The right mix

It’s a pity Ian Brixey feels he is stereotyped as a nerdy, badly-dressed, socially inept dweeb (Letters, 14 July). I am a retired engineer and have never felt anything of the sort.

Nevertheless, Shirley Batten raised in her coffee-stirring letter (Talking Point, 30 June) what is an important issue in many branches of industry, where appropriate methods of mixing save significant time and money. The answer to her question is that mixing is efficiently achieved by creating turbulence (the figure-of-eight motion her engineer colleague uses being a good example). Her rotational stirring method, which results in essentially laminar flow leads to poor mixing.

Chris Finn, East Yorkshire