Oak Sleepers + Galvanised Steel

[Temmy]

Hey folks,

When screwing into oak, I've always been told that stainless steel is what you should use. However, when it comes to brackets and things that sit against an oak sleeper, is there any harm in using galvanized steel? The screws attaching it would all be stainless, it's just the metal bracket itself would be galvanized.

Ta.

 

[Deleted member 174758]

Same problem, really. Tanin in the oak will combine with water and dissolved sulphur dioxide in rainwater to produce a mixture of tannic acid and sulphuric acid. The sulphuric acid in particular will eat away the zinc plating, and once that is porous the tannic acid then reacts with the iron molecules in the steel to produce an indelible, black ferrous rust which stains oak. It is a slow process, but it happens wherever you have steel/iron, water and oak combined. For this reason "ironmongery" for oak from the Georgian period onwards was often brass or bronze, and more recently stainless steel. BTW hot dip galvanised lasts longer than electroplated zinc, but on the end it will still rust

 

[Temmy]

Thanks @JobAndKnock. Stainless steel it is all the time then!

 

[^woody^]

Put some tape or a bit of polythene DPC on the back of the bracket as a barrier