121 Asphalt Primer

121 Asphalt Primer

121 Asphalt Primer

A general-purpose penetrating asphalt primer used to promote adhesion prior to the application of hot-mopped, cold-applied and self-adhesive membrane systems, as well as roof cements, mastics and asphalt-based adhesives.

  • ModBit
  • M&R

Features & Benefits

  • Designed to be used on smooth surfaced built-up roofs, polymer-modified (APP, SBS) bituminous membranes, and roll-roofing membranes as a protective coating
  • DO NOT USE with PVC, TPO, EPDM or other single-ply membranes
  • Can be used as a protective surface for metal roofing, masonry, stucco, parapet walls, curbs and base flashings
  • Meets  Miami-Dade-County Standards
  • Meets  ICC-ES Standards




Item ID Description Packaging Qty per Ctn Weight per Ctn Cover Rate
16MH12114 MH 121 ASPHALT SPRAY PRIMER 14 oz 30/CT Spray Can 30 37 30 sq. ft. per can
16MH1215 MH 121 ASPHALT PRIMER 5 GAL Metal Pail 1 41 1 gallon per 100 sq. ft.
16MH12150 MH 121 ASPHALT PRIMER 50 GAL Drum 1 408


Application Example Image
Application Example Image
Application Example Image


Mule-Hide #121 is a solvent-based bond coat and penetrating sealer for priming most surfaces prior to application of cold applied or hot mopped asphalt coatings, roof cements, adhesives, asphalt damp proofing and waterproofing. Not recommended as a stand-alone roof coating.
Application range is between 0.5-1.0 gallons per 100 sq. ft. depending on surface porosity.
Apply a thin, single coat of#104 over the entire surface with a roller or heavy-duty spray equipment. Brush out any excess immediately after application. Avoid over-application and build-up of surface film. Allow to dry thoroughly before applying adhesives or coatings. Store primer in a warm room overnight before using in cold weather.
#121 Asphalt Primer dries in approximately 2-24 hours in warm, dry weather. Drying time varies with weather conditions.
No, DO NOT use #121 Asphalt Primer on PVC, TPO, EPDM or other single-ply membranes.
With proper storage, the shelf life of Mule-Hide #121 Asphalt Primer is 24 months from the date of manufacture, for bucket goods. Aerosol cans may leak propellant over time, leading to a shortened shelf life of only 12 months. Store primer in a warm room overnight before using in cold weather.
#121 Asphalt Primer should be stored at a temperature of at least 45°F but not above 120°F. It should be stored at room temperature for at least 24 hours prior to use.
#121 Asphalt Primer should only be applied when the ambient temperature is at least 45°F and rising. Cold weather can result in uneven application and improper curing, and it will cause the product to stiffen, making application more difficult. Application is not recommended if the substrate temperature is above 140°F.