What's the frequency of the letter "o" in:
After spending several months of grinding, sanding and prepping my deck for paint, I finally got to spray topcoat (first time using Alexseal). The first coat went down beautifully, waited about 90 minutes and sprayed second coat... hundreds of tiny fisheyes immediately popped out! AHHH!!!
The boat is in a heated shop, about 65F and was cleaned and tacked meticulously before the first coat. Relatively certain there was no surface contamination especially since the first coat laid down so nicely. Also re-inspected the test panel that was used to check spray pattern and it also showed fisheyes on second test. The only difference in the 1st and 2nd coat, was that we added a small amount of Alexseal accelerator to the paint mix that we forgot to add initially.
Is it possible that the accelerator in the second coat (and not first) caused the problem? Could we have contaminated the mix during the addition? Or do we likely have air supply issues (we used a brand new hose)? Any other ideas? And what would be the best process to get rid of the fisheyes (wet sand or dry sand, what grit to start and end with)?
Since you don't know what the contamination was I'd wash it thoroughly with plain water, then soap & water then wipe with degreaser/solvent before sanding.
If you start with sanding you can grind the contaminant into the coating.
I had the same problem when I painted my boom - prepped it like a hundred other jobs then primed with zinc chromate. Everything was fine but when I top coated it with Trim Black it came out covered in fisheyes - it was like the boom had been waxed with silicone that floated to the top of the zinc chromate.
Re-prepping as above solved the problem - never did figure out what happened.
If there's a chance there's silicone or similar contamination you might need to blow an etch primer over before your next topcoat. A trick I've seen in a few boat shops.
I used a disposable medical syringe (without needle) to add the accelerator since it was only a few milliliters... I assumed it was sterile, but I am learning that sometimes the barrels are lubricated with silicone. I am thinking that I may have introduced the contaminate when adding the accelerator. I will definitely check the wrapper my next trip to the shop to ensure.
So I guess my next steps are cleaning/solvent washing the painted areas followed by wet sanding until smooth with 320 or 400?
Alcatraz are you saying the etch primer may be necessary even after aggressive cleaning and sanding smooth? or as a short cut to eliminate some steps? Thanks for the input.
Arrgh indeed. Got a filter/dryer on the air compressor too?
Yes there is a moisture separator/regulator on the compressor and also an inline dryer (desiccant) and inline water trap.
I'm thinking that the medical syringe introduced a contaminate, possibly silicone. I will work on the recovery tonight and hopefully get back to spraying later in the week.
I just got confirmation from the manufacturer that the medical syringe that I used to add the accelerator (in the 2nd coat) does, in fact, contain a silicone lubricant. I believe that I have my smoking gun. Hard to believe that a minuscule amount of silicone can screw up a whole batch of paint. Also learned from a coatings engineer that adding accelerator to the second (and not first coat) could have caused and issue with solvent entrapment... something about amine reaction and polymer chains...etc. etc.
So let my hard lesson be a warning to others - DON'T USE MEDICAL SYRINGES IN FINISH WORK!!!
So I have cleaned the painted section with comet, scothbrite and water and sanded smooth with 320 grit. I plan to continue the prep tonight and hope to reshoot tomorrow. I was originally planning 3 coats, but after seeing the coverage of 2 coats thinking maybe two. What is everyone doing with Alexseal (2 or 3)?
I use Awlgrip. I almost have it figured out. I have been using it for thirty years. Before that I used Interthane plus which I had also almost figured out. They simply didn’t have enough colors.
good luck with your brand.  I sat at lunch and made a list of things I used to do before I started spraying. I added 2315 accelerator to the entire mix... every layer. it came out pretty well.... and I immediately turned on all my heaters after I finished because the forecast said the temperature would drop from 80 to 50 in a couple hours and on own to 30 overnight.
The paint job was fingerprint proof by the time I left at 7 pm.

user
I counted 260 "o"s in that text.
assistant