The boat in question is a red 1990 Donzi Z33 crossbow. The problem was HEAVY oxidation and years of neglect. The solution was to sand and polish it back into shape. Now this gel coat was REALLY bad, the raised edge from the full length hull decals needed to be removed so the entire hull was sanded with 320 on a DA, then 600, then, 1000 wet, followed by 2000 wet. Those steps seemed to go without a hitch aside from then random deep scratches which seem unavoidable when wet sanding with thosethose super fine grits.
Next was to move onto compounding. I used a variable speed rotary, with a makita wool pad and 3M super duty compound. Yes, this compound may be a little rough, but I wanted to make sure and get the random deep sanding scratches picked up from wet sanding with a DA. This is where things hit a wall though.
While the surface does looks a lot better than before, and is fairly reflective, it just isnt what it should be. The surface is retaining a roughness average that I can't get rid of resulting in dull reflections. While the reflection may look 'ok', when up close and looking at the a reflection of a straight line...and then focusing on the surface of the boat is when it shows best...very uneven.
If were asked about this problem I would say it wasn't sanded enough with the finer papers before moving to compound or the pad was the problem. But even sanding a small section by hand with the two smoothest papers and then compounding yielded the same result, as did skipping the compound and going straight to the 3M machine polish..with a foam or wool pad. Light pressure, heavy pressure, low speed only, low speed increasing to high with less pressure...always the same roughness average making go insane.
Looking closely at the surface its almost as if the pigment in the gelcoat is polishing off at a different rate than the gelcoat resin? Could it be this gel coat is too far gone to be saved? Could the compounds be the problem? Should I continue wetsanding with 3000 grit trizact discs or up to 4000 Abralon discs and use a gentle polish on the DA from there? This is a pretty big boat, and I can't afford to spend another 40 hours on this hull on top of the 50 or so I've already got in it.
So any help would greatly appreciated.
Next was to move onto compounding. I used a variable speed rotary, with a makita wool pad and 3M super duty compound. Yes, this compound may be a little rough, but I wanted to make sure and get the random deep sanding scratches picked up from wet sanding with a DA. This is where things hit a wall though.
While the surface does looks a lot better than before, and is fairly reflective, it just isnt what it should be. The surface is retaining a roughness average that I can't get rid of resulting in dull reflections. While the reflection may look 'ok', when up close and looking at the a reflection of a straight line...and then focusing on the surface of the boat is when it shows best...very uneven.
If were asked about this problem I would say it wasn't sanded enough with the finer papers before moving to compound or the pad was the problem. But even sanding a small section by hand with the two smoothest papers and then compounding yielded the same result, as did skipping the compound and going straight to the 3M machine polish..with a foam or wool pad. Light pressure, heavy pressure, low speed only, low speed increasing to high with less pressure...always the same roughness average making go insane.
Looking closely at the surface its almost as if the pigment in the gelcoat is polishing off at a different rate than the gelcoat resin? Could it be this gel coat is too far gone to be saved? Could the compounds be the problem? Should I continue wetsanding with 3000 grit trizact discs or up to 4000 Abralon discs and use a gentle polish on the DA from there? This is a pretty big boat, and I can't afford to spend another 40 hours on this hull on top of the 50 or so I've already got in it.
So any help would greatly appreciated.
