We’ve been manufacturing sacrificial aluminum and zinc anodes since 1992—supplying dependable corrosion protection to fishermen, distributors, and marinas.
At Purity Casting Alloys Ltd., we produce a wide range of crab trap anodes from 0.5 lbs to 5 lbs, designed to perform in tough marine environments. Our long-standing success comes down to three things: consistent quality, reliable availability, and the ability to deliver custom sizes when you need them.
With an on-site analysis lab, we verify every batch to ensure alloy consistency from anode to anode—so you know exactly what you’re getting, every time.
Our aluminum anodes meet MIL-A-24779 specifications, and our zinc anodes meet MIL-A-18001K. We also offer a variety of core materials to match your specific application requirements.
Whether you’re outfitting crab traps, fishing vessels, or larger ocean-going equipment, we provide cost-effective cathodic protection you can count on—built right here in Canada.
Zinc vs. Aluminum
What's The Difference?
Zinc (MIL-A-18001K)
Zinc is the ideal sacrificial anode when a vessel is docked or anchored in seawater for extended periods.
Unlike other metals, zinc is better at shedding film buildup, continuously exposing fresh zinc to the water and keeping the anode electrochemically active. Aluminum anodes, in contrast, can develop a crust that passivates the anode, making it less effective.
The longer a vessel sits idle, the greater the risk of anode passivation. However, when the vessel is moving, the water flow helps clean off the oxide layer and reactivate the anode, regardless of the metal type.
For vessels that are regularly active in saltwater, both zinc and aluminum anodes work well. But if a boat remains stationary for extended periods in saltwater, zinc anodes are the better choice.
Aluminum (MIL-A-24779)
The Advantages of Aluminum Anodes
Many manufacturers and boaters prefer aluminum anodes over zinc or magnesium for several reasons.
Aluminum has become more affordable in recent years, making it a popular choice for installing sacrificial anodes on vessels, engines, and other equipment.
Aluminum anodes protect effectively in saltwater, perform better in upper brackish water, and decently in freshwater, but they tend to develop an oxide coating (passivation) faster than zinc. Regular cleaning prevents this, ensuring aluminum anodes remain effective.
EPA reports indicate that magnesium and aluminum anodes are more environmentally friendly than zinc, though the environmental impact of zinc is minimal.
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