Thanks for the reply Johnny.
Here's some background:
I'm about 50 miles west of Chicago. The weather has not been all too bad for us, we've had some high temps the last few days, but the rains from earlier in the summer dried up in the last few weeks and we've had what I'll call typical Chicago August humidity for last week with decent winds so it been somewhat comfortable without needing to fire up the AC. (At least comfortable for me without the AC.) It's nothing like the hot and humid in the South where I'm reading success stories with Duralux.
This is a '91 Lowe 14' Delta John. The previous paint was not too bad to start with. The hull bottom was pretty well scratch up and sanding smooth did get some of it to bare metal. There we a lot of stickers on the hull sides so I used stripper to get those and all the glue off before hitting these areas completely with a stainless cup brush. This took these areas down to bare metal. I then pad and hand sanded the entire boat at 80-120 grit, exposing more bare metal as well. All places where the OEM coating was still in tack were exceptionally solid.
I've done plenty of fiberglass and wood boats before, not aluminum. I've read just about every post here as well as several other forums on painting these jon boats, and I got pretty comfortable with the Duralux product. I figured that since I heard all the talk on not needing primer I'd give it a shot. Since I could get it though Home Depot I went that way, with 'ship to store' saving me the cost of shipping direct. I like the M691 Duck Boat Drab color over the other Duralux greens and decided to go with that one at $34 a gallon rather than the M736 Aluminum Boat Green or others at $75/gal. I figured they were the same formulation, just a different shade and that Home Depot was just jacking up the price for the Aluminum Boat Green as more people bought it.
When the M691 arrived I was disappointed to read the label calling for use of M739 Duralux Zinc Chromate Like Primer on any bare spots and figured there might be a formula difference. I don't know this for sure though. If anyone out there reading this has a can of M736 Aluminum Boat Green around, could they please check the label and advise if it calls for priming with M739 on bare spots?? I went ahead and ordered the M739 through Do It Best and got on with it when it arrived. ($15/qt and another $15 for shipping.)
I scrubbed well using Zep Purple de-greaser and rinsed, rinsed, rinsed, and blew dry. I etched for about 30 minutes keeping a mix of 50/50 white vinegar/water wet, then rinsed, rinsed and rinsed again, blowing dry.
I've been spraying in the evenings when the temps and humidity die down. Again, around Chicago we don't see nearly what the guys in the South do... The Zinc Like primer shot on very well with a 1.5 tip at about 35 lbs and I was actually impressed with it. I dusted with it as recommended, second shooting a little more where the bare metal was after I finished the first dusting over the whole outer hull.
I have a plastic spray booth set up in the garage and the fan is in the window to blow out, circulating air and exhaust. I don't think a $200 60 pt. basement dehumidifier will do much for this garage space and I'm not spending on anything more just to paint this boat. It is hot in there and I know the humidity does come into play. Call it about 100 degrees at 80% humidity, peak.
After letting the primer sit for about 24 hours I sprayed the first layer of M691. The manufacturer's label does not recommend thinning, but if you desire they recommend no more than 16:1 their own thinner or Xylene. I went ahead and did not thin as that is the initial recommendation. I found it rather thick to shoot with the 1.5 tip. It was difficult to get and even spray, seeming 'spurty'. They recommend two full coats, so I shot these 24 hours apart. It has sat in the garage for the last two days and that's were I was when I posted this morning....
What I found this morning is that I could easily scratch the drab color away revealing a whitish/gray color with my fingernail. The surface was not smooth, rather somewhat 'spurty' textured. This was the case everywhere on the hull, not just where stickers may have been, bare metal or the OEM's coating was, or even on the new aluminum diamond plate I installed -wire brushed, washed and etched prior to painting.
A few passes with 80 grit and the color was gone, revealing a hard white/grayish surface. The dust would chalk up, not gum, and I'd have to slap the paper often. I hand sanded at 80 and followed up with a medium sanding sponge to get the whole surface to this grayish hard surface. If I sanded too much I could get to the yellow layer which is the Zinc Like primer. The rivet heads obviously took the brunt of the sanding and are now exposed as bare. Rinsing with water revealed the color M691 should provide as present when wet, when dry it reverts to the grayish/green chalky color. The surface is hard and I cannot scratch it with my fingernail any further....
I think in trying to get to the 'two full coats' I may have sprayed too much on. I used half a gallon in the two coats un-thinned and think that for the temp/humidity it may have been too thick.
As I still have half a gallon of M691 left what I think I'm going to do is thin it at 16:1 Xylene and see if it sprays any smoother. If not, thin more till it does.
I think I need to wash again as there's quite a bit of dust about.
I think I'll get a spray can of Rust-Oleum self-etching primer and re-prime the rivets and other places where this morning's sanding exposed bare metal again and let it dry till tomorrow.
Then tomorrow evening shoot a thin coat of the thinned M691 to see it revives the color over the whole hull.
If so, shoot the rest of the hull exterior with thinned M691, trying to use up the half gallon in three more spray coats 24 hours apart. I think I'll move the boat out of the garage into the sun in the morning as well to let it bake in the sun through the day too.
Any other ideas/advice I'd like to hear.
Thanks Again....