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Bene505 02-06-2009 10:48 AM

Other uses for zinc
 
When looking at a bunch of sailboats while shopping for ours, I noticed that the majority of older boats had rusty keel bolts. One actually had the top layers of the keel bolts flaking off, like beer bottle cap that were gingerly placed back on top. To prevent this, why don't we fasten a small zinc to each of out keel bolts?

The other thing I noticed were engine mounts. The engine mounts on older boats were usually rusty, which meant for a costly repair. Why don't we fasten a small peice of zinc to each engine mount? It would protect the mount and possibly the engine as well.

And I have to believe that the zincs used for such local applications would last a long time.

So there you have my question, why don't we use more zincs in more places?

LittleMissMagic 02-06-2009 11:27 AM

Simple answer is this.
Zincs stop electrolysis, which occurs in the water. Once you remove a piece of metal from the electrolyte, (usually salt water in a boats case) you stop the process.
The corrosion issues you described above are caused by oxidation, so you would have to remove the oxygen from contact with the metal.
This is done on the atomic level by using the galvanizing process or stainless steel.
Hope this answers your question.

LittleMissMagic 02-06-2009 11:33 AM

Quote:

Originally Posted by LittleMissMagic (Post 444228)
Simple answer is this.
Zincs stop electrolysis,

Let me rephrase that. Zinc, (or any type of anode) does not stop electrolysis. It merely adds a less nobel metal to the circuit for electrons to attack, reducing damage to the components you are trying to protect.:)

Bene505 02-06-2009 11:45 AM

So if your keel bolts are sitting in water, use zinc. If they are dry, paint them.

Is that what you mean?

sailhog 02-06-2009 11:57 AM

Bene,
I think that zinc will protect more noble metals from galvanic corrosion when suspended in seawater, but not from oxidation.

bubb2 02-06-2009 12:47 PM

http://www.crcindustries.com/faxdocs/TCHDTA/130.pdf

http://images.westmarine.com/thumb/279646.jpg

This is what you need to use on those keel bolts. wire brush any rust off and paint.

sailaway21 02-06-2009 01:01 PM

Zinc anodes depend upon a medium such as water to carry the electrical charge, most commonly in the areas of turbulence around the rudder and shaft. The charged water treats the zinc and the steel as one homogenous substance resulting in the zinc's erosion. It's not the zinc's attachment to the steel that does the job as much as it is it's proximity to the flowing water which imparts a difference in potential or current. That force is absent inside on the keep bolts. The effects are similar but the processes of corrosion are different. Were they similar, your car would come equipped with zinc's and my Green Goblin '97 Ford pick-'em up wouldn't look like a gunnery target.

You can use the product bubb2 lists above or you can just smear some grease on them. If you're picky about your grease, you can use silicone grease, allowing you to eat any french fries you drop on it.

TxLnghrn 02-07-2009 11:11 AM

Two quick Questions
 
Is this product for Stainless as well as Galvanized?
Grainger has it for $12 Amazon for $83. What am I missing here?

Power Tools & Metalworking > Lubricants > Corrosion Inhibitors > Zinc It,16 Oz : Grainger Industrial Supply
Amazon.com: CRC 18412 Zinc-It Instant Cold Galvanize, 13 Wt Oz: Automotive

bubb2 02-07-2009 11:17 AM

Quote:

Originally Posted by TxLnghrn (Post 444773)

Amazon has free shipping:D





Got to be a type O

LittleMissMagic 02-07-2009 11:17 AM

There is really no need to use it on stainless, since the chemical makeup of stainless already inhibits oxidation. As to why amazon is so proud of it, I haven't a clue. It looks like the same product, but that price is absurd.

I guess there are suckers out there.


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