A very dilute solution of hydroflauric acid is generally considered to be suitable for removing ingrained dirt from the facings of old brickwork.

Of course the condition of the bricks needs to be checked before you start as any eroded bricks will be damaged further by the acid. The mortar pointing should also be in good condition.

Unfortunately hydroclauric acid isn’t nice stuff to use, so protective goggles, masks and gloves etc need to be worn at all times.

 Dilute the acid, work in small areas at a time, and then wash it down thoroughly with a high pressure hose.  Bear in mind that very wet ricks can absorb damp through to the inside of a solid wall, so try not to soak the walls for longer than necessary.

Work from top down, so that the areas you’ve already cleaned aren’t then stained with dirt from above.

Don’t leave the chemical on the brickwork for too long, as making the bricks ‘overly clean’ may not look appropriate on a Victorian house.

It is essential to carefully mask windows and openings, as the acid can etch the glass making it obscure.

Alternatively, alkali based cleaners can be used, but these are not so and easy quick to use.