What colour ballast is generally used?
Hey, I use fine gray blend ballast, as do most modelers. However, for Thomas and friends, some spots appear to have more of a buff color. You can check them all out at woodland scenics website, however, Bachmann makes ballast too> i cant tell you how it is as I have never used it before.
Thanks SodorAdventures, having since reviewing a whole bunch of videos you are correct on both colours. It appears during the early years they used what looks like buff or brown depending on the light but in the CG series it changed to gray.