I have just made a pair of garden gates in Iroko and I'm intending to use Sadolin Classic (1 coat) and Sadolin Extra (2 coats) to finish them off. On reading the small print on both products it states that only non-ferrous screws nails and fastenings should be used.
I have used some zinc yellow passivated screws on my gates to fix the T&G facing boards to the gate structure.
I would be happy to change the screws for brass, but can't find any on t'internet. I need 4 x 45mm countersunk, posidrive preferably. (In a reasonable quantity, say a couple of dozen!)
What will be the effect, in the short term and long term, of leaving the screws in place and just going ahead with the Sadolin? Only the screw heads are showing, so there is minimal contact area between the screws and the finish.
Unfortunately because of the virus, Sadolin have temporarily suspended their technical advice line.

Cheers
Pete