Mountain Slate Blue reads as crisp and architectural — strong in modern spaces, with natural fixed elements (chrome, stone, glass), or as a quiet anchor. At LRV 18 it reads as a deep, enveloping shade — best on accent walls, dining rooms, and spaces where atmosphere matters more than reflected light. Skip it if you want a cozy, warm room — cool neutrals can feel sterile under warm bulbs or in low light.
Ref. #687788 · 10BB 18/106
Mountain Slate Blue
18%LRV Value
Mountain Slate Blue Technical Profile
What color is PPG Mountain Slate Blue (10BB 18/106)? It's a deep cool gray — hex #687788, LRV 18. The closest cross-brand equivalent to Mountain Slate Blue is Behr Always Indigo — a near-identical match on the wall, with Behr Hypnotic and Valspar Thundering Clouds also close. With an LRV of 18, Mountain Slate Blue creates a dramatic, enveloping mood — best on accent walls, dining rooms, and intimate spaces where atmosphere matters more than reflected light. As a cool neutral, Mountain Slate Blue pairs with cool whites for trim, gray-toned or rift-cut oak floors, and brushed nickel or polished chrome hardware. Black accents and natural greenery add contrast. As a deeper neutral, Mountain Slate Blue reads as a confident anchor — strongest on accent walls, cabinetry, and moody whole rooms that get enough natural light to keep it from going flat. Cool neutrals hold their crisp quality under 4000K+ daylight bulbs. Under 2700K warm light they soften considerably — particularly true for any blue or green undertone. Deeper neutrals can read close to black in low light, so preview Mountain Slate Blue in the room's actual evening lighting, not just at midday.
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Colors Similar to Mountain Slate Blue
Closest digital match based on color values. Always verify with physical samples.
Recommended Pairings
Colors That Work With Mountain Slate Blue
Timeless pairing with clean white trim and a tonal accent wall
Side Walls
Mountain Slate Blue
#687788
Accent Wall
Tonal Shift
A warm shift that adds depth without clashing.
#7D7CA7
Trim & Molding
Pure White
Crisp white trim for a clean, traditional look.
#FFFFFF
Color Palettes for Mountain Slate Blue
Color harmonies based on color theory — each swatch links to the closest matching paint.
Opposite on the color wheel — creates vibrant contrast
Mountain Slate Blue Room Palettes
Color schemes built around this color — each swatch links to the closest matching paint.
Warm & Inviting
Warm tones with cozy appeal — welcoming and comfortable
Cool & Calm
Cool hues with soft contrast — serene and restful
Bold Contrast
Complementary hues with punch — dynamic and striking
Similar PPG Colors
Other PPG colors close to Mountain Slate Blue.
More gray colors from other brands
Cross-brand colors in the gray family — useful when you want a similar look from a different brand.
Mountain Slate Blue — Frequently Asked Questions
What colors match Mountain Slate Blue from other brands?
The closest cross-brand equivalents to Mountain Slate Blue are Always Indigo by Behr (a near-identical match), Hypnotic by Behr (a near-identical match), Thundering Clouds by Valspar (a near-identical match). These are ranked with the CIEDE2000 color-difference formula, which scores how similar two colors actually look to the eye rather than matching them by name — so they're the best options for getting Mountain Slate Blue's look in a brand your local store carries. Always confirm with a physical sample, since sheen and lighting shift the final result.
What is the LRV of Mountain Slate Blue?
Mountain Slate Blue has a Light Reflectance Value (LRV) of 17.9, on a scale where 0 is pure black and 100 is pure white. That makes it a deep, dramatic color best saved for accent walls, dining rooms, and cozy spaces where atmosphere matters more than reflected light. LRV is the most reliable guide to how light or dark a paint will read in a real room — more dependable than the swatch on your screen, which varies by monitor.
Explore More with Mountain Slate Blue
Related Reading
How to Match Paint Colors Across Brands
The science behind Delta E and CIEDE2000 — find a Behr equivalent of any Sherwin-Williams shade, or a Benjamin Moore alternative when your store is out of stock.
Paint Sheen Guide
Flat, eggshell, satin, or semi-gloss — the right finish for Mountain Slate Blue depends on the room. Here's how to choose.