Currently doing:
320 dry, by machine
400 dry, by machine (rails, nose, tail by hand)
My question, when do you guys switch to by hand and wet.
600 dry or wet? Machine or hand?
I’m gonna just assume all are doing 800 and any higher wet and by hand.
Most of time i do mat finish so i stop at 240 dry on orbital, acryl spray around and light 320 scourer finish. When i must do gloss finish i start water at 320 then 400, 600, 800 then polish. It’s shine but too much work… I know pro guys that do all dry with orbital like car painter.
Hello; . Actually,from 600 grit you jump to 1000. Then in the “P” system sometimes you can have 800 but is not a real 800. P is a coarser system so 800 when exist is a real 600.
Second is that roto orbital that Lemat is referring sand smoother than the industry STD angle sander/polisher so when you finish with 240 actually you are finishing with the equivalent of a finer grit.
The first (but you can do the second grit too; depending on how many grits you would use) one is done dry due to SEE what s going on/wrong with the surface. Then switch to water due to the paper will bite more also to prevent a bit possible burn outs.
I know a lot of guys use it, but I think 320 is a waste of sandpaper. 220 (wer OR dry) 400 and then 600. If you still have scratches, hit it with white rubbing compound or “Perfect” scratch remover and then #2 Fiberglass Polish. Avoid the compound step if you can, just try to sand scratch free. I prefer to sand wet on my 400 and 600 grits. 1000 is for guys who can’t sand scratch free and don’t know how to use Compound.
I always use car painter rule: no more than 100 between dry grit, no more than 200 between wet grit. I polish near never, often “clean finish” with wet coarse scourrer on roto orbitale they say équivalent 320 grit. I use this scourer on cured epoxy to prep for next layer, work fine for this.
Lemat; when I mention that from 600 you jump to 1000 I meant that 1000 is the next grit after 600 in the STD grit system. If you use the “P” non STD system, that is coarser, actually you are changing numbers but using the equivalent grits.
Then is not the same if you gloss with gloss resin than if you gloss with hot coat resin than if you gloss with epoxy surfboard resin than if you gloss coat with multi pourpose epoxy resins.
Is not the same an average gloss polish than a high end mirror polish.
All that achieved with different techniques.
This is interesting stuff. I actually had no idea there are two standards for grading grits;
-The P scale, which is European. FEPA
-US Std, which United States. CAMI
Seems both are pretty equal at 220, but past 220 they begin to differ. And, as you point out, they drastically differ 400 and finer.
With that said, my schedule for gloss sanding is P320 dry, P400 dry, P600 wet, P800 wet. Then machine heavy cut compound, machine polish, hand wax. I do this for both poly gloss and RR epoxy gloss. Sound good or does poly vs epoxy need different schedules?
Reverb i use P grit scale. The P240 grit on my roto orbital + mat acryl spray hide well my bad finisher skills and give à décent finish product. When i have to polish i do it on hot coat polyester resin but i avoid it the best i can LOL.
Personally I like to use a machine for sanding up to 600 grit dry
I like to be able to see the scratches while I’m sanding
then I will hand sand the board to higher grits