Two-pack painting

[Michael Rogers]

Has anyone any experience of HMG paints (a Liverpool-based firm, who do an apparently extensive marine range)? Warning - getting a proper look at their wares on their website is a bit of a Fort Knox experience: you need to apply for a password. Funny way to try to sell stuff?

More generally, has anyone pearls of wisdom on two-pack (non-spray) painting which they are itching to pass on to novices (of which I am one)?

[LASER41420]

Hi,
we have done lots of two pack painting using International and Blakes products, for the best results you need two painters, one to apply with a roller and one to tip off with a foam brush. It help to use thinners and the paint softens, and then disintegrates, both roller and brush after about 20 minutes. Work fast and have spare tools ready. What are you painting?
Steve & Sue

[Paul H (admin)]

I agree with Steve's comments. Here are some more issues:

Jotun two-pack uses a heavy solvent and the neighbours 4 houses away noticed the smell, so pick a windy day or a sociable time to paint.

Don't paint in direct sunlight or a hot day, the skin will form too quickly.

You need to be a confident and skilled painter to use a brush - one extra stroke can ruin the finish. Otherwise stick to a foam roller, which will slowly melt and soften after 30 minutes.

Mix small quantities as the window of opportunity is small. The paint will thicken after 20 minutes and becomes harder to apply.

Its impossible to clean it off brushes or your hands. You have to wait several days for your skin to regrow.

Epoxy two-pack undercoat seemed to be the most important layer. It bonds extremly well to washed and sanded epoxied ply.

A few places I forgot the undercoat and the two-pack polyurethane top coat is not so strong.

Be careful that all the wood joints are bonded well with epoxy to avoid hairline cracks.


However, MilliBee's paint looks good after 6 years with no degradation.....apart from inevitable bumps and scrapes.

-Paul

PS. I bought Jotun 2-pack from a local paint specialist.

[LASER41420]

Acetone will usually get it off skin, better to use gloves though!
Steve

[Michael Rogers]

Thanks, guys, that's all very helpful. Not quite at the painting stage, except that one or two places, such as inside storage lockers, need doing before the decks go on, which is imminent. I have the dagger board and rudder components finished, so those might be small areas to get an initial feel for 'roll and tip' technique. We live down a country lane, and if my painting pongs a bit sometimes, that will be a modest return for the rich aroma of slurry-spreading which comes our way from the beef farm next door (we are, I hasten to add, on the very best of terms with our neighbours, and their steaks are something else).

My (kit) build is a Swallowboats Trouper 12. All my impressions from pictures are being confirmed as she comes together. She is beamy so should be stable as my 'dotage boat' (I'm several years on the shady side of seventy). She has lovely lines, really gorgeous with sheer strake tumble home to a slightly curved transom. Matt Newland admits that she is a bit under-canvassed with the rigs he offers, so I am increasing sail area with - no prizes for guessing what rig!

Michael

[Chris Waite]

I have to agree with just about everything that has been said above

It's a seriously durable finish, slightly tougher than old nails, that you normally rehash after most of a decade, largely because you fancy a different colour; amazing how the paint perists, but we mature.  Beats the hell out of repainting every year or two with conventional paints and I think the expense is worth the freedom and probably balances out the initial cost in the end.

In my experience of a series of five boats, roll it on, noting that foam rollers do disintegrate (they go squidgy-soft, then start to tear and snooky little foam crumbs stay on the surface) after some minutes to half an hour - a small roller soaks up less paint if it's a dinghy; yes you need to tip it off with a brush, though once you get to know what it's thinking, you can actually take a swipe and a half again very lightly with the roller itself instead - this mostly pops the inevitable bubbles.  Then LEAVE IT - do not be tempted to touch it after five or ten minutes, the result is much, much worse than anything you have already perpetrated.  Cool dry weather is best - heat and sun cut down the fiddling time dramatically.

