PSI-591 Primer for Porous Surfaces Product description PSI-591 Primer is a reactive polyurethane which promotes the adhesion of PSI polysulfide and polyurethane sealants primarily to porous substrates such as concrete. It reacts with atmospheric moisture to form a hard film with outstanding water resistance and high adhesive strength to many materials. Basic uses PSI-591 Primer should be used when a single-component primer is needed on porous materials such as when firming up friable or sandy concrete, or on brick and stone. It also provides water resistance when PSI urethane sealants are used on non-porous materials such as metals and plastics. However, PSI-590 non-staining primer is the first choice for these materials. For PSI urethane sealants in joints subjected to continuous water immersion, PSI Primer #67, a two-part epoxy-based material, is recommended. Application limitations • If sealant cannot be installed within 24 hours, reprime. • Avoid smearing primer on exposed surfaces as it yellows on exposure to sunlight. • Do not apply over wet or damp substrates. • Do not apply primer to backer rod to prevent three-sided adhesion. Application: Apply primer by brush, roller, or spray in a thin continuous film. Avoid pools, runs and drips. Allow primer to become dry to the touch before installing sealant. Primer reacts with moisture; keep container tightly closed when not in use. Clean Up: Equipment can be cleaned immediately after use with xylol, mineral spirits or isopropyl alcohol. When using flammable solvents, consult manufacturer's MSDS for safety precautions. Shelf life: One year from date of shipment when stored in original, unopened container at temperatures between 40 and 80°F (4 to 27°C). Technical services PSI provides field service, performance data, specification assistance and use evaluations. Adhesion testing by PSI: This program is intended to eliminate potential field application problems by pre-testing the adhesion of PSI's construction sealants on samples of building materials submitted by the customer. The tests will aid in determining the proper surface preparation method, effective solvents for cleaning and whether priming is necessary to achieve optimum adhesion. Following this procedure will remove many of the variables that affect field success. Application Properties* Consistency Amber colored liquid Specific gravity 0.8 Density 6.7 lb/gal Available in quart (946 ml) cans. Dry time from priming to sealant Application application, dependent on ambient Preparation:The surfaces to which temperature and relative humidity 30 minutes to primer is applied must be clean, dry 2 hours and free of laitance, loose aggregate, Open time 24 hours oil, grease, wax, mastic compounds, VOC content 6.5 lb/gal waterproofing compounds, corrosion, Flash point 104°F (40°C) rust and previously-applied sealants. * Typical properties are for information only, not for purposes of specification. Packaging

Test samples should be identified as to manufacturer, origin, designed use, building project, person and firm originating the request. Appropriate sketches of drawings showing the intended use can be helpful. They should be sent to the attention of PSI's Technical Director. Jobsite testing of substrates: A field test can be performed by applying several feet of the sealant to a representative joint and letting it reach full cure. Make a cut in the cured sealant across the joint the entire depth of the sealant. Make two vertical cuts several inches long, paralleling the sides of the joint as closely...