Picture posting is enabled for all :)
Tonight I'm gonna set a 'normal' fire & see what happens.
we always called it slag as well,what did you call tiny tinder?lbb
[always called "slack" when I was a lad... :-\]
[Have you never tried plant pot trays and also mixing it with walpaper paste.
Used to light coal fires daily at the age of twelve -- rolled up and twisted newspaper, kindling, [small strips of wood ], then coal - and hope we didn't catch the chimney. ;D