Trevor Appleton wrote:

Here we are in one of the driest parts of the country with only 16 inches of
rain in the 50 weeks up to two weeks ago, and our new ( 2 month old) oak
table and chairs are black with mould.

Are they under trees or something?

Any suggestions how to :

a) Get rid of it
b) Keep it away

Something is wrong. There is no way sooty mould can colonise oak unless
there is sugary sap being dripped or sprayed onto it. Even mine that get
liberally coated in bat droppings show no signs of mould at all after
two years in a similar north yorks environment (but slightly damper).

Eventually wood goes silver grey through UV damage and lichens start to
colonise it but you should not have sooty mould.

Regards,
Martin Brown