Why does my deck look patchy after I have applied Decking Stain?

This is more common with water-based products as they tend dry much faster and if applied incorrectly you will get overlapping patchy marks across the deck surface expanse. It’s usually due to applicator lap marks which you can fix, but you need to leave it for at least 7 days for the coating to harden up then lightly sand the lap marks out and recoat the deck. When coating large areas, work in sections, apply long strokes and use natural breaks in the boards as stopping points.