If you have left your furniture outside and its colour has become slightly grey, you can restore its original colour by sanding it with fine sandpaper (no. 220). You can also get rid of the grey (oxidation) by using oxalic acid or a teak brightener specially made for this operation. Use a medium-hard brush in order to clean the teak and get rid of any dirt or dried fibres on the surface. Then apply the deoxidizer with 00 steel wool. Wait 24 hours and apply a coat of oil to preserve its original colour.