SVArcturus

Awlgrip paint, max time between coats

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I've finished all the prep and primer on my 36' Soverel and am ready to apply the topcoat (roll and tip).  I've done this several times before in decades past, but because I had a bunch of delays in the spring, this time I'm having to do it in the Florida summer heat and humidity.  Since Awlgrip advice for applying above 90F is to thin heavily (33%) and apply at least 3 coats instead of the normal 2.  

My plan is to apply two coats one after another with about two hours between and without sanding, then apply the third coat after a day or two and a light sanding.  Since afternoon rains are common (even though I have a sun cover over the boat it still has some places where water penetrates), I figure that at worst when I do the sanding the finish may already be flat from high humidity/water later on they day of application.  Not a problem.  However, I may have to wait for a while to get a reliable day for the final coat.

I don't find anything in the Awlgrip application documents that indicates a maximum time between coats.  Is it basically infinite Iwhich suggests that chemical bonding between layers isn't that important), or does one have to apply another coat of primer if too much time elapses?

There used to be a place to ask questions like this on the Awlgrip website, but I guess since Akzo Nobel bought them that isn't now an option!

May I close with the observation and advice that sanding and painting in temps above 90 with heat indexes over 100 (111 one day!) is HIGHLY undesirable and uncomfortable and a really bad idea.  If I didn't HAVE to complete it now, I'd wait until late fall for better conditions.

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Yep, and he was helpful.  thanks for pointing me that way.  For those that are interested in the answer, he basically said as long as the 3rd cure cycle isn't complete (about 2 weeks) then I"m good to apply the final coat (after light sanding).

I guess I think "sales" when I see sales rep, so didn't think them as a technical resource.  Seems like they could make that a bit more clear on their sparse "Support" webpage.  Of course, it doesn't mention Sales Rep on that page unless you look in the fine print at the bottom...

Thanks Fleetwood

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You're welcome. They're selling B2B, not the general public, so they (should) have to know their stuff. In a commodity business such as coatings, customer service can make all the difference.

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Awlgrip is a pain to apply, but I really like the longevity.  I want to paint as infrequently as I can.

I've used it for long enough (this is the fourth time I've applied it) to know that even in Florida I can count on 7 years of high gloss and "pretty good" until about 10 years, plus it is tough as nails once fully cured so doesn't ding easily.  Not much else comes close.

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Depends on temp and humidity, what you described just about guarantees solvent popping. Brushing reducer and catalyst slow it down to allow it to flow better. When spraying you can over coat almost immediately unless you're down at the bottom of the range. Usually I work in a 12 to 24 overcoat window, without sanding between coats but if it's  hot and humid then the window shrinks. If you just wait 12 hours and then scuff between each coat usually safe. Not sanding gives more texture but also more thickness. Scuff sanding between coats the opposite. For best adhesion follow the manual. In hot zones more thinning usually means 4 coats for full hide.

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??Wonder why the rep told me (and I quote) "Your plan for two hours between the first two coats is great and should be fine. With respect to the third coat, anything over 24 hours would require sanding or use of scotchbrite.  You do have up too two weeks for a fully cured system"

And yes, I had told him I was roll and tipping.

Guess I'll know soon.  Put two coats on the port side today, with about 3 or 3.5 hr between.  About 91F for the first coast and 85F for the second.  Crossed fingers.

Still trying to get a good handle on the thinning/rolling for these conditions.  Some sags on the first part of the first coast but also some areas later where it never glossed.  Think I as trying too hard to get a thin coat down (after seeing the sags develop on the early part).  One can go overboard.:o  The sags brushed out fairly well, and even glossed up again. Not bad after the second coat, but I'll need to do more than a scuff sanding.  Starting to get the hang of the right balance for these temps.  Should have that under control by the time I do the finish coat.  

Used to painting in 70s and low 80s. The paint handles much differently even at "only" 90 (and, of course, humid).  Hey  at leas the hurricane/tropical storm stayed a bit west of us...

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Thought I'd post an  final update.

Finally managed to finish all the finish coats.  Constant heat and routine rainy afternoons here in north Florida, plus a 10 day trip in the middle, made it take way longer than I'd hoped.  But it came out great.  

Like I'd mentioned before, after getting the primer coats on, we did two coats in one day on each side, with about 3 hours between them and temps basically around 90 or so.  Had some sagging on the first side we tried this that caused a lot of sanding before the finish coat.  The second side double-coat went much better, with few flaws and easy sanding before the final coat.  Practice makes perfect, or at least better.  Basically, we went back on the second side and brushed out some sags that developed below the rub rail (despite efforts to minimize the paint placed there) and a few below the deck edge.  We went back after doing half the hull then again at the end.  Even thought it was about 15-20 minutes before the sags were brushed (foam brush), the sag brushing flowed out entirely and was invisible.  We did that a bit on the first side, but were worried about the trade off between "late" sag removal and leaving rough brush strokes.  Should done more brushing.

Bruno had warned about the high probability of solvent popping under these conditions of high thinning (35%) and high temperature. We did get that, but frankly while I can see that is a real problem for those spray painting their Awlgrip, it wasn't a big deal when rolling/tipping.  After a few minutes some "bubbles" would appear in some areas of the paint ("solvent popping") but the "tipper" just tipped over it again and they disappeared.  No problem with subsequent reappearances.

All in all, don't paint Awlgrip in hot weather, but you can if you have to and still end up with a nice product.

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