<sod>Alum solution has the property of dissolving steels while not affecting aluminium or [[base metals]], and can be used to recover workpieces made in these metals with broken toolbits<ref>https://www.youtube.com/watch?v=fqZYgReuywM AvE demonstrates usage of Alum to remove a broken stud from an aluminium engine head</ref> lodged inside them.<ref>http://www.model-engineer.co.uk/forums/postings.asp?th=91442&p=82#PostTop</ref> As considerable expense and/or effort may have gone into machining a specialist part, this can be a worthwhile exercise.{{citation needed|date = September 2016}}<eod>
<sod>Alum solution has the property of dissolving steels while not affecting aluminium or [[base metals]], and can be used to recover workpieces made in these metals with broken toolbits.<ref>https://www.youtube.com/watch?v=fqZYgReuywM AvE demonstrates usage of Alum to remove a broken stud from an aluminium engine head</ref> lodged inside them.<ref>http://www.model-engineer.co.uk/forums/postings.asp?th=91442&p=82#PostTop</ref> <eod>