Bona R540 Moisture Barrier/Primer is a one-component roll-on moisture membrane specially designed to mitigate vapor transmission on absorbent and non-absorbent subfloors. The polyurethane reactive primer is compatible with the entire Bona Adhesive System. KEY BENEFITS
• Mitigates potential moisture issues, like cupping, in new and existing construction
•Substitute for felt paper installed over plywood subfloors *

• Can be used as a sealer for plywood subfloors up to 20% MC
• Can be used for damp proofing concrete subfloors up to 95% RH & 18lbs**
• Dries fast allowing nail-down installation immediately
• No more tears in paper or seams to be concerned with - continuous film

* moisture readings up to 20%
** when applied as a two-coat system