Brick absorbs paint like a sponge with channels running in three directions at once. The fired clay surface, the textured face, and the mortar joints all have different porosity levels, different surface energies, and different mechanical profiles. Roll paint across unpainted brick without a primer and roughly 40 percent of the first coat disappears into the substrate before it even begins to build a film. Understanding how to work with that porosity, rather than fighting it, is what separates a clean, lasting paint job on interior brick from one that looks chalky, uneven, and faded within a year.

Cleaning and Prepping Brick for Interior Paint Adhesion

The prepping sequence for interior brick starts with understanding what is on the surface. Fireplace brick accumulates three categories of contamination: soot deposits from normal use, efflorescence (white mineral salt deposits that migrate from within the masonry), and dust and debris from decades of combustion byproduct. Each category requires a different treatment and skipping any of them creates adhesion problems that show up after the paint is on.

Soot is the most common issue on fireplace brick. It contains carbon particles, tars, and incomplete combustion residue. These compounds are incompatible with water-based paint binders. Painting over soot without removing it results in the soot bleeding through lighter topcoat colors, particularly whites and creams, and compromises adhesion at the same time. Clean soot with a TSP (trisodium phosphate) solution applied with a stiff natural-bristle or nylon brush. Mix the solution according to the package directions, scrub the brick face and mortar joints thoroughly, and rinse completely with clean water. Allow the brick to dry for 24 to 48 hours before proceeding. Brick holds moisture internally for longer than its surface suggests.

Efflorescence appears as white, powdery, or crystalline deposits on the brick face or in mortar joints. These are water-soluble salts that migrate to the surface as moisture moves through the masonry. Painting over efflorescence creates a serious adhesion problem because the salts continue migrating after the paint is applied, pushing the film away from the surface from beneath. Remove efflorescence mechanically with a wire brush before any wet cleaning, then use a masonry cleaner or diluted muriatic acid solution to fully dissolve the deposits. Wear eye protection and chemical-resistant gloves when working with acid solutions.

After cleaning, inspect the mortar joints for cracks or voids. Fill damaged joints with pre-mixed mortar or a masonry patching compound. Allow repairs to cure fully, typically 24 to 72 hours depending on depth, before priming. Fresh mortar is highly alkaline with a pH of 12 to 13, which limits paint adhesion and can cause yellowing in some formulations. If joints were recently repaired, allow 30 days before painting.

The firebox interior requires a separate note. Standard interior paint should never be applied inside the firebox where flames and hot gases are present. Any surface inside the combustion chamber requires a high-temperature paint rated for 1,200 degrees Fahrenheit or higher. The brick on the fireplace surround, above the firebox opening, and on the mantel does not reach temperatures that require specialty paint. Those surfaces stay well below 180 degrees Fahrenheit during normal use and are appropriate for standard interior paint products.

Best Primer for Porous Interior Brick Surfaces

Primer on brick is not optional. Brick is highly porous, and without a sealing primer coat, the first application of topcoat disappears into the substrate rather than building an even film. The result is a blotchy, uneven appearance that requires additional topcoat applications to correct.

KILZ 2 Interior/Exterior Water-Based Primer is the most commonly recommended primer for interior brick fireplaces by professional painters. It provides adequate sealing for most brick porosity levels, works with both water-based and oil-based topcoats, and is widely available at hardware stores. Apply it by cutting in around the mantel detail with a brush and rolling the broad brick faces with a thick-nap roller.

KILZ 3 Premium handles situations where KILZ 2 leaves the surface under-sealed. It works on woodwork, drywall, plaster, masonry, brick, and painted metal, making it useful as a single primer across the mixed surfaces of a fireplace surround that includes both brick and wood mantel components.

KILZ Premium Primer is the appropriate choice when efflorescence remains on the surface despite cleaning efforts. Its higher solids content provides better encapsulation of residual mineral deposits.

