In message , Jonathon
writes
I have half a dozen old railay sleepers which form
raised beds leaking tar. How do I seal them?

Thank you

I'm not sure it is possible. Possibly some readers of this group will
know of ways to manage this but I have several raised beds and other
constructions made out of old sleepers and have learned to live with it.
Any sleepers I buy now are inspected prior to selection.
--
Gopher .... I know my place!