2 pack virgin seeks info

[BruceK]

I`m about to do my first polyurethane 2 pack painting, mainly touch ups and repainting a couple of teak fittings already in 2 pack. I read the paint label instructions, I will use a high quality brush,I know thorough mixing is a must and to allow adequate drying time so the gloss won`t be lost, but was warned of getting it wrong first few times, which I`d like to avoid. Any hints, info, experiences appreciated.

 

[bshanafelt]

lots of info in the archives including;

http://www.trawlerforum.com/forums/s32/painting-topsides-3097-2.html

 

[Delfin]

I`m about to do my first polyurethane 2 pack painting, mainly touch ups and repainting a couple of teak fittings already in 2 pack. I read the paint label instructions, I will use a high quality brush,I know thorough mixing is a must and to allow adequate drying time so the gloss won`t be lost, but was warned of getting it wrong first few times, which I`d like to avoid. Any hints, info, experiences appreciated.

Big subject. In summary, here is what I have learned by doing:

1. Use the right primer.
2. Use the right thinner; spray for spray, brushing for brushing
3. If you use a brush you have a limited amount of time to coat before the product will start to kick. Best to put a heavier coat on, brush to flatten and keep moving.
4. For medium areas of less than 1 sq foot or so and especially for smaller areas, an airbrush is a great investment. Don't use masking, just sand the overspray with 2000 wet and dry, then rubbing compound in three grades, ending up with swirl remover. Done right, you can blend it perfectly.
5. Lighter colors are much more forgiving than dark colors, so adjust your expectations accordingly.

Good luck.

 

[FF]

Find a helper and roll and tip.

To do this successfully it takes a good enamel roller and a varnish quality brush.

Do it right and few if any will be able to tell it from a good spray job.

 

[Hendo78]

Hey Bruce,

How big are these parts you want to coat? and are you able to remove them?

If they are under 1200mm long, I'm happy to spray them in 2pac clear or any finish you like. Just post them over and ill do it and send it back. If its only a couple of items then it probably wouldn't be financially viable to buy all the gear and not use it again, but it's up to you, the offer is there.

If you want to do it yourself, you really can't go past spraying. It may take longer to set up but if you have the equipment I'd spray. Much better finish. I've been spraying 2pac for over 10 years and its a much better and consistent finish. You need to change the viscosity of the coats when you spray but two/three coats would be sufficient.

If you don't have the gear and can't send it over and want to brush it then get a good quality split end hair tip brush. Don't bother cleaning the brush as you will never get all of the 2pac out of the hairs.

Sent from my iPad using Trawler

 

[Hendo78]

Best to put a heavier coat on


Good luck.

Ok but from my experience, several lighter coats is more advantageous for a beginner and structurally sound for the material. You'll get more slumps and sags doing it in one thick coat. You also run the risk of crazing and/or cracking the face due to the surface setting before the rest of the coat has dried and resultant movement of the underlying coat ensues surface deformation. Kind of like overspray. Overspray is the fine paint of whatever you're using drying in the air before they hit the surface. A technique I was taught was to lightly spray thinners on the over spray which will melt the overspray into the coat. It's easy to put too much on and fu#k it up so if you've not tried that before, give it a go on a sample piece. Once you get the hang of it you'll be pleasantly surprised.

I'm not knocking your method as Everyone has their own way of doing things and whilst I have done it this way before, you really need to know how to read the material and you only get this through experience and the right gear.

I assume you have the experience Delfin so this may work for you which is great but Bruce has not done this before so IMHO I think it would be better for him to do lighter coats as opposed to doing one thick one.

As for the airbrush idea, you would really need to thin it out so you would need to apply a fair amount of coats to get the required coverage.

As for no masking tape ... Hmmm i don't see the advantage of spending an extra couple of hours buffing, polishing and cleaning everything in your vicinity when you could tape it up. Sure you'll get a paint edge but this can easily be fixed and blended.

