Concrete block is porous and pitted, so it gets a heavy block filler or a masonry primer before paint, and only after it has cured and dried. Benjamin Moore's block filler, for example, covers just 75 to 100 square feet per gallon and is not recommended below grade.
Block has open pores and voids that paint alone would sink into or bridge poorly. Benjamin Moore describes its Ultra Spec Hi-Build Masonry Block Filler as a full-bodied latex that fills small cracks and voids in concrete, cinder block and rough masonry to create a less porous, smoother painting surface. It is applied heavily: 75 to 100 square feet per gallon at a dry film of 8.5 to 11.3 mils.
Benjamin Moore's data sheet says the block filler should not be used as a waterproofing sealer or as a finish coat, is not recommended for below-grade applications, and should not be applied when surface or air temperature is below 50°F. Basement walls below grade therefore need a different product choice, and moisture problems have to be solved before any coating.
No. Benjamin Moore's Aura exterior data sheet says new masonry substrates must cure for 30 days before painting, and that surfaces with a pH of 10 or more should be primed with its Ultra Spec Masonry 100% Acrylic Sealer or High Build Masonry Primer. Fresh concrete and mortar are highly alkaline, which can damage paint.
All three are listed with a 50°F minimum application temperature.
Exterior block takes an exterior acrylic; Benjamin Moore lists Aura exterior for cured or previously painted masonry including cement block, and an elastomeric such as its Ultra Spec Masonry Elastomeric Waterproofing Coating for exterior block where a thick, flexible film that bridges minor imperfections is wanted. Interior block walls take a durable interior finish.
A 40 foot long, 8 foot high block wall is 320 square feet. One coat of block filler at 75 to 100 square feet per gallon is roughly 3.2 to 4.3 gallons, before two finish coats at the paint's normal spread rate. That ratio is why block projects use far more material than drywall of the same size.
Benjamin Moore lists its elastomeric masonry coating as washable after two weeks and its masonry sealer and block filler with 4 hour and 2 to 3 hour recoat times. Painted block in commercial and garage settings often gets cleaned often, so allowing full cure before scrubbing protects the finish.
Joseph Assise III Painting is based in Easton and serves towns across eastern Pennsylvania and western New Jersey, centered on the Lehigh Valley. Town pages:
Allentown, PA | Asbury, NJ | Bangor, PA | Bath, PA | Belvidere, NJ | Bethlehem, PA | Blairstown, NJ | Bloomsbury, NJ | Breinigsville, PA | Brodheadsville, PA | Budd Lake, NJ | Califon, NJ | Catasauqua, PA | Center Valley, PA | Chester, NJ | Clinton, NJ | Columbia, NJ | Coopersburg, PA | Coplay, PA | Danielsville, PA | Delaware Water Gap, PA | Doylestown, PA | East Stroudsburg, PA | Easton, PA | Effort, PA | Emmaus, PA | Flanders, NJ | Flemington, NJ | Fogelsville, PA | Forks Township, PA | Fountain Hill, PA | Frenchtown, NJ | Germansville, PA | Glen Gardner, NJ | Great Meadows, NJ | Hackettstown, NJ | Hampton, NJ | Hatfield, PA | Hellertown, PA | High Bridge, NJ | Hope, NJ | Jim Thorpe, PA | Kresgeville, PA | Kutztown, PA | Lehighton, PA | Long Valley, NJ | Macungie, PA | Martins Creek, PA | Mendham, NJ | Milford, NJ | Mount Olive, NJ | Mount Pocono, PA | Nazareth, PA | Netcong, NJ | New Hope, PA | New Tripoli, PA | Northampton, PA | Oxford, NJ | Palmer Township, PA | Palmerton, PA | Pen Argyl, PA | Perkasie, PA | Phillipsburg, NJ | Portland, PA | Quakertown, PA | Raubsville, PA | Riegelsville, PA | Roseto, PA | Saylorsburg, PA | Sellersville, PA | Slatedale, PA | Slatington, PA | Souderton, PA | Springtown, PA | Stanhope, NJ | Stewartsville, NJ | Stockertown, PA | Stroudsburg, PA | Tatamy, PA | Topton, PA | Trexlertown, PA | Upper Black Eddy, PA | Upper Mount Bethel, PA | Walnutport, PA | Washington, NJ | Wescosville, PA | Whitehall, PA | Williams Township, PA | Wind Gap, PA
Local guides with housing-age and climate data: Lafayette College, Easton | St. Luke's Easton Campus | Lehigh University, Bethlehem | SteelStacks, Bethlehem | Wind Creek, Bethlehem | Lehigh Valley Hospital, Cedar Crest | Dorney Park, South Whitehall.
Yes, with the right masonry product. Rough block gets a block filler that fills pores and voids; smoother or previously painted masonry gets a masonry sealer or primer. Benjamin Moore also says surfaces with a pH of 10 or more must be primed with a masonry sealer or high-build masonry primer, and new masonry must cure 30 days first.
Yes, if they are dry and you choose products rated for the location. Benjamin Moore's block filler data sheet says it is not recommended below grade and is not a waterproofing sealer. Leaks, efflorescence and dampness have to be addressed first. Interior masonry primers and finishes then go on at 50°F or warmer.
Benjamin Moore lists its Ultra Spec Hi-Build Block Filler at 1 hour to touch and 2 to 3 hours to recoat at 77°F and 50% humidity, and says high humidity and cool temperatures lengthen those times. It must be applied at 50°F or warmer. Thick application into deep pores can also take longer to dry.
Common causes are moisture moving through the block, efflorescence (mineral salts) under the paint, painting new masonry before it cured, or skipping a masonry sealer on alkaline surfaces. Benjamin Moore requires new masonry to cure 30 days and surfaces with pH of 10 or more to be sealed or primed before painting.
Sources: Benjamin Moore Ultra Spec Hi-Build Masonry Block Filler (571) technical data sheet; Benjamin Moore Ultra Spec Masonry 100% Acrylic Sealer (608) technical data sheet; Benjamin Moore Ultra Spec High Build Masonry Primer (N609) technical data sheet; Benjamin Moore Ultra Spec Masonry Elastomeric Waterproofing Coating (359) technical data sheet; Benjamin Moore Aura Waterborne Exterior Soft Gloss (N632) technical data sheet. Figures checked October 2026.
Licensed PA126039. $1M insured. Free written estimates after an on-site visit.
Book Free Estimate Call (610) 252-1815