Color spec
| Brand | Dunn-Edwards |
| Name | Iron Mountain |
| SKU | DET637 |
| Hex | #5C5C5A |
| RGB | 92, 92, 90 |
| HSL | 60°, 1%, 36% |
| LRV | 11 |
| Undertone | neutral with no strong undertone |
| Family | Gray |
What Color Is Iron Mountain, Really?
Iron Mountain (DET637) is a deep charcoal gray from Dunn-Edwards. Its hex value is #5C5C5A, and the measured color has almost no saturation, so it reads as a clean, near-neutral dark gray rather than a brown or blue charcoal. With an LRV of 11, it sits firmly in the dark end of the scale and holds its depth without turning to flat black.
Dunn-Edwards positions it as their charcoal of choice for fences, doors, and modern exteriors, and that is exactly where it earns its keep. It gives strong contrast against white trim and lighter siding without the harshness of a true black.
It suits homeowners who want a grounded, architectural look: modern and transitional exteriors, front doors, board-and-batten fences, and interior accent walls or cabinets where you want weight and shadow rather than color.
Iron Mountain is about as neutral as a charcoal gets. Its saturation measures roughly one percent, which means it has no meaningful undertone pulling it warm or cool. On most walls it simply looks like dark gray, the color of wet slate or a graphite pencil.
Because the tiny amount of hue that exists leans very slightly warm, Iron Mountain can look a hair softer next to a crisp blue-gray, but that difference is subtle and only shows in direct comparison. Set beside a true warm greige it will read cooler; set beside a cool steel gray it will read a touch warmer. That neutrality is the point.
Test it against a bright white card and against a paint chip you know is warm. If Iron Mountain still looks like plain dark gray next to both, you are seeing it correctly. Always view large samples in the actual room before deciding.
Best Rooms and Uses for Iron Mountain
At LRV 11 this is a statement and contrast color, not a whole-room light. On exteriors it shines as a body color for modern and farmhouse-modern homes, and it is a natural pick for fences, garage doors, and front doors where you want depth against white or light siding.
Indoors, use it where drama is welcome. It makes a strong accent wall, a moody powder room, or a fireplace surround. It is an excellent cabinet color, especially on a kitchen island or lower cabinets paired with lighter uppers and a pale counter, and it reads well on built-ins and interior doors.
Avoid it as the only wall color in a small, dim room unless you want a cocooning, cave-like feel. As trim on a light-walled room it adds sharp definition. For full-room walls, reserve it for spaces with generous natural light or strong artificial lighting.
How Lighting Changes Iron Mountain
With an LRV of 11, Iron Mountain absorbs far more light than it reflects, so lighting has a big effect on how heavy it feels. In bright, direct sun it opens up and shows its gray clearly, which is why it works so well on exteriors and fences that get full daylight.
In north-facing rooms and on shaded elevations, the light is cooler and weaker, so Iron Mountain can look almost black and quite moody. South-facing spaces keep it lively and clearly gray for most of the day. East light reads cool in the morning, and west light warms it up in the late afternoon.
Indoors, warm bulbs around 2700K keep it from going cold and are the safest choice. Cool daylight bulbs push it toward a flat, slate look. Because it is so dark, give it good ambient and layered light so it does not swallow the room.
Most complaints about Iron Mountain are a light mismatch. Upload a photo of your actual room and see it on your walls — then ask for the same wall in north light or evening lamps before you buy a single sample.
TEST IT IN YOUR LIGHT →Iron Mountain vs Similar Colors
Iron Fixture (DE6384) at LRV 10 is nearly the same depth and warmth as Iron Mountain, just a fraction darker. In practice the two are hard to tell apart on a wall, so choose whichever your fandeck or contractor has closest to hand; the visible difference is minimal.
Charcoal Sketch (DET628) at LRV 11 matches Iron Mountain for lightness but carries a slightly warmer, more brown-leaning base. If you want the charcoal to feel a touch softer and less pure-gray, Charcoal Sketch does that; if you want a cleaner neutral, stay with Iron Mountain.
