Zimgrind - there is an expert amongst us who has taught me how to decontaminate my coins- this will not make it glow , change colour - or any other weird or wonderful things but what it will do is remove and surface grease etc without damaging your coins - just use acetone (not nail varnish remover ) with a cuetip and gently dab it on your coin.  With regards your toned 1908 penny there are many collectors who prefer toned coins. the question is what grade is it - many here can help you on that if you paste a pic or two.