I know it seems that I'm picking the sh!t out of your suggestions so please don't be offended. It's not my intention to offend you or pick your suggestions to bits. I just have a fair bit of experience in commercial 2pak spraying and am sharing my learnings from previous failures.

Whatever you choose to do Bruce, I'm sure it will look lovely!

Sent from my iPad using Trawler

 

[Delfin]

Ok but from my experience, several lighter coats is more advantageous for a beginner and structurally sound for the material. You'll get more slumps and sags doing it in one thick coat. You also run the risk of crazing and/or cracking the face due to the surface setting before the rest of the coat has dried and resultant movement of the underlying coat ensues surface deformation. Kind of like overspray. Overspray is the fine paint of whatever you're using drying in the air before they hit the surface. A technique I was taught was to lightly spray thinners on the over spray which will melt the overspray into the coat. It's easy to put too much on and fu#k it up so if you've not tried that before, give it a go on a sample piece. Once you get the hang of it you'll be pleasantly surprised.

I'm not knocking your method as Everyone has their own way of doing things and whilst I have done it this way before, you really need to know how to read the material and you only get this through experience and the right gear.

I assume you have the experience Delfin so this may work for you which is great but Bruce has not done this before so IMHO I think it would be better for him to do lighter coats as opposed to doing one thick one.

As for the airbrush idea, you would really need to thin it out so you would need to apply a fair amount of coats to get the required coverage.

As for no masking tape ... Hmmm i don't see the advantage of spending an extra couple of hours buffing, polishing and cleaning everything in your vicinity when you could tape it up. Sure you'll get a paint edge but this can easily be fixed and blended.

I know it seems that I'm picking the sh!t out of your suggestions so please don't be offended. It's not my intention to offend you or pick your suggestions to bits. I just have a fair bit of experience in commercial 2pak spraying and am sharing my learnings from previous failures.

Whatever you choose to do Bruce, I'm sure it will look lovely!

Sent from my iPad using Trawler

No offense taken - it sounds like you have a lot of experience.

A couple of observations for clarity...

When I say thick, I mean a properly thinned paint applied with sufficient millage to allow the material to flow and flatten. Too thin results in conspicuous brushmarks and worst case balling if you try to work it flat with the brush. Overworking 2 part polyurethane is a mistake.

I have used Awlcare as overspray barrier that wipes off, but it only takes minutes not hours to buff out the overspray from an airbrush so sometimes I don't bother. I use an airbrush because it provides control and precision paint placement. That's what they're designed to do and I thin the paint about the same as I would using other equipment. The only difference is I take longer to put on the same amount of paint but with better control. The technique is pretty simple. Prepare the area and make sure it is sanded flat, flat, flat. Prime, and wipe off overspray with Tuolene. Next day, wet sand the area with 2000 grit, then top coat. Spray until the area you are wanting to cover glistens, and ignore the area around it. Wait a couple of minutes and lay another coat on. Wait a couple of minutes and lay another coat on. Wipe off some of the overspray. Next day, wet sand the overspray off with 2000 grit, then buff with compound, and finish with swirl remover. The result is an invisible repair.

Hard edges from tape work fine for me in some places, but I would rather not have them in other areas, so it's just a matter of preferences.

 

[pauloman]

two part polys (actually lpu coatings - google lpu) are not user friendly and are best applied by spray. To hand application google "roll and tip" - must be applied in multi thin layers. Thick layers result in solvent entrapment. most problems with 2 part polys are the result of putting on too thick. Also they really like a fresh epoxy primer, their weak link is their adhesion..

 

[Delfin]

two part polys (actually lpu coatings - google lpu) are not user friendly and are best applied by spray. To hand application google "roll and tip" - must be applied in multi thin layers. Thick layers result in solvent entrapment. most problems with 2 part polys are the result of putting on too thick. Also they really like a fresh epoxy primer, their weak link is their adhesion..

I can't verify it, but I was told by someone who worked there that Feadship applies all their lpu coatings by brush. Hard to imagine, but that is what he said and he was one of their project managers.

