What, with bird droppings, barbecue drippings and various other indignities, your terrzace is a sorry sight. To give it a good eco-friendly clean, black soap or Castile soap is the super hero and your better half its faithful assistant.
Explain to Raymond that all he needs, to give the terrace and the tiles a total make-over, is a bucket of hot water with 2 caps black soap or Castile soap and a scrubbing brush. The result is short of miraculous without damages to the planet or humans. The dear boy will be totally bluffed.
Horrible grease stains are disfiguring the terrace stones? Tell him to wet the offending blemishes with sparkling water and to prepare a bucket of very hot water with 2 caps black or Castile soap and 1 glass vinegar. Some vigorous scrubbing with a deck-broom, followed by a good rinse, will eradicate these non gratae, while giving his pecs and biceps a great workout.
Tiles and slate respond brilliantly to the same treatment. Systematically squeegee after rinsing to ban any water marks. If some ghastly white stains are spoiling the looks of your sublime slate slabs, the culprits are mineral deposits, hard to eradicate, especially on ancient slate. A double dose of black soap or Castile soap, i.e. 4 caps, should dislodge them.
Garden furniture loves black soap or Castile soap. For aluminium pieces, wrought iron, plastic and PVC, resin, braided resin and wicker ones, the recipe remains the same: 2 caps in a bucket of warm water, but cleaning is done with a sponge. Ditto for canvas, which needs to be brushed with a very soft brush under running water for instant rinsing.
Pieces of painted metal, inflatable PVC or synthetic fibres, respond well to a pinky nail-sized squirt of black soap on a wet cotton sponge, followed by a good rinse with water.
As for the barbecue, after a busy evening, it needs a total degreasing. Tell the specialist to put a few drops black soap or Castile soap on a washing-up brush, scrub energetically and rinse with very hot water.