Culm balls aka coal bumbs were made from mine waste (powdery, shaley coal known around here as slack) by mixing the it with clay or manure and forming balls (bumbs). The bumbs were considered poor man’s coal in Ireland. Here’s an interesting page showing how the bumbs were made and how they were burnt. Has anybody heard of this technique being used in our area years ago? Or was this just a technique used in Ireland? Here is an interesting Irish web page showing how the bumbs were made and burnt.