When I was very young I asked my great-grandmother why the area under the fingernails got so dirty and had to be washed and what was it that collected there and where did it come from. She replied [roughly] that it was due to what was called ‘toiler’s clay’ carried out of our bodies with sweat because we worked so hard and scratched our bodies with our fingernails.
Nobody I have tried to use the term with has ever heard of it.
I have looked for reference to the term but have failed to find any.
Has anyone here ever seen or heard the term ‘toiler’s clay’