harden enough to sand it back, but that wasn't a big problem in itself. Teh topcoat goes off in a matter of hours (or, as when I was doing the hatches this weekend, in about 2 minutes!)
 
Thanks for the replies. She is GRP, 50ft.

So i should be ok with the Jotun 2 pack, and no experience then?!
 
if you don't mind having a less than perfect finish, then go for it, just do what it says on the data sheets. Malcome at Shepherd Marine is eminently helpful.

If you're at all precious about a concourse finish, think again.
 
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