"Tenex" wrote
if you're using creosote then some grades can be sprayed using a
standard cheap garden pressure sprayer.

Which inspired me to chase up the current rules on Creosote. Best I
found was http://www.hse.gov.uk/hthdir/noframes/creosote.htm It's no
longer even legal to use up old stock bought before the ban, it seems.

It's still available for industrial processes, but the controls are
severe.

If you google for 'creosote substitute' then there are a few availble,
and I have bought one from a local hardware store. Not sure I'd put
it in a sprayer, though, any more than I would old fashioned creosote.