I have used Jotun (OK if you own a destroyer - small quantities can be hard to come by), Blakes (excellent as are their colours and price), Epihanes (not cheap) - all very good; so is International, though their recent colour charts have things like three shades of Nearly Navy (Mauritius Blue, Flag Blue, Royal Blue actually) and nothing obviously yellow, red and green for instance; their 'Cream' is mushroom and their 'Fighting Lady Yellow' is cream.  I think their chief mixer has a cataract problem - well Monet did and his colours went totally wierd, or was that Manet?  I had some other stuff once and it was worse than trying to get a gloss finish with a foam bath and a yard brush.  I also go top coat (two coats can often do) straight to sanded epoxy and have never used any primer, or undercoat -  I think Paulie's 'Millibee' went for a roll in something oily

When he wasn't looking

CW

[Anders]

So, how about painting 2 pack polyurethane with a brush (no roller) directly on epoxy resin? Is that a way to go.

[Jeremy]

I tried painting the International 2 pack with a brush years ago and found it difficult.  It tends to dry out quickly and doesn't seem to like being brushed out, making it hard to keep a wet edge.  The foam rollers, although short-lived, were quick enough to allow an area to be covered without this problem, although you have to avoid the temptation to go back over an area already painted.

The finish I obtained with just a foam roller on the coach roof of my old boat (which was ply covered in epoxy glass) was surprisingly good, almost as if had been sprayed, and it was incredibly tough.

[Chris Waite]

Painting two pack polyurethane with a brush is possible and I do it for all the awkward little the edges (under the gunwale, into corners and that sort of thing) before picking up the roller, but as Jeremy says you get a much more even finish if you can roll it working rapidly.

Like cheap wine, it doesn't do to let it hang around

CW

[Paul H (admin)]

Painting 2-pack with a brush can be a nightmare, if a good finish is required over a large area OR the weather and time constraints are against you.

Conventional gloss is thixotropic - as you work the paint it thins and flows nicely to produce a mirror like finish. But 2-pack behaves quite differently and if you work the paint too long it can thicken quicker, which is exactly the opposite to what you need for a good finish.

That's why the manufacturers recommend spraying 2-pack and at a pinch rollering works because it applies several thin layers and each layer does little damage. The net result is reasonable but you won't get a mirror like finish.

As I said before I believe you need to be a competent, skilled painter to use a brush - there is nothing user friendly about 2-packs paints and very little tolerance for errors. My Grandfathers and Dad where good painters and taught me well from an early age, but I found it quite stressful using a brush with 2-pack. You have to learn a whole new technique very quickly using a brush, but a roller is less risky.

Also a 14ft-16ft hull is a huge area to paint - its incredibly slow with a brush and the chance of doing a whole side without brush marks is impossible. Hence the roller is universally better, plus a gentle lay-off with a brush if you know what you are doing and the paint responds well.

-Paul

[Anders]

Ok, thanks. Brushing is no good.
 Then another of my short questions:
 
¿Why these foam rollers that fall apart? Cant it be these wolly ones that last a lot longer?

I once painted the roof of a GF caravan with one of the wolly ones and it didnt fall apart.

[Chris Partridge]

All this just goes to confirm my opinion that the best paint is water based exterior paint. So you have to touch it up every so often - it is still less trouble (and far, far lee stressful)....

[Jeremy]

Anders wrote

Ok, thanks. Brushing is no good.
 Then another of my short questions:
 
¿Why these foam rollers that fall apart? Cant it be these wolly ones that last a lot longer?

I once painted the roof of a GF caravan with one of the wolly ones and it didnt fall apart.

The solvent in the 2 pack makes the foam expand and go soft and squidgy, after 1/2 hour or so the foam starts to break up.

I've not tried a woolly roller, but generally these aren't recommended for gloss paints, I believe (not that I'm in any way an expert!).

