Casting anodes

[svrevelations]

I am curious about casting my own anodes.
Has anybody ever done this?
What is involved and how is this done?
Can this be done in a well equipped workshop or is it only for foundries?
Looking forward to your ideas and advice.

[Orchidius]

I have considered it as everybody at my marina seems to change anodes when they are 40% gone and they keep all the leftovers...

Technically it is very possible as the melting temperature is really low compared to other metals and a brick can act as a mould.

However, apart from dealing with molten metal I was warned for really toxic gasses.

All in all it is possible, but not really worth it unless you're doing it mostly for fun .

[svrevelations]

Originally Posted by Orchidius

I have considered it as everybody at my marina seems to change anodes when they are 40% gone and they keep all the leftovers...

Technically it is very possible as the melting temperature is really low compared to other metals and a brick can act as a mould.

However, apart from dealing with molten metal I was warned for really toxic gasses.

All in all it is possible, but not really worth it unless you're doing it mostly for fun .

Some proprietary anodes actually cost quite a bit than some plain old generic "brick" anodes in shops. Then, the South African currency is in a bad shape making it all more that expensive to import. So it is not just a fun project - it is also a financial proposition.

The idea is to buy the cheap stock standard anodes (or use the many old anodes lying around), melt and cast them into the required shape we need.

[noelex 77]

I have done it, but only because I could not buy the anode easily (it was an engine anode)
I did it outside (on the beach) so there was ample fresh air. The drawback is you need a lot heat, even with little breeze (I had 2 blowtorches and a gas hot plate). Moulds can easily be made even wood is OK for a one off.

Wear some eye protection, leather gloves etc

[fstbttms]

Anodes (whether they be zinc, aluminum or magnesium) are made of an alloy of metals and the best ones are made to miltary specifications. Will smelting spent anodes to be recast as new provide the proper metal ratios? Who knows? Unless you can duplicate these alloys, you are doing your boat a big disservice by putting homemade anodes on it, IMHO. Zincs are cheap but the result of improperly protecting your boat's metals can be expensive.

[perchance]

Originally Posted by Orchidius

I have considered it as everybody at my marina seems to change anodes when they are 40% gone and they keep all the leftovers...

Technically it is very possible as the melting temperature is really low compared to other metals and a brick can act as a mould.

However, apart from dealing with molten metal I was warned for really toxic gasses.

All in all it is possible, but not really worth it unless you're doing it mostly for fun .

The toxic fumes are Zinc Oxide from overheating the metal and can lead to "Zinc Chills". Anyone who has welded Galvanised metal will know the feeling.

[mrm]

Originally Posted by fstbttms

Anodes [...] are made of an alloy of metals and the best ones are made to miltary specifications[...]

MIL spec: http://www.wbdg.org/ccb/FEDMIL/a18001k.pdf

which seem to be along the lines of 'Zinc of technical grade purity'.

For some time already I considered making gypsum moulds for some more expensive / harder to get zincs.

[Orchidius]

All I needed at the time of doing the research were the regular brick anodes. They cost about 20-30€ here, and since the safety equipment to safely do it would cost a multitude of that it just wasn't worth it financially.

I'm not sure how much the anodes cost in SA and how much the safetygear will actually cost, but that's up to you.

[sailorchic34]

Just a note that in the US pennys made after 1982 are 97.5 percent zinc and 2.5 percent copper. There is a cheap source of zinc alloy.

[mrm]

Sadly, 2.5 percent copper is way over spec.

[sailorchic34]

Luckily the homemade zinc's does not have to comply with mil spec's, and should still work pretty well.

[mrm]

That is what I wanted to hear

Might be a way to get ones money worth.. out of money

[bornyesterday]

Originally Posted by perchance

The toxic fumes are Zinc Oxide from overheating the metal and can lead to "Zinc Chills". Anyone who has welded Galvanised metal will know the feeling.

+100%

As soon as a tiny whiff of smoke/gas hits your throat you will know that you never want to experience that choking, burning, suffocating feeling again. Your throat just yells at your brain, "Poison gas! RUN!"

That's when welding through galv. though. Lower temperature presumably used to cast zinc may make a difference - but please don't take the risk lightly.

[fstbttms]

Originally Posted by sailorchic34

Luckily the homemade zinc's does not have to comply with mil spec's, and should still work pretty well.

No offense, but on what do you base that statement?

[Efraim]

Originally Posted by mrm

Sadly, 2.5 percent copper is way over spec.

The result will not be 99.99 pur zinc or whatever millspec is, but the nobility of the zinc itself does not change, you'll just has a little less per volume.