Ian: the ash ballast is, well, ash! Ash from the fire crushed down and sieved to a fine grain and then laid as normal ballast would be. Some different coloured ashes were used in different locations (e.g. where locos stand and outside the shed). I think some powdered chalk was also used to add different colours, such as the reddish tinge to the Down line where the full ore trains would deposit pellets along the track.
Hope this helps,
Arp
Hi Arp and friends. I didn't notice this about the ash on first browse. I have a wood pellet boiler at work and the ash/residue is really good for various scenic uses including ash!!!! It is a bit messy and varies in consistency from almost dust to granules which would be good in 4mm for slaggy coal or slag or similar! Most of the stuff though is just the right scale for scenics, well in 4mm anyway. I also think it could be used by modern image bods as pulverised coal loads as on MGR. I could supply a picture of some of the stuff if required.
Very sincerely, 36E