John Blazy
07-22-2016, 11:01 AM
Ive been finishing with two part automotive urethanes for several years on small projects, and recently discovered a few cool tricks. I prefer 2 part urethanes because they are cheap ($65.00 per gallon) and extremely durable, easy to buff to high gloss if wanted. Sprayed directly over wood, it shows the woodgrain nicely, and sprayed over epoxy (like my boat below) creates a filled base that allows buffing to be like glass.
So I refinished my boat last year because my neighbor gave me some high-end 2K MARINE urethane (Bristol), which I always wanted to use, but didnt since its over 200 per gallon (same as the cheap stuff, but with UV blockers and HALS, which are pricey - I used to be a 100% solids coating chemist, and those UV additives (CIBA Geigy Tinuvin line) are super pricey).
So a couple weeks after application when the finish was hard enough, I lanced off a few dust nibs, runs and sags, and just locally wet sanded and buffed using my favorite system - razor scraping, 1000 grit paper, then rubbing compound followed by machine glaze (swirl mark remover) - only hitting the blemishes, not the entire surface, because it frankly leveled out pretty nicely - very little orange peel.
Fast forward over a year later to last week when my motor died and my axle broke, and the boats now available for a real rub-out. The front foredeck is nice, but there is wavy orange peel - hardly discernable, but I knew what it COULD look like.
So I made a flat long block to sand the high spots (now that I think about it, I should have scraped it first with a 6" long glass scraper blade to hit ONLY the high spots) and used 600 grit wet.
Heres the first trick - after the 600 grit, I mounted a 1000 grit trizact onto my variable speed grinder, then followed with a 3000 grit 3M Trizact disc that I had, and they removed the 600 grit scratches so well that the rubbing compound came to glass-flat gloss quite fast. - I highly recommend these discs.
Then the bad move: NEVER use a lambs wool bonnet. No matter how clean and virgin the pad, it flattens to a hard pack that balls up the slurry into tiny balls that scratch into this glorious finish like 80 grit. So I switched to a foam pad instead - unreal. No scratches at all. Then followed with 3M Perfect-It machine glaze. Most people stop at fine cut rubbing compound (MacGuires or 3M - all good), as the gloss is insane, but if you want it to look WET, then finish with machine glaze on SEPARATE foam pad.
First pic is before flattening / rubbing out, next two are after. The color balance is off on the first pic, but it shows waviness in the reflections from the orange peel that needed flattening.
341164341165341166
So I refinished my boat last year because my neighbor gave me some high-end 2K MARINE urethane (Bristol), which I always wanted to use, but didnt since its over 200 per gallon (same as the cheap stuff, but with UV blockers and HALS, which are pricey - I used to be a 100% solids coating chemist, and those UV additives (CIBA Geigy Tinuvin line) are super pricey).
So a couple weeks after application when the finish was hard enough, I lanced off a few dust nibs, runs and sags, and just locally wet sanded and buffed using my favorite system - razor scraping, 1000 grit paper, then rubbing compound followed by machine glaze (swirl mark remover) - only hitting the blemishes, not the entire surface, because it frankly leveled out pretty nicely - very little orange peel.
Fast forward over a year later to last week when my motor died and my axle broke, and the boats now available for a real rub-out. The front foredeck is nice, but there is wavy orange peel - hardly discernable, but I knew what it COULD look like.
So I made a flat long block to sand the high spots (now that I think about it, I should have scraped it first with a 6" long glass scraper blade to hit ONLY the high spots) and used 600 grit wet.
Heres the first trick - after the 600 grit, I mounted a 1000 grit trizact onto my variable speed grinder, then followed with a 3000 grit 3M Trizact disc that I had, and they removed the 600 grit scratches so well that the rubbing compound came to glass-flat gloss quite fast. - I highly recommend these discs.
Then the bad move: NEVER use a lambs wool bonnet. No matter how clean and virgin the pad, it flattens to a hard pack that balls up the slurry into tiny balls that scratch into this glorious finish like 80 grit. So I switched to a foam pad instead - unreal. No scratches at all. Then followed with 3M Perfect-It machine glaze. Most people stop at fine cut rubbing compound (MacGuires or 3M - all good), as the gloss is insane, but if you want it to look WET, then finish with machine glaze on SEPARATE foam pad.
First pic is before flattening / rubbing out, next two are after. The color balance is off on the first pic, but it shows waviness in the reflections from the orange peel that needed flattening.
341164341165341166