For chalk paint applications on brick, no primer is required. Rust-Oleum Ultra Matte Chalked Paint (product number 285140) is the top-cited chalk paint choice for brick. Chalk paint application allows for a German Smear technique where the paint is applied thinly and partially wiped, allowing the original brick texture and color to show through in a translucent layer. This creates a period-appropriate whitewashed appearance without fully covering the brick.

Allow primer to dry for the full recommended time before topcoat. On brick, which is porous and absorbs moisture from water-based primer, allow at least 2 to 4 hours and up to 24 hours if the brick absorbed the primer heavily (visible as dull, flat spots where the primer soaked in rather than sitting on the surface).

Brush vs Sprayer for Getting Paint Into Mortar Joints

Mortar joints are where the painting method makes the most visible difference on brick. A joint that is not fully painted looks darker than the surrounding brick face and creates a striped, unfinished appearance. Getting paint into a 3/8-inch or 1/2-inch recessed joint requires either mechanical forcing or the right tool combination.

Roller application on brick uses a 3/4-inch to 1-inch nap roller to reach into the mortar joints while loading the flat brick faces. At this nap thickness, the fibers compress against the brick face and spring into the joint as the roller passes. The brick’s texture also creates sufficient friction to pull paint off the roller into the recesses. Load the roller fully, apply with moderate pressure, and avoid fast passes that skip over joint recesses.

Back-brushing after rolling is the technique that closes the gap. After rolling a section, immediately follow with a stiff natural-bristle brush to work paint deeper into mortar joints and into any crevices the roller missed. Use short scrubbing strokes directed into the joint. This step is critical on older brick with variable joint depth, weathered mortar, or significant texture variation.

Sprayer application covers mortar joints more completely than any roller-and-brush method. An airless sprayer atomizes paint into droplets that follow the contours of the surface into recesses the roller cannot reach. For large fireplace surrounds with deep mortar joints or complex brick patterns, spraying the prime coat and first topcoat provides more uniform coverage before back-rolling. Spraying indoors requires careful masking of the surrounding area, including flooring, hearth, and the interior of the firebox. Any masking tape on the firebox interior should be removed immediately after spraying.

For most residential fireplace surrounds, a roller with 3/4-inch to 1-inch nap combined with back-brushing on the mortar joints is sufficient and produces a clean result. Reserve the sprayer for situations where the fireplace surround is large, the mortar joints are deep, or the brick pattern is highly irregular.

How Painted Brick Changes the Look and Feel of a Room

Painting a brick fireplace surround is one of the more significant visual transformations available in a room without structural changes. Raw brick carries a strong visual texture and a warm, earthy color palette that dominates the space around it. Painted brick does the opposite: it softens the visual weight of the masonry, unifies the color palette, and allows other elements in the room to come forward visually.

White and off-white are the most common paint choices for interior brick fireplaces, partly for aesthetic reasons and partly because they are the most forgiving colors to apply uniformly over a surface with the variability of brick and mortar. Light colors require thorough coverage of mortar joints to prevent the original gray or brown joint color from creating a grid pattern through the topcoat.

Dark paint on brick, particularly matte black or charcoal, has grown in popularity as a counterpoint to the whitewashed look. Dark colors require fewer coats for full hiding because the brick’s natural color sits in the same tonal range. The visual effect is dramatic rather than softening, pulling the fireplace forward as a focal point rather than allowing it to recede.

The sheen choice affects how much of the brick’s texture remains visible after painting. Flat and matte finishes absorb light and minimize the appearance of texture variation, giving painted brick a more uniform, quiet look. Satin introduces enough light reflection to highlight the dimensional variation between brick faces and mortar joints, creating a livelier visual surface. Semi-gloss on brick calls significant attention to every texture variation and is rarely appropriate for fireplace surrounds.

Chalk paint matte finish is consistently popular for interior brick because it provides the highest visual warmth and the lowest gloss of any widely available product, while its thicker viscosity and quick dry time make it easy to control on a complex, textured surface.