How does Fathom blue (No.18 C 39) by BS 4800 compare with Johnstone's’s closest paints? The nearest match by perceptual distance is Johnstone's Dark Summit (ΔE 2.9, “near-identical”). 3 more Johnstone's colours sit within ΔE 4 — close enough that the difference is hard to spot once paint’s on the wall. These 4 Johnstone's paints are all priced at £12.36 per litre.
BS 4800 Fathom blue vs Johnstone's
4 closest Johnstone's matches ranked by ΔE
ΔE (CIEDE2000) is a perceptual distance metric — lower means a closer match. Matches under ΔE 2 are typically indistinguishable; ΔE 2–4 looks “the same” once dry on a wall; ΔE 4–6 is noticeable side-by-side. Always view a sample pot before committing — screen colours and lighting vary.
| Colour | Number | ΔE | Match quality | Price/L | Price/m2 |
|---|---|---|---|---|---|
| Dark Summit | — | 2.9 | near-identical | £12.36 | £2.06 |
| Star Blanket | — | 3.1 | very close | £12.36 | £2.06 |
| Dark Energy | — | 3.3 | very close | £12.36 | £2.06 |
| Dark Water | — | 3.8 | very close | £12.36 | £2.06 |