Need grinder advice for smoothing deck boards before staining

Hey folks, I'm redoing my old pressure-treated deck and want to get it super smooth before applying new stain. The boards have some rough spots and minor cupping from weather. I've got a 4.5" angle grinder, but wondering if I should use a flap disc, sanding pad, or something else? Don't want to gouge the wood. Any tips from those who've done this?

Larry, for deck boards, skip the aggressive grinding. I'd use a 60-grit flap disc to knock down high spots, but go easy—you're not milling metal here! Then switch to a sanding pad with 80-grit for final smoothing. Watch for nails/screws; hitting one will ruin your disc. Also, wear a respirator—PT dust is nasty stuff.

RooferRob's on point. Seen too many DIYers go at decks with coarse discs and end up with wavy boards. If your grinder has variable speed, keep it low (like 6k RPM max). And check for raised screw heads first—I once inspected a deck where someone ground right into 'em, left shiny metal spots under the stain. Not a good look!

Thanks both! Variable speed tip is gold—mine does have that. I'll start with a 60-grit flap disc and keep it slow. Any brand recommendations for discs that last on wood? Last time I used a cheap one on a fence and it wore out fast.

Stick with name brands like Diablo or Norton for flap discs—they handle wood fibers better. And if you're doing a whole deck, get a few discs; they'll load up with pitch. Pro tip: use a stiff brush to clean the disc occasionally. Good luck, and post pics when it's done!