 

[FF]

Feadship applies all their lpu coatings by brush. Hard to imagine, but that is what he said and he was one of their project managers.



Read all about it in Professional Boatbuilder

 

[BruceK]

Thanks for all the help. Finally doing it, small touch up repairs really, but good experience, and I`m just brushing it due to the areas involved. Epoxy undercoat done, topcoat tomorrow. Maybe I should have added thinners, the u/coat didn`t like me going back to "lay off" as with conventional paint. That is the main issue so far, apart from messing about mixing correct proportions, though shipwrights I`ve seen mixing didn`t seem precise measuring quantities. Depends what I find tomorrow. I know to leave a 6 hour drying window so I don`t lose the gloss, tomorrow will be dry and 30C, great for watching paint dry.
I can see roll/tip would be good for larger areas, a good finish, and no masking up for spraying.

 

[FF]

Epoxy undercoat done, topcoat tomorrow.

The hardest part of this exercise may finding a topcoat system that will stick to cured epoxy.

This chemical dance has gotten easier over time , but still sometimes the hard part of a repaint.

 

[Hendo78]

Thanks for all the help. Finally doing it, small touch up repairs really, but good experience, and I`m just brushing it due to the areas involved. Epoxy undercoat done, topcoat tomorrow. Maybe I should have added thinners, the u/coat didn`t like me going back to "lay off" as with conventional paint. That is the main issue so far, apart from messing about mixing correct proportions, though shipwrights I`ve seen mixing didn`t seem precise measuring quantities. Depends what I find tomorrow. I know to leave a 6 hour drying window so I don`t lose the gloss, tomorrow will be dry and 30C, great for watching paint dry.
I can see roll/tip would be good for larger areas, a good finish, and no masking up for spraying.

Glad ya got it sorted mate!

 

[Nomad Willy]

The part I like about this thread is "virgin seeks".

 

[BruceK]

Not easy finding a catchy thread name. Sure beats "single vs twins".
Today went well , except for spilling the mixed paint on the 6 week old teak deck, the bad language, and the clean up.
The undercoat and topcoat are from the same maker.Topcoat flowed well, better than the undercoat which went on later in the day on a warmer surface and probably went off faster, and I used a better brush.
I won`t need a second coat, but a tip from a shipwright is if you leave a second coat of 2 pack non slip beyond 24hrs, it won`t stick. Anyone know if that applies generally to 2 pack work?

 

[Hendo78]

I don't understand what you're asking. What's the Question exactly?

 

[BruceK]

I don't understand what you're asking. What's the Question exactly?

Last paragraph Hendo. Is there a time limit for applying brushed second and further coats of 2 pack so it will adhere? Like spraying "wet on wet"?
Hope that`s clearer.

 

[Hendo78]

Last paragraph Hendo. Is there a time limit for applying brushed second and further coats of 2 pack so it will adhere? Like spraying "wet on wet"?
Hope that`s clearer.

Ah. Depends on ambient temps, material Bla Bla Bla.

Some materials don't like wet on wet and will craze if you spray a thinner based coating on top of another that's has flashed off. Also when brushing, if you try and do a wet on wet, the brush will stick to the flashed coat leaving a mess and .... well ..... yeah ..... not cool.

Look i could be wrong and It may work perfectly fine but I'm just going off what I've seen over the years and not your particular job so only you can say for sure

IMHO, Just play it safe and let it dry between coats. All you're saving doing it wet on wet is sanding anyway. It doesn't make the coats any stronger. Better to sand between coats than sand off coats due to crazing.

Hope that's some help to you mate?!

 

[JAT]

When painting with 2 part poly's you let the coat dry then wet sand...lightly and do it all over again....

 

[Delfin]

When painting with 2 part poly's you let the coat dry then wet sand...lightly and do it all over again....

True with brush, not so much with spray, which should be applied as soon as the prior coat has flashed.

 

[JAT]

True with brush, not so much with spray, which should be applied as soon as the prior coat has flashed.

I stand corrected, sir! I should have noted that!!