Getting tar off railway sleepers??

[ReshapeWhileDamp]

We recently moved to a house with a raised bed at the corner of the patio that I don't want to get rid of. Two of the sides are made from old railway sleepers - quite nice-looking, BUT they are now oozing tar in the sunshine. DS1 is ruining his trousers and shoes because he likes sitting and walking along them.

Can it be coated in any way? Surely it'll bubble through? (please tell me it will, so I can tell DH and stop him going on about painting them! ) Scraped off? Is there anything I can apply that will encourage it to come off?

My other plan is to get some planking and mitre them to sit on top of the sleepers, so we can sit next to the herb bed but not sully our trousers. But they are hard as iron, so it'll be an effort to get nails in.

We never managed to find a away of getting rid of it. It didn't effect a huge area of our sleepers, so I tried scrubbing it off, but the next sunny period and more oozed out. Ended up planting plants that hung over that bit. (But it didn't get rid of the smell, which was always worst on sunny days...) I'm not convinced that painting would work, as think it would bubble up... You can get sleepers that haven't been treated, so you could replace them?
Sorry - not much help.
madcows

It isn't just painted on, they are pressure-soaked in the stuff so there is a massive amount to come out.

It will probably keep coming out through the paint.

It's carcenagenic, which is why you can't buy 2nd hand sleepers any more, only new (fake, untreated) ones. Don't grow edible plants in beds made with them, as it will leach into the soil and into the plants.

... oh bum.

Surely it's not seeping through the soil in carcinogenic amounts, though? I mean, a barbeque produces carcinogenic food but we all nosh on!

Don't know! I just know that's why the railway can't even give them away.

Mind you, people have used them for years.

Could you top the sleepers with slabs? Not so pretty but if they are fixed on (concrete/mortar?) then DS can sit on them.

Slabs won't work really - the bed is triangular, the cut-off corner of the patio, with two sleepers forming the outer walls of the bed. The plants are growing at a lower level than the tops of the sleepers.

I think planking might be the best way forward, but not sure if we can hammer nails into the sleepers. Maybe a drill and a really tough drill bit??

Some kind of superstrong wood glue? How do they put boards onto houses? They are on stone. There must be a way!