question on paints for different jobs

Discussion in 'Boatbuilding' started by leaky, Mar 23, 2016.

  1. leaky
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    leaky Senior Member

    Hi,

    I'm in the process of painting my 26 foot seawolf (white fiberglass, aluminum bracket, & outboards).

    It had real cosmetic issues on the hull after I had done some work and only half-*** gel coated half the boat (the half I worked on :) ). I now have it smoothed out, cleaned up, and we have been tipping and rolling benjamin moore P22, which is a urethane/oil base we have had good luck with on other boats and it's coming out great..

    I could use the urethane stuff for everything but what I found is that it rolls very poorly, even with penatrol in it; I tried a few types of rollers, but it always gives you a finish with a bunch of little air bubbles/blobs. Much worse then what you get with regular oil or water base paint. And for some of the stuff I gotta do I want to roll it, I'd like that bit of texture to the finish and not to have to tip it, but I don't want the air bubbles.

    So anyway here's the list of things I have to paint.

    Engine bracket - currently coated with awlgrip but has been worn off in some spots, do most things stick to sanded awlgrip or is something special needed? I'm tempted to sand it and cover it with the urethane. This will be rolled and tipped as I'd like it to shine.

    Inside cabin - It had a series of 2 inch holes in the cabin for something that was mounted that's now gone. I did the repair/filling/fairing but it's kinda wavy and I don't want to spend hours block sanding this sort of thing. Also it's real hard to see because of the spot, but I don't want to put a real shine on it to accentuate the flaws and I want to roll it. I'm tempted to get a semi gloss or flat water base that's made for floors (so it's tough) and use that. Is that a reasonable idea or is there something else I should consider? Gel coat?

    Outside cabin - I'd like to roll this, it's gel coated now but has enough surface imperfections (unless I want to go nuts doing body work, which I do not) it's practically going to look better with the roller pattern showing through than trying to make it shine. Was thinking either similar water base as the inside of the cabin (but maybe a gloss) or gel coat.

    Deck that runs around cabin - thinking I'll use whatever the side of the cabin gets but it's going to have non-skid in it. One thing that makes me lean a little toward gel coat on this versus water base is the surface is real imperfect, has some peaks & valleys from prior glasswork. I could fill/fair some and then roll to remove them, but with gel coat I also can lay it on real thick and it will fill in some of that stuff naturally where as with paint it likely wouldn't dry right if I put it down 1/8 inch thick.

    Or maybe there is another urethane or oil based product out there that rolls OK I should consider instead for all areas where I'm not going to tip it?

    I have learned, after getting a lot of advice regarding water base and not following it, that the stuff does hold up great. I'm on the 4th year w/ my skiff that has a water base porch/floor paint over the epoxy on the deck and the stuff is holding up perfectly, at least as good as oil paints I've used before.. But still figured it'd be good to ask in case there is something better to use for this stuff.

    Thanks in advance!

    Jon
     
  2. gonzo
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    gonzo Senior Member

    What kind of roller do you use?
     
  3. leaky
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    leaky Senior Member

    In my latest test I tried foam and 2 different types of short nap - basically on the nap I buy the highest quality thing they seem to sell at the paint store and try a couple brands version. The foam seems to do about the best but maybe there is something better?

    Jon
     
  4. PAR
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    PAR Yacht Designer/Builder

    If you use a roller, you have to tip off, if you want a reasonable finish. The roller make bubbles by it's nature and can't be avoided. A modest cut and Penatrol will help, but the roller is going to do its thing, regardless of how short the nap is. Foam rollers are better, but still make bubbles. One technique that works is to place your finger on the roller as you make the last stroke across the area. If you use a light touch, it'll tip off pretty well and if the paint has good self leveling qualities, it'll look much better, without the bubbles. Why don't you consider spraying? Even a cheap hand shaker gun will produce better results, than a roll and no tip paint job.
     
  5. leaky
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    leaky Senior Member

    Thanks again PAR! You have helped me so many times on this site.

    The bubbles I'm complaining about are funny air bubbles I've never noted before, like they have an open end to them somehow, and I've only seen this happen with that urethane. Like you wouldn't even want to coat a deck that way because the paint basically has holes in it - does that make sense? Somehow the air gets trapped and it makes a bubble that opens up on top and doesn't level out. At the same time, when it is tipped by someone who is good at it (not me but my buddy Dave, I'm just the roller guy ;) ) one would almost think it was sprayed.

