I have created raised beds using railway sleepers cut to size and
fixed vertically. The cut ends are starting to turn white as they
weather.

What can I treat them with as I like the previous dark colour.

I tried the new 'safe' creosote but it soaked it in and I used two
mugs full on just one sleeper end and it was not very dark, no where
near as dark as the sides of the sleepers.

Regards

Nick