how do I remove tar from old railway sleepers

[Ivan MCKEE]

I have old railway sleepers round a raised flower bed. the tar from them has started weeping out how do I stop it or treat them

[homeowners]

The tar from <i>railway sleepers</i> (or <i>railroad ties</i> as they call them on this side) is creosote coal tar that's saturated the wood fibers during the process of creosote wood preservation. It will seep out for as long as the tie resists the rot (25-30 years). When it stops, the tie will begin to disintegrate.  So, I guess from the standpoint of its structural integrity, it's good that it's still seeping - it means that it's structurally solid.

I do not believe any treatment exists to stop the seeping.  I can't think of a feasible process that would remove the tar that's already impregnated the wood fibers. As far as removing it from the surface, any substance that's able to dissolve and remove coal tar is bound to be far more nasty than the tar itself. Gasoline dissolves and removes it well but it will make such a mess and will be so detrimental to your health that I would not even contemplate doing it. Not to mention fire hazard. I suppose paint thinners would work on it, too. But it won't stop the weeping, just remove what's already on the surface.

By the way, creosote is not a completely benign substance either (otherwise it would not be much of a wood preservative). The American Agency for Toxic Substances and Disease Registry recognizes creosote as a substance to watch

though compared to other stuff they list there it's not terribly bad.

Anyhow, all I can think of in terms of easing the weeping is perhaps plant flowers in a way that would cover the sleepers and provide more shading. They do seep more when they are warm, so the longer you can keep them in the shade the better.