Because without a properly prepared surface, even the best product will deliver disappointing results. Construction lumber is usually planed, which closes the wood fibers and prevents good penetration.

Sanding with 60–80 grit is therefore essential, whether it’s for a new deck (after at least 6 weeks) or for old wood cleaned with Prato-Verde’s Cleaner & Brightener. Sanding reopens the wood fibers and allows for optimal absorption. Rough-sawn, unplaned wood does not need sanding.

Penetrating finishes are designed to soak into the wood without forming a film, thus eliminating the risk of peeling — but only if the surface is properly prepared. Sanding too finely (120 grit) or applying in full sun can prevent penetration, which inevitably leads to peeling or poor adhesion.