GSL® ALL PURPOSE SEALER (APS) is recommended for use on all GSL® (family of products) installed systems to enhance the bond of underlayment to finished floor covering.

GSL® ALL PURPOSE SEALER applied to surface of gypsum underlayment will eliminate any dusting creating a durable surface resistant to incidental moisture, resulting in an ideal surface for most floor coverings. One coat is all that is required, just mix at a 1 to 3 ratio with water and apply using approved methods.

Features and Benefits

  • Meets ASTM F2419
  • Zero VOC
  • Resists water & bleed through
  • Mildewcide protection
  • Simple 1 to 3 mix ratio
  • Outstanding flexural strength

  • 5 gallon pail with easy pull lid
    •    approx. 5,400-6,400 sq. ft. coverage (prepared solution)
  • 55 gallon drum
    •    approx. 60,000-70,000 sq. ft. coverage (prepared solution)

270 – 320 sq. ft./prepared gallon

Dilution: 1:3 with potable water

Approved Substrates:

    GSL® K2.6

    GSL® M3.4

    GSL® CSD

    GSL® RH

    Most gypsum based self-leveling underlayments (Consult Dependable LLC Technical Department)

Surface Preparation:

Prepare surface according to applied underlayment instructions. Ensure underlayment is fully dry and clear of any contaminates, including but not limited to: oil, dirt, wax, paint, etc. The floor may be wiped with a wet rag to reduce surface dusting. Ensure substrate is structurally sound and free of any mechanical defects.

Recommendation for final floor covering and floor covering adhesive supersedes preparation guidelines for GSL APS, as GSL APS is not an approved moisture barrier.


Mix GSL APS with potable water at a 1 to 3 ratio (GSL APS to water). Stir gently ensuring the product is mixed well. Do not stir at high speeds or overmix (to prevent air bubbles). Remix prepared solution every ten minutes to ensure homogenous product.


Ensure application sites are enclosed and not subjected to temperatures below 50°F or above 90°F. GSL APS can be applied with sprayer, medium nap roller, soft bristle broom or any combination thereof. Work GSL APS into surface of underlayment; additional coats may be required upon visual inspection of extremely porous substrates. Do not allow GSL APS to puddle. Allow GSL APS to dry completely (temperature dependent, approx. 2 hours). Apply final floor covering within 18 hours of GSL APS application. If 18 hours is exceeded, apply additional coat of GSL APS.


GSL APS can be immediately cleaned with soap and water. Mineral spirits may be used to remove GSL APS that has been allowed to dry.


  •  Keep product from freezing

  •  Store between 40°F and 90°F

  •  Not approved as a wear surface, for interior use only

  •  Shelf Life: 12 months from manufacture date