Fastest way to sand fairing compound?

[HVAC86]

I made my own fairing compound from epoxy resin, colloidal silica and milled fibers, I had to fix several cracks and chips prepping a boat bottom. Now that I’ve got all the cracks and chips ground out and filled, I’m having the hardest time sanding this stuff. I literally sanded for an hour straight and basically have 2 small spots done. This is with a 4” palm sander and 60 grit paper. I then figured out I can hand sand this stuff faster, but is very labor intensive. I’m contemplating a variable speed belt sander but would be impossible to work around strakes and keep they’re shape. Any ideas?

[crank68]

Sounds like your compound is really hard....sounds like hand sanding may be the safest with that aggressive of a grit...

[CastingCall]

You likely didn't use enough filler vs. resin - the filler is what makes the fairing sand-able (wood flour works great for this, mixed to a peanut butter consistency). Lesson learned... always mix practice batches, let cure, and try sanding prior to committing to actual repair. I can empathize - had to grind away at rock-hard resin on REALLY large projects before, and it's NOT fun.

Try using an oscillating tool with a fairly aggressive grit grinding-rasp attachment to knock the hard filler down quickly. It's small enough to be super controllable. But it may get clogged up fast, so prepare to have several attachments available.

[marinetechnician]

Knock it down with 36 grit 5" disc and then skim it with 3M marine filler. Save a lot of headaches and also you will stand a better chance of getting it fair.