When the wooden drainer around your kitchen sink goes black .

This is caused by water sitting there.

You need to rub the grooves with very fine grade wire wool dipped in white spirit.

Dry off and coat with a mix of one-third boiled linseed oil (from a DIY shop) mixed with two-thirds white spirit, using a soft cloth. Leave overnight then remove any excess.

Do this every six months or so to keep the wood looking good.