Zinc Anodes

The various sized and shaped zinc anodes have to be changed yearly on a boat. In total each boat begins the year with approximately 50 lbs of zinc.

As an example I can purchase 1 lb zinc bars from Canada Metals at $1.00 lb,, the zinc once cast into an anode now is worth about $5.00 lb.



Zinc has a low melting point you could probably use RTV to make semi permanent moulds. Be a good sideline while scrap prices are down.


Zincs & Anodes | West Marine

Did some research in using RTV for zinc casting, it won't work the temperature of molten zinc is to high although suitable for pewter casting.

Would be best to make an aluminium mould or use sand casting.

To make an mould from aluminium yoju first need a pattern, for this we would purchase a new zinc anode. Now to make the mould we need to make a wooden box wide enough to slice in half giving us a top and bottom.

Examine the zinc anode for the parting line then fill the bottom box with modelling clay, using a spoon remove any clay surrounding the pattern down to the parting line. One half of the pattern should be exposed while the other half buried in clay.

I use an acorn nut for this next procedure, press some random dimples into the clay, put the top box onto the bottom then seal the box's were they join with clay. Spray on some mould release then pour in a filler of your choice. As a filler my choice is Bondo an auto body filler, but you can use plaster, recommended you paint the plaster once r removed and dried. The paint forms a hard skin on the outside of the plaster making it harder.

Smooth-on sells RTV rubbers in various hardness, they also sell the mould release.

If you decide to use the Smooth on products be sure to watch the videos on how to remove air bubbles.


After the filler used to fill the top half of the paired box's has cured, turn the box over then remove the clay and only the clay leaving your pattern on the cured filler. Once the box is free of modelling clay repeat as you did with the top box before, spray on some mould release the fill the box with filler and let it cure.

Next morning your box should be ready to open, remove the zinc pattern, use the mated cured pairs as patterns to cast your permanent zinc mould from aluminium, you will now see that the dimples you pressed in previously now have a male and female registrations with the two halves fitting perfectly.

Once you have cast these plaster patterns into aluminium copies you can hold them together using a C-clamp while you pour in the molten zinc.

Smooth-On, Inc. - Mold Making & Casting Materials Rubber, Plastic, Lifecasting, and More

The ladies on the forum might even get into casting, lets say you found a unique very old figurine that had been broken over the years with bits glued back on but the glue seams have darkened with age and become unsightly and unstable to handle.

Using the technique I described above on how to make a mould, were going to make a few changes and use only plaster but we have to leave a hole on the bottom same place as you observed from the original ceramic.

You may have to cut the hole in later.


Also the parting line on the original would have been sanded off before being glazed and fired so were going to estimate the parting line and this is the beauty of using modelling clay.

Do not forget to press the dimples into the clay as these become registration marks for the finished halves when they are paired together.

Once we have both plasters cured we can now use our freshly made mould to pour slip into the mould. Let the slip set a few minutes before pouring out the excess. Let the slip dry until it is safe to remove from the mould,

I believe the piece you removed from the mould is know called green ware, ready to glaze and fire in the kiln.

You never know the piece you started with may have been out of production for the past 100 years and you have resurrected a rare piece, having green ware available for family or friends who love doing pottery..

Using unique shapes from the toy department and RTV rubber to make moulds, you could make candles and soap or my favourite - chocolate.

Imagine your very own one of kind hollow chocolate Santa.

Originally Posted by alloy2

The ladies on the forum might even get into casting, lets say you found a unique very old figurine that had been broken over the years with bits glued back on but the glue seams have darkened with age and become unsightly and unstable to handle.

Using the technique I described above on how to make a mould, were going to make a few changes and use only plaster but we have to leave a hole on the bottom same place as you observed from the original ceramic.

You may have to cut the hole in later.


Also the parting line on the original would have been sanded off before being glazed and fired so were going to estimate the parting line and this is the beauty of using modelling clay.

Do not forget to press in the dimples.

Once we have both plasters cured we can now use our freshly made mould to pour slip into the mould. Let the slip set a few minutes before pouring out the excess. Let the slip dry until it is safe to remove from the mould,

I believe the piece you removed from the mould is know called green ware, ready to glaze and fire in the kiln.

You never know the piece you started with may have been out of production for the past 100 years and you have resurrected a rare piece..

If you ever wondered how they made those bronze figures hollow in the middle, the molten bronze is poured into the mould then allowed to cool long enough to form a skin before pouring out the excess metal. Once the work has been pulled from the one time use mould the pour hole on the figure is welded close.

The artist will use the excess bronze from this current project to maintain colour he/she make small brazing rod and a patch, once the patch has been brazed into place and cleaned up you would never know where the brazing took place unless you had the piece x-rayed.

