"I’m hoping that Dennis will chime in …” Well, that was quick!
I should have mentioned that the work done to my boat was done to the original gelcoat. But three coats seems to just be good practice, no matter what. And I had to laugh at the Hutchins pneumatic sander. I spent many hours in my youth with one of those. I think it is still somewhere collecting dust in my shed. Best, Dave Godwin 1982 C&C 37 - Ronin Reedville - Chesapeake Bay Ronin’s Overdue Refit <http://roninrebuild.blogspot.com/> > On Mar 29, 2016, at 8:20 AM, Dennis C. via CnC-List <cnc-list@cnc-list.com> > wrote: > > Russ, > > Long answer to your question but it shows what can happen with painting an > old boat. It also illustrates that preparation is 80% of most jobs. Kinda > of a primer on primers. :) > > I'm not sure if the contractor long boarded between or after primer coats. I > wasn't there when the contractor did that portion. However, there was more to > it than just removing 40 years of scratches and dings. > > First, some history. A close examination of the existing paint showed > numerous "fish eyes". Tiny pinprick size holes in the paint where it > apparently didn't completely lay down. I had heard "dock tales" about how a > PO had hired the local boat yard's painter to paint the boat in the water > over a weekend. Rumor was they tied it side to at a bulkhead, set an anchor > a ways out and careened it slightly with a masthead halyard. The guy painted > it from a dinghy. The next day they swapped it and painted the other side. > The rumor was they used Imron paint. > > This dubious story led the painting contractor and I to question everything > about the paint job. On his advice, I scrubbed a 3 x 3 foot section of the > hull, repaired some dings and sanded it with 320 grit. He was painting a > nearby boat with white AwlCraft. At the end of that job, he came over with > the paint gun and sprayed the test area. > > What??? The paint beaded up in spots. Where I had done the repair exposing > underlying coats of paint, it reacted with those other paints. Some layers > peeled up slightly and other layers reacted turning the white AwlCraft pink. > Upon seeing this, we decided we needed to sand the entire topsides to remove > all the layers of unknown paints. > > When working with $250/gallon paint and the risk of a botched job, we decided > removing the old paints was the safest course of action. > > I did most of the smoothing myself with a Hutchins straight line sander like > this: > > http://www.hutchinsmfg.com/View-Product.aspx?group_id=424043 > <http://www.hutchinsmfg.com/View-Product.aspx?group_id=424043> > > If you use a disc sander, you risk creating gouges or divots in the hull. > Especially if using a smaller sander like a 4 or 5 inch diameter. When > applying a high gloss paint, it is critical that you have a very smooth > surface. > > The straight line sander is held horizontally and moved up and down the hull > at a slight angle to vertical. That is, in a "V" pattern. > > If you got up close and personal with Touche's topsides prior to the > painting, you would have noticed a lot of imperfections. Much was due to > post cure shrinkage. I could see the pattern of the underlying roving as > well as the vertical "dimple" at the upper shroud brace. The sander removed > nearly all the imperfections. > > As I sanded, I definitely saw several layers of old paint. I even found the > original name "Touche" in the gap in the cove stripe under the shrouds. It > was under at least 2 layers. > > Even though I removed as much of the old paint as I could, there were still > small spots in recessions in the hull. When the contractor shot the primer, > he saw small spots where the primer reacted with the old paint. Additional > coats where required to "bury" the old paints. > > So, to answer the question of why 3 coats of primer, it was both for > smoothing physical imperfections as well as for "burying" spots of the old > paint. > > Dennis C. > Touche' 35-1 #83 > Mandeville, LA > > > On Mon, Mar 28, 2016 at 11:08 PM, Russ & Melody via CnC-List > <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote: > > Hi Dennis, > > Was the 3 coats of high build primer for long boarding to a fair hull? > > When I did the decks I was set to do high build primer and the paint rep > suggested going the regularly spec'd (2 pot) primer. > > I have a hull paint project coming up next year and the hull needs fairing, > so I'm looking for best practices. > > Cheers, Russ > Sweet 35 mk-1 > > At 09:00 AM 28/03/2016, you wrote: >> My only substantive comment on paint is to consider Awlcraft vs Awlgrip. >> Particularly true if you're concerned about scratches. Awlcraft is easier >> to repair and blend. >> >> Touche' is Sunfast Red Awlcraft over 3 coats of high build primer. The >> Awlcraft looks great! >> >> Dennis C. > > _______________________________________________ > > This list is supported by the generous donations of our members. 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