Dezincification ?

[PaulJ]

I am giving a friend a hand with checking/changing the skin fittings on his quite elderly fibreglass boat. Having cleaned it up with a rotary wire brush, one fitting is giving me some concern because it is quite pink in colour. It is a very uniform colour and I am not sure if the colour is because it has dezincified or because it is just quite a pink bronze. I have an old propellor which had dezincified but on that the pink is much more "blotchy" and unfortunately all the other fittings are different so we have nothing to compare it with. So.... I know it is difficult to say without seeing it but can anyone tell me if dezincification ever appears completely uniformly or is this fitting just made of a rather coppery bronze and is probably perfectly OK?

 

[cliff]

Take a file and give the surface a good filing and see if the colour changes once you have gone in about one millimetre. If colout still pinkish then I would suggest the fitting is O.K. but for the cost of a new fitting why take the risk?
----------

 

[boatmike]

Sounds like dezincification to me but the test is to go inside the boat and look at the outside of the fitting where it is not exposed to seawater and compare to the bore and bit outside the boat which is....

 

[PaulJ]

Thanks chaps. I found a surveyor in the yard today and asked him...... He said that it was certainly pink and that dezincification had started but, after scratching and tapping it, said that it was not bad and could still be used.

The reason we did not want to replace it is that this fitting is a sink outlet and the available replacements, though they have the same outside diameter (3/4"bsp), have a slightly smaller inside diameter and use internal lugs to enable some "purchase" when tightening the nut. It was felt that this combination of lugs and smaller i.d. could cause it to block so we would prefer to reuse the old fitting if possible. So we have refitted it and made a note to check it again next Winter.

Thanks again for your responses.