Most ‘ugly’ old chimneys aren’t ugly, they’re buried: under 1980s paint, mismatched patch mortar, and decades of biological grime. Restoration of appearance is archaeology more than decoration, and the cardinal rule is that every step must be reversible-gentle, because the original face only exists once.
Step 1: subtract the damage-in-disguise
Step 2: repoint like the original mason
Color-and-chemistry matched mortar is half the look; tooling is the other half, the joint profile (grapevine, beaded, flush-struck) is the wall’s texture signature, documented from protected areas and reproduced by hand. Get the mortar right and the tooling wrong, and the wall reads ‘repaired’; get both and the work disappears into the original.
Step 3: replace in kind, where you must
Failed units swap for salvage or reproduction matched in size, color range, and texture, set with the good faces out, weathered consistency matters more than individual perfection; a too-new brick in an old wall shouts. The surviving-fabric assessment decides how much of this step exists.
Step 4: protect without shine
If treatment’s warranted, breathable siloxane only, the invisible chemistry, never film-formers, whose gloss is both aesthetically wrong and materially harmful on old brick. The finished face should look like nothing was applied, because functionally-visible ‘protection’ is the look you just paid to remove.