The scaffold is up and the roofers are here ready to re slate my roof. Some time in the distant pass the existing old slates were unfortunately covered in some kind of Hessian and bitumen, I think they call it ‘turnerised’ or ‘tannerised’ or perhaps ‘terrorised’ which all now looks a bit flaky in parts. I think this was probably done as a cheap option to prevent slipping slates and to give the roof a few more years of life. Now that these slates are being taken off, we’ve discovered that the underside on a large proportion of the slates doesn’t look too bad, however some are a tiny bit flaky here and there not to mentioned stained from the lime torching etc. Would it be wise to simply reuse these slates by turning them over to the good side?