Oxidised Zn anode

[TiggerToo]

I have an old anode I removed a while back. It is covered with a white salt, which I assume is Zn(OH)2.

Is it possible to remove this and continue using the anode? Should I do it chemically (how?) or by physical removal, e.g. with a wire brush?

 

[Slowtack]

Not advisable to use a steel wire brush as it affects the electrochemical properties of the anode I believe... Sand paper should be OK.

 

[vyv_cox]

Steel (iron) inhibits the action of anodes. The hydroxide can be removed by non-ferrous tools, angle grinder, abrasives, brass wire brush, etc

 

[NormanS]

Isn't it noticable how all the pear shaped anodes have a big lump of steel through them with tails with holes for fastening them to the boat. That doesn't seem to stop them from working.

 

[vyv_cox]

Isn't it noticable how all the pear shaped anodes have a big lump of steel through them with tails with holes for fastening them to the boat. That doesn't seem to stop them from working.

The iron is separate from the zinc. If the strap affected the action of the anode, attaching a zinc anode to a steel structure would be ineffective, which of course is nonsense. US military conducted considerable research into this, which no doubt you can look up. MIL specs limit Fe to very low levels.

 

[NormanS]

What I don't understand is why cleaning an anode with an ordinary (steel) wire brush is apparently a no no.
That's not going to change the molecular structure of the zinc, any more than the adjacent steel strap.
Earnest searching after truth.

 

[rogerthebodger]

The zinc anodes on my steel boat do get a white crud on then due to being in brackish water and I clean then off using a chipping hammer and Hydrochloric acid

https://flic.kr/p/WM5Qt4

After cleaning

 

[Boater Sam]

The zinc anodes on my steel boat do get a white crud on then due to being in brackish water and I clean then off using a chipping hammer and Hydrochloric acid

https://flic.kr/p/WM5Qt4

After cleaning

Well, painting it is not going to work either!

 

[rogerthebodger]

Well, painting it is not going to work either!

There is no painting on my anode but my boat is well painted under the water with antifouling and epoxy below the the antifouling.

Yes paint will protect the steel from rusting but an anode will also protect the steel from galvanic corrosion and help where he painting does not completely cover the steel of the paint film gets damaged like the bottom of the keel

 

[NormanS]

I think he's referring to the careless splodges of antifouling on the anode. I take mine off to clean them up, and don't replace them until the antifouling is done. Makes sense to me.

 

[rogerthebodger]

I think he's referring to the careless splodges of antifouling on the anode. I take mine off to clean them up, and don't replace them until the antifouling is done. Makes sense to me.

Well Yes

That picture was some time ago when I washed down and antifouled between tides whit a maxim tide range of 2 meters

These days I pull my boat put on a 25 ton trolly and keep it there between spring tides so have much more time to remove the anodes and clean down better.

I also now get 2 local guys to wash and paint the hull with a full 20 liters of antifouling again wit note time to give better protection with 2 fill coats and an extra coat tital 3 and the water line and the keel and chine leading edges.

This lsts a fill 2 years with little fouling