Marengo (DEGR54), also LRV 11, is the cooler alternative of the group, with a faint blue-green cast. Pick Marengo when you want a steel-gray feel, and Iron Mountain when you want a neutral charcoal that does not commit to warm or cool.
Colors That Go With Iron Mountain
For trim and ceilings, a clean high-reflectance white gives the crisp contrast Iron Mountain is built for. Whisper (DEW340) at LRV 84 is a soft, near-neutral white, and Swiss Coffee (DEW342), also LRV 84, is a slightly warmer creamy option if you want the pairing to feel less stark.
For a second, lighter wall color or a stepped-down exterior tone, Battleship Gray (DET636) at LRV 22 stays in the same neutral family and reads as a natural mid-gray companion. On the accent side, Maiden Voyage (DEA178), a deep blue at LRV 8, makes a handsome front door against an Iron Mountain body, and Sequoia Dusk (DET668), a warm brown at LRV 14, brings a wood-tone accent that softens the whole scheme.
Iron Mountain also sits well with natural wood, brushed nickel, and matte black hardware, which pick up its neutral, architectural character.
Need It From Another Brand?
Any paint counter can custom-tint Dunn-Edwards DET637 directly — but if you would rather stay in one brand's own deck, these are the closest stock matches:
Similar Dunn-Edwards colors
closest in the Dunn-Edwards deckThe nearest shades to Iron Mountain within Dunn-Edwards's own range, ranked by perceptual color distance — useful when you want the same look a touch lighter, darker, or warmer.
Coordinated palette
Generated by hue-rotating #5C5C5A in HSL space. Pair Iron Mountain with one accent and one neutral — the swatches below are starting points, not final picks.
Accessibility (WCAG contrast)
WCAG 2.1: AA = 4.5:1 normal text · AA Large = 3:1 large text · AAA = 7:1 normal text.
The Questions Everyone Asks
Is Iron Mountain warm or cool?
Iron Mountain is essentially neutral. Its saturation is only about one percent, so it has no strong warm or cool undertone and reads as a clean dark gray on most walls. The faint hue it does have leans very slightly warm, which keeps it from looking cold, but next to a true warm greige it will still read as neutral charcoal.
What trim white goes with Iron Mountain?
A bright, high-LRV white gives the crisp contrast this charcoal is made for. Whisper (DEW340) at LRV 84 is a soft, near-neutral white that keeps the pairing clean. If you prefer a warmer, creamier trim, Swiss Coffee (DEW342), also at LRV 84, softens the contrast slightly while still standing out clearly against the dark walls.
Does Iron Mountain work on cabinets and exteriors?
Yes to both. Dunn-Edwards positions Iron Mountain as its charcoal of choice for fences, doors, and modern exteriors, and it holds up well as an exterior body or door color. On cabinets it works especially well on an island or lower cabinets paired with lighter uppers and a pale counter, where its depth adds contrast without going fully black.
What does Iron Mountain's LRV of 11 mean in practice?
An LRV of 11 means Iron Mountain reflects only about eleven percent of the light that hits it, so it is a genuinely dark color. It reads as a statement or contrast tone rather than a light neutral. Give it strong natural light or warm artificial lighting; in dim or north-facing rooms it can look nearly black and quite moody.
How is Iron Mountain different from Peppercorn?
Peppercorn (HGSW 1491 from HGTV Home by Sherwin-Williams) is a very close match at LRV 10, just a shade deeper than Iron Mountain's LRV 11. Both are neutral charcoals, so on a wall the difference is small. Iron Mountain is the Dunn-Edwards option if you are already buying that brand; the practical choice usually comes down to which paint line you are using.
Should I sample Iron Mountain before painting?
Definitely. Because it is so dark, Iron Mountain shifts noticeably between bright and shaded light and can look near-black in dim rooms. Paint a large sample, ideally two coats, and view it on different walls at morning, midday, and night before committing. Check it against your trim white and flooring too, since contrast is a big part of how this charcoal looks.
Will It Work in YOUR Room?
No page can promise how Iron Mountain behaves in your light. Upload a photo and see it on your own walls in seconds — before you spend a cent on samples.
TRY IRON MOUNTAIN ON YOUR ROOM →
Ask a Question