So sharp you won't cut yourself

Yes, I confess, this is a staged photograph. Our kitchen doesn't look like this though, if it were big enough and one of the corners could be veiled off, this is what you might see behind the curtain. It's all to do with that urban (domestic?) myth that you're more likely to injure yourself with a blunt knife than a sharp one. A dull knife means you need to exert more pressure and that pressure may get misdirected.

Our arsenal of sharpeners starts with the steel in the foreground. It was quite expensive and the blade is embedded with diamond dust. It's OK for toning up a knife that has merely lost its edge but it's not the device you'd use if, for urgent reasons, you needed to convert a butter knife into a carver.

To the right is a Carborundum stone held in a wooden frame. This is slowish but eminently controllable and I would use it to transform a really blunt knife if it were also necessary to maintain the appearance of the blade.

Finally the double grinding wheel with the non-optional safety glasses. Brush one side of the knife blade against the wheel for five seconds, then the other side. The device is ugly, surprisingly cheap, belongs in a workshop and is frighteningly efficient.

TECHNO-ART "Rififi" is a French burglary caper film that predates the word caper. Famous for the 15-minute passage without dialogue. It's particularly good on the technology of burglary. Entrance to the target room is made down through the ceiling and the thieves need a method of preventing debris from dropping on to the floor below and starting the burglar alarm. Simple - insert a folded umbrella through an initial small hole then open it up. Immobilise the burglar alarm? Squirt the contents of a fire extinguisher into it.