DESCRIPTION
Primer L is a concentrated, solvent-free acrylic primer used before the installation of underlayment materials. It is green for easy identification. Primer L improves the bond between a properly prepared and profiled concrete substrate, and selfleveling underlayment. Primer L can also be used as a primer for gypsum-based underlayments and patches.

FEATURES AND BENEFITS
• Easy application and quick-drying
• Low odor and low VOCs
• Tinted green for easy coverage identification

INDUSTRY STANDARDS AND APPROVALS
LEED Points Contribution LEED Points
MR Credit 5, Regional Materials*..................................................Up to 2 points
IEQ Credit 4.2, Low-Emitting Materials –
Paints & Coatings......................................................................................1 point
* Using this product helps contribute to LEED certification of projects in the categories shown above. Points are awarded based on contributions of all project materials.

WHERE TO USE
• Use Primer L when applying a self-leveling underlayment on a properly prepared and profiled concrete surface.
• Use Primer L to prime the surface of poured gypsum underlayment materials and screeds/mortar beds.
• Use Primer L in between layers of MAPEI self-leveling underlayments.
• Interior residential (apartments, condominiums and homes)
• Interior commercial (office buildings, hotel rooms and hallways, restaurants and cafeterias)
• Interior heavy commercial (hotel lobbies, convention centers, airports, shopping malls, grocery stores and department stores) 
• Interior institutional (hospitals, schools, universities, libraries and government buildings)

LIMITATIONS
• Do not install over substrates containing asbestos.
• For moisture limits on this primer, refer to the moisture limits of the product to be applied over it.
• Use only when the ambient and substrate temperatures are between 50°F and 90°F (10°C and 32°C). For temperatures above 85°F (29°C), follow ACI hot-weather application guidelines. Allow at least 3 hours of drying before applying an underlayment (ACI 305-R10 and ACI 305-R90).
• In all cases, the surface temperature of the prepared concrete slab must be at least 5°F (2,8°C) above the dew point to avoid condensation on the concrete surface as Primer L dries.
• The maximum open time to recoat or to apply the underlayment or patch is 18 hours.
• Do not use on on-grade slabs that are subject to freeze/thaw cycles. 

SUITABLE SUBSTRATES
• Properly prepared, sound, dimensionally stable, fully cured concrete at least 28 days old with a tensile strength of at least 175 psi (1,21 MPa), as well as properly prepared and fully cured cement mortar beds and cement screeds
• Gypsum-based underlayments or patches that are dry, intact, well-bonded, stable and free of existing cracks Consult MAPEI’s Technical Services Department for installation recommendations regarding any substrates and conditions not listed.

SURFACE PREPARATION
• Thoroughly clean the surface of any substance that could interfere with the bond of the installation material, including dirt, paint, tar, asphalt, wax, oil, grease, latex compounds, sealers, curing compounds, form release agents, laitance, foreign substances and adhesive residue.
• Prepare concrete surfaces according to subfloor preparation requirements of the underlayment or patching compound to be applied.

MIXING
Note: Choose all appropriate safety equipment before use. Refer to the Safety Data Sheet for more information.
1. Dilute 1 part of Primer L with 3 parts of clean potable water. Do not use Primer L at full strength or any other dilution ratios.
2. Mix using a low-speed mixer and a Jiffy mixing paddle. Do not mix at high speeds, which may cause product foaming.

PRODUCT APPLICATION
Note: Read all installation instructions thoroughly before installation.
1. Pour the mixed primer onto the substrate and work it into the surface using a push broom or brush. Do not use a roller to apply. Do not puddle. Additional coats may be required upon visual inspection over extremely porous concrete.
2. Allow the material to dry for about 3 hours at 73°F (23°C) until it has turned into a green, transparent film (with no milky spots). Lower substrate temperatures and/ or higher humid conditions could extend the drying time.
3. The maximum open time between coats or before applying a leveler is 18 hours. Re-apply a second coat if the dried Primer L remains uncovered longer than 18 hours.

CLEANUP
• Clean equipment immediately with water. Mineral spirits may be used to remove primer that has dried on tools.

Product Performance Properties at 73°F (23°C) and 50% relative humidity
Laboratory Tests Results
Polymer type Acrylic Drying time: About 3 hours
VOCs : 34 g per L
Consistency:  Pourable liquid
Color:  Green
Temperature range for application:  50°F to 90°F (10°C to 32°C)

Shelf Life and Application Properties
Shelf life: 2 years when stored in original, unopened packaging in a dry, covered location at 73°F (23°C) and 50% relative humidity

CSI Division Classification
Cast Underlayment 03 54 00

Packaging Size 
Jug: 1 U.S. gal. (3,79 L) (2 jugs per case)
Pail: 5 U.S. gals. (18,9 L)

Approximate Coverage*
Size Coverage
1 U.S. gal. (3,79 L) diluted at a ratio of 3:1 (water to primer) 600 to 800 sq. ft. (55,7 to 74,3 m2)
5 U.S. gals. (18,9 L) diluted at a ratio of 3:1 (water to primer) 3,000 to 4,000 sq. ft. (279 to 372 m2)
* Coverage depends on the profile and porosity of the substrate.
Primer L ™

DATA SHEET DOWNLOADS

Primer L TDS

Primer L SDS