Focus on UK Metal Detecting: What's best?

A question on a metal detecting forum near you: "Whats the best thing to use to darken finds?" (Wed Nov 13, 2013 2:25 am) and the PAS outreach answer is?

Why would people "researching their local history" and "contributing to our knowledge of the past" want to "darken finds"? Do collectors of vintage cars, antiquarian books, postcards, pliocene fossils, Queen Victoria -George V postage stamps, old pens, clocks, antique cameras or anything else want to give the objects they own a muddy brown colouring?

What is the logic behind that if we are to see artefact collectors as some kind of amateur historians/archaeologists? What does the fact that they are splurging oil or wax over the artefacts to change their colour and appearance tell us about what they are really doing?  When are the PAS going to step out of line and have a gentle word with their "partners" and be consistent with the picture of the hobby that they are fobbing the rest of us off with and say something when issues like this arise? Where is the PAS outreach (really)?

 Vignette: Wikipedia tar.