I do think that you're missing a point. Faffing around with paintbrusehes and toothpicks is to avoid damage. The context an artefact is found in is the information. The angle in the soil, the depth , the structure of the soil can all give viatl information. Say you go out detectoring and start pulling up 'A load of old fragments'. Congratulations, you have just destroyed any chance of mapping where the pices are, that means no hope of working out where the shell fell or any indication of what it might have been aimed at, or were it was fired from.