    The gel coat & water based I've rolled is not a smooth surface but it's a sane coat of paint minus the funny pattern - the way latex in a house has a pattern but looks OK. In the cabin I kinda want the imperfect paint pattern to help hide the imperfect surface, outside I guess I could have it shine as it's not bad to begin with, so maybe I will tip it. But what do you figure I should go at it with for paint if I was just gonna roll it? That was basically my question, which paint to pick. Maybe you are saying buck up and tip it with the same urethane.

    God spraying though - you are 100% right on the finish generated but I definitely couldn't do it in the cabin, just too much stuff to tape off without the cloud finding it's way on it eventually, outside I could spray but it'd be a lot of taping/plastic. Just too much stuff going on in this boat. Much more practical to the quality level I need if I roll/tip on the big spots and tip on the small areas and/or where I gotta cut.

    Jon
     
  6. PAR
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    PAR Yacht Designer/Builder

    The open bubbles are just popped bubbles. What percentage of Penetrol are you using in this stuff?
     
  7. leaky
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    leaky Senior Member

    I put 1/2 gallon of paint in a separate container, measured out about 16 ounces of penatrol, and we added it until the paint flowed right which was someplace in between 8-16 ounces.

    Jon
     
  8. PAR
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    PAR Yacht Designer/Builder

    That's a pretty big difference. 16 ounces is a 25% Penetrol cut, which is more than I've ever needed. 8 ounces is a 12.5% cut and about what I usually use. At 16 ounces, the Penetrol will affect the gloss (it'll dull a bit) and the drying time will go up a fair amount too.

    I'd recommend a 5% - 10% mineral spirits cut and 5% - 10% Penetrol, instead of a heavier Penetrol mix. Also, what temperatures are you applying it in? This type of paint likes it to be over the mid 70's to flow nice. If it's in the 60's, it'll just lay there.
     
  9. leaky
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    leaky Senior Member

    The rolling and tipping came out pretty good, has a nice shine to it. Likely it was closer to 8 ounces.. I'm an engineer, I don't just tend to measure things I tend to weight them :)..

    My buddy, who was involved because it's very clear I can't paint, did the mixing. Basically he just dumped some arbitrary amount of penatrol into a seperate 20 ounce mixing container and looking at it over his shoulder I took note that it was about 16 ounces..

    Then he proceeded to dump it into the paint, mix, and was observing how it flowed off a stir stick, dump some more, mixed, dumped some more, mixed. When done I noted what may have been as much as 8 ounces in the container still, which I put back into the penatrol can.

    Anyway - do you think that and/or the temp makes the paint bubble worse? And you think mineral spirits versus acetone? He had me pickup acetone but said we didn't need to use it after he saw the viscosity of the paint. It was a little colder at the time, like 60 degrees.

    Jon
     
  10. gonzo
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    gonzo Senior Member

    I use acetone when it is cold and humid. However, it gets less shine and more orange peel.
     
  11. PAR
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    PAR Yacht Designer/Builder

    Acetone is too fast and should be used with something else, like alcohol, spirits, toluene, etc. At 60 degrees this particular paint will be quite heavy and it's flow qualities will pretty much suck, even with a heavy cut and Penetrol. I'll bet a significant percentage of the bubbles was acetone flashing off, though the coating. As a rule, it just screws with most modified alkyds too much, so unless you have considerable experience altering paint chemistry, use more accommodating solvents and work in warmer temperatures, which can be a chore this time of year in your area.
     
  12. leaky
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    leaky Senior Member

    You misread that, I got the acetone but we never used it, so that isn't it, but as you state the temp was not 70 and it's absolutely tough in my area. Even in the tent where I can heat it up, you can't run the heat when painting because of the dust, so things are cooling off the second you shut it down.

    I'm gonna give it a shot w/ the urethane in the house - will test the straight-up mix and the penatrol mix as I've got a can of both now, see how it rolls at room temp. If that's the issue then it's pretty simple, I'll use the same paint for most everything on a 75 degree day.

    Jon
     
  13. gonzo
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    gonzo Senior Member

    Penetrol will retard the drying of the paint. Also, the specifications on the paint say "do not thin" several times.
     
  14. leaky
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    leaky Senior Member

    Ya I kinda wondered about that, it did not seem to, but maybe this paint flashes off really nice to begin with so the penatrol only makes it work like normal paint.

    I had asked my buddy the question about the penatrol because it seems like anything you add to it that doesn't evaporate real quick (and penatrol does not, stuff looks like motor oil!) is going to slow it down.

    Funny though - the P22 has no working temperature range listed on the can at all. I think it might say it dries slower in cooler temperatures but they don't even mention a ballpark.

    Jon
     

  15. gonzo
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    gonzo Senior Member

    This paint does not really flash off as much as cures by oxidation.
     
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