[Michael Rogers]

I've had some interesting comments on this from Andrew Freeman, who builds Swallowboats under licence in Tasmania. (The finish he gets is absolutely superb, but I believe he sprays!) He suggests that if you're prepared to spend the time and money, you can get a spray-equivalent finish by 1) roll-tipping plenty of topcoat (an extra coat?) on without too much concern about brush marks, 2) wet sanding with 1800+ grade wet-and-dry, 3) finishing off with a cut and polish preparation (presumably something like T-Cut for cars?). He claims you won't be able to distinguish between the result and that from spraying. Sounds like lots of work (and lolly), might be worth it in the long run. I plan to give it a go, initially on smaller areas like the dagger board and rudder blade. Will report.

Michael

[Anders]

What about painting the interior on a dinghy. You have to paint centerboard, below seats and other things where its difficult to reach.
Do you still use 2 pack paints and do you use a small roller?

I´m going to paint soon and I cant see myself using 2 pack on the interior. To stressy. I might use 2 pack on the outsides.... I personally dont care much about that superperfect glossy look. On clinker boats I actually prefer a satin look (BTW) this you can get by wetsanding with 2000 and later with 4000 micromesh pad)

[Paul H (admin)]

Anders,
For MilliBee's cabin interior I brushed vinyl silk emulusion! For the cockpit under the gunnels only a brush fits, but brush marks look ok there. Seats and cockpit floor were 2 pack roller, brush for internal corners.  

Sent from my HTC

[Chris Waite]

I did all of 'Tit Willow' with two part polyurethane inside and out

Basically brush where you must and roll when you can.

The interior was quite intoxicating.  I seem to remember polyurethaning the whole inside of the hull before decking her over, then finally going in for the kill to paint the deckhead, while pretending not to breathe.

Quite what was killing who I cannot recall, but I did have to keep taking my liver out and rinsing it through with alcohol to revive it.

I would have thought given half a chance woolly rollers would moult with the pull of the rapidly drying paint

Isn't that what the Great Sod would decree?
 
Cee Dubbaya

[Anders]

Again thanks. I´m learning something here.

But... Just a wee question more. How does 2pack polyurethane go with 1pack urethane varnish. Isnt it something about a story with 2pack not working on top of 1 pack or is it the opposite or is it just me know nothing, I´m from Spain?

In my build, it would be me first varnishing seats, part of the interior, gunnels and rubbing strake on the outside. This i would do in order to seal the wood and not getting any paint deep into wood pores. Then I would paint and finally, I would varnish again.
Would that be possible with 2 pack polyurethane paint and 1 pack urethane varnish?

[Chris Waite]

Anders

I've found that two-part polyurethane sticks to almost everything I have tried including old conventional oil based paint, (I'm not sure about one-part polyurethane).

However, nothing successfully sticks to two-part.  I tried one-part over two-part matt on the cockpit sole and seats where there has been a lot of traffic with some wear and it just won't play at all.  This may have something to do with two stroke outboard fuel having been spilt in the area some years ago, but I think it is more about incompatability.

So my experience indicates nothing apart from re-painting two-part over two-part

Hope this helps

Chris

[Paul H (admin)]

Anders,

It is not wise to use 2-pack over 1-pack because the underlying coat will not be as strong as the topcoat. 2-pack stands up well to thermal expansion in the sunshine and resists chipping, but 1-pack does not. So the 1-pack undercoat is likely to degrade before the 2-pack topcoat......you might lose the benefits and be wasting time and money on the top coat.

Jotun do a very useful high-build 2-pack epoxy primer (Jotun Penguard HB Primer). It is thick and builds up the surface to cover grain and scratches quite well - it also bonds extremely well to epoxy and is suitable for sealing potable water tanks. You can paint it inside metal water tanks for example:

http://www.baysidemarine.co.uk/product/Jotun_Penguard_HB_Epoxy_Primer_Grp%7CAlu_5Ltr_JOTUN-0822

Data sheet:
http://www.jotun.com/jotun/paints/20020020.nsf/0/da02a1c289d6a5b0c125671a0044e980/$FILE/TDS%20-%20Penguard%20HB%20-%20English%20(uk)%20-%20Issued.26.11.2010.pdf

It was an excellent primer for MilliBee. I sealed all the wood with epoxy, sanded and washed before using the Jotun HB primer.

cheers
Paul