RAL 840-4 vs Thames Fog
Where RAL 840-4 belongs to RAL Effect's range, Thames Fog is a Valspar color. Both sit in the grey family, which is useful context if you're narrowing within a single hue direction. Thames Fog (LRV 27) reflects noticeably more light than RAL 840-4 (LRV 21), a difference of 6 points that becomes especially apparent in rooms with limited natural light. The ΔE 6.6 gap is real but not dramatic — close enough to use together, distinct enough to matter as a choice. Below you'll find 4 real-room photo comparisons where both colors appear side by side, plus 5 simulated room previews.
RAL 840-4 vs Thames Fog in Real Spaces
4 real rooms side by side. RAL 840-4 and Thames Fog are close enough that the difference can be hard to judge from a chip alone — these photos show how each reads at scale, across different spaces and lighting conditions.
Living Room
In a living room, color works across both daylight and evening light — the same wall can read very differently at noon and at 8pm. The brightness difference is modest but present — Thames Fog gives the walls a little more lift.
Bedroom
The context that matters most in a bedroom is how a color reads under a bedside lamp at night, not under noon daylight. Thames Fog reads slightly lighter here — a subtle but real difference in how open the space feels.
Bathroom
Bathrooms are one of the few spaces where you're genuinely enclosed by the paint color, which makes the choice between these two more consequential. Thames Fog reads slightly lighter here — a subtle but real difference in how open the space feels.
Kitchen Cabinets
Kitchen cabinets are constantly compared against adjacent materials, which means subtle differences between these two become much more visible. Thames Fog reads slightly lighter here — a subtle but real difference in how open the space feels.
Color Details
RAL 840-4 vs Thames Fog Simulated Comparison
5 simulated room previews — drag the slider on each to see RAL 840-4 on one side and Thames Fog on the other.
Digital color is approximate. These simulations are generated from the manufacturer's hex values and overlaid on grayscale room photos — your screen's calibration, brightness, and viewing angle all affect how they render. Before committing to either color, test physical samples in your own space under the light you actually live with.
More RAL 840-4 comparisons
See how RAL 840-4 stacks up against other well-photographed colors across different brands and tones.
