Rub 'n Buff is similar to gilding wax.
Yep, it is gilding wax, original use was picture frame highlighting etc.
The pewter would probably work for gunmetal, mixed with a bit of
silver works for steel.
Just a bit messy to mix, and the gilding wax I’ve used is a bit stiffer
than Rub n Buff.
![Grin ;D](http://beyondthesprues.com/Forum/Smileys/clabIcons/grin.gif)
If you look at the Amazon UK link, Rub n Buff is one of the more
expensive options over there.