Fellow Shadow Watchers, Following my recent query on possible reasons for incised letters in sandstone acquiring wear-resistant 'islands' around them Patrick Powers commented: > >I have always assumed that the lettering had been painted and so was >protected whilst a lot of the erosion took place. Then after the process >starts maybe it progresses like that. This phenomenon is seen a lot on >sandstone dials in the UK and so maybe painting in the letters is something >that should be encouraged? > I'm sure there must be many list members conversant with fluid flow who might be able to comment on a possible alternative which occurred to me viz. is it at all likely that turbulence caused by the deeply-incised lettering would somehow cushion the lettering and its immediately surrounding areas and protect them from wind-borne sand etc. while flat areas took it full in the face? Is the 'Coanda effect' luking somewhere in the background perhaps?
Just a thought. Tony Moss. -
