electrochemical decay

[meldrum]

I have a 44 year old waterwitch that I am currently working on. I have noticed that when the cockpit was rebuilt by a previous owner, he used brass screws instead of bronze and as a result the screws have dezincified are now going a greeny white colour and starting to mildly affect the surrounding timber.
My intention is to replace the screws with bronze ones, coated in either varnish or epoxy before insertion. What I would like to know is which of the two would be best. And also is there any preparation I can use to neutralise the salts that have been created in the surrounding timber

 

[LittleShip]

White vinegar will neutralise the costic effect of EC Decay.

You should not need to coat the screws with anything, just use good quality silicon bronze screws.

Brass should only be used inside or where it will not suffer from a damp atmosphere (on a boat????) I only use SB screws now as I have replaced all brass ones.

Tom

 

[Seanick]

NOT epoxy, just dip them in a little grease/tallow or drag over a candle before inserting (less messy Matron!)
Agree with the vinegar. Will help neutralise the alkali salts.

 

[Peterduck]

I agree with what has been previously posted in the replies, but I would add that you should, make sure that the new screws are getting a good hold on the wood. If it is degraded enough, the wood will no longer hold on to the screws, and they will just turn uselessly. You would then have to drill out the rotten wood and dowel the hole. Couldn't you just curse people who use brass screws? Galvanised ones are another sin, as the galvanising doesn't last, and then you are left with a rusty steel screw.
Peter.

 

[meldrum]

to peter yes curse indeed, all the way to the bank thanks for you comments chaps. Will use the vinegar and probably replace the screws with the next size up, as the damage has not got too bad yet.