Originally Posted by HT1

You found a simple truth: boat shops have a 200-500% markup. Why, if you can afford a boat you can and will pay, no choice no option. boating is either an absolute necessity or totally a recreational activity. in both cases you pay because you can or you have to


V/r HT1

The profit factor does not only apply to boat zinc's if you read a previous post I made to the casting forum where I had cast fishing weight moulds. I had turned scrap cast aluminium having a value of $0.70 lb. at the time of posting into a product having a value upwards $20.00 lb..

You don't have to be a genius to pull this off.

This below is some of my work.

http://www.scrapmetalforum.com/metal...ght-molds.html

Originally Posted by ChildhoodDream

Even tho I Live in the land o lakes, I have always been a landlubber,lol... Not afraid of the water or such as I can swim like a fish, but I prefer the dry land for my travels and adventures.

I have went down rivers and creeks on rafts and such. I enjoy fishing in a boat and such, but there are far more things that interest me that are on dry land.

The reason that I decided to post on this topic is that I didn't have a clue about the subject before I read over this thread. I tried looking up some information on these Zinc Anodes and from the little I read it seemed that these are only used in salt water, and not needed for the waters of the lakes of Minnesota?

Was curious about their use. I did read about the electrical charges and loss of metals and such and I have a understanding of those processes.

Can you give us landlubbers a short coarse on their uses and applications for our curiosity?

,Aluminium, Magnesium and Zinc all have uses as anodes in galvanic protection, I'm not well versed on this topic but will give it my best shot from what little I have learned over the years.

Hot water tanks used in industry or home have anode protection, to extend the life of the tank these should be replaced every couple of years. From my experience those anodes are made from either magnesium or aluminium.

Galvanised metal ware, specialised structural steel for example high tension power towers and chain link fencing has been dipped in molten zinc.

Zinc anodes used in concrete affixed to the re-bar, underground tanks and pipe lines.

So yes I would say your boat even if used in fresh water would benefit from the use of anodes, itis just that the galvanic reaction ( deterioration ) of the anode is not as obvious had the boat been in salt water.

When you have a galvanic reaction taking place you have the production of hydrogen, hydrogen causes embrittlement in metals which in the case of an aluminium boat may account for those cracks forming as the boat ages. Protect your investment install anodes, car, boat trailers that riding lawnmower you cherish.

If your boat is made from aluminium, the boat with out the more reactive zinc anode has become itself sacrificial.

That lawn mower sitting over long periods without use the aluminium piston and the iron block are having a love affair by exchanging electrons left long enough the piston becomes seized in the bore. A sacrificial zinc anode would have prevented this love affair.

If you live in an area that uses a lot of salt on the roads, use anode protection on your vehicle if your not planning to trade in your ride every couple of years anode protection regardless of slated road will prolong the life of your ride.

As consumers we're not taught how to prolong the lifespan of our purchases other than the money lenders encouraging us to borrow money for home improvements.

Galvanic Protection would be a lifetime study.

On a side note, it is a well known fact chrome plating causes hydrogen embrittlemnt, parts such as a tube front axle and leaf springs used on that T-Bucket roadster are now prone to forming cracks leading to failure.

Anodes used in concrete.
https://www.icri.org/publications/20...l.pdf#original

ChildhoodDream I would like to thank you for asking your question as it has inspired me to do further research.


This article is a good read.
Cathodic protection


Water main failure due to corrosion.
Cathodic Protection Management, Inc. - Services


Wow this article on zinc totally blew me away, this is a must read for everyone.
Top Ten Benefits of Zinc | Poliquin Article

Since this thread has a lot of mention on RTV rubbers, I thought it appropriate to continue with posting this SCUBA mould cast at my Home Foundry.

The picture below was a prop which I used in my ebay ads when listing this item for sale. The mould sold consistently at $19.99 having less than two pounds of aluminium to manufacture. The lead weight you see in the picture was actually cast using RTV then painted silver to have the appearance of lead.

When your going to pour lead into the mould it is best to coat the inside with a coating of soot, this makes removal of the cooled lead weight much easier.

The original mould used as a pattern was also a purchased item, to prepare it as a pattern just did some light sanding to remove imperfections left over from the original caster. By making the pattern smoother than received also made it easier to remove from the sand before casting.

Take close look at the SCUBA mould, looking down into the mould you will see that the sides all have a slight tapper. This tapper is called a relief for sand casting or permanent mould you need 3% to enable easy removal of the pattern.

If your using the lost wax method or lost foam you can produce castings with negative relief such as an aluminium cylinder head or engine block with a water jacket incorporated into the casting..