Pin holes (again)

I just spot sprayed 3 areas with Concept AU after modifying the root rib area IAW the Salve modification to the Genesis-2. I let the paint cure for 2 days, because parts were sticking out of the shop and I couldn't close the doors to heat the shop (70 day/40 nite). Today I wet sanded it out with 600, then buffed the new paint out with liquid buffing compound (with water) and a wool buffing pad. The 600 scratch marks are completely gone and the paint has a high luster with only one buffing. However, the sanding scratches in the old paint (in the blend area) are quite visible and I was forced to remove them with traditional methods, 800, 1000 then several buffing passes with increased pressure and adding water to the buffing compound to increase the cutting action on the old hard paint.
So, what does this mean? Countless hours can be saved on a complete re-finish job by sanding the paint out while it is quite new and green enough that the 600 scratch marks are completely removed by the cutting action of the buffing pad and compound + water.
JJ

JJ, perhaps the polishing compound that you are using is key. Can you share what you are using?

On Thursday, May 11, 2017 at 7:01:41 PM UTC-4, wrote:
I just spot sprayed 3 areas with Concept AU after modifying the root rib area IAW the Salve modification to the Genesis-2. I let the paint cure for 2 days, because parts were sticking out of the shop and I couldn't close the doors to heat the shop (70 day/40 nite). Today I wet sanded it out with 600, then buffed the new paint out with liquid buffing compound (with water) and a wool buffing pad. The 600 scratch marks are completely gone and the paint has a high luster with only one buffing. However, the sanding scratches in the old paint (in the blend area) are quite visible and I was forced to remove them with traditional methods, 800, 1000 then several buffing passes with increased pressure and adding water to the buffing compound to increase the cutting action on the old hard paint.
So, what does this mean? Countless hours can be saved on a complete re-finish job by sanding the paint out while it is quite new and green enough that the 600 scratch marks are completely removed by the cutting action of the buffing pad and compound + water.
JJ

i'd be curious to see the finished piece, i don't like the idea of "burnishing" soft paint (IE moving paint material to fill scratches.) i just feel like i could get it much smoother by hand. also, I begin PU with 800, and after doing a similar amount of sanding to what you are doing with 600, there really not much more sanding after that. you do have to step through 1000 then 1500 doing it my way, but its pretty quick. it's certainly not hours and hours, especially not for something small like the wingroot mod on a genesis. in any case, i love the luster and finish quality of gelcoat, but i much prefer working with PU. it's much less sanding!

I usually start with 800, but accidentally got a quarter sheet of 600 mixed up with 800 and was surprised to see the big scratches in the old paint in the blend area. But this showed me that the new paint that had been sanded with 600 showed no scratch marks after buffing. I have seen two ways to buff out sanded paint, the "dry" method picks up a bit of compound and buffs out a small area. I was shown the "wet" method by an old car painter where I squeeze out a ribbon of compound about 3 feet long, then dip 2 square inch rag in water, squeeze it a bit and then spread out the ribbon to make the area about a foot deep X 3 feet long. Starting with a 4" bite, I make repeated passes left to right starting with increased pressure, the backing off the pressure until I not have only the weight of the buffer pressing down as the luster shows through. More cutting in obtained by increasing pressure and/or, by using more water. I use 3M rubbing compound. E-mail me at johnsinclair210(at) yahoo.com and I'll be glad to send you photos of a couple ships finished by sanding out Concept Acrylic Urethane while the paint was quite new.
JJ