After using Ox-Gard and other anti-oxidant compounds to protect wiring and electrical connections, it occurred to me that an anti-oxidant paste that was truly conductive would be of assistance when crimping copper wire to brass and copper terminals. It would be highly conductive, so that it would actually improve the electrical path on new metal connections, yet still prevent oxidation. I might have guessed that somebody invented it years ago. It's a copper colloidal anti-oxidant surface treatment, marketed by Thomas & Betts as Kopr-Shield ™ Colloidal Copper Surface Treatment. It's about as close as you can get to melted copper - if you could store it at room temperature in an ordinary plastic jar.
Recommend this product?
Kopr-Shield Compound is a homogenized paste containing 30-40% (by weight) of pure, polished colloidal copper powder, along with petroleum base oils and proprietary rust and corrosion inhibitors that simultaneously protect and lubricate, while enhancing the conductivity of the mating surfaces to which it is applied. Officially, this makes it a “electrically conductive, corrosion resistant compound” meeting the requirements of Sec. 200.6(A) of the 2002 NEC (National Electric Code) for Protection Against Corrosion.
Kopr-Shield is a rather sticky paste, yet will still flow into uneven contours and voids of crimped or clamped electrical connections. It appears to have been originally designed to prevent oxidation and enhance conductivity on electrical service items exposed to environmental extremes, such as outdoors conduit or cabling connections exposed to rain, salt air, and/or humidity.
The product has a temperature range in its paste form of -50 degrees F to +250 degrees F, and will not dry out or run at the extremes of this range. The manufacturer states that Kopr-Shield may be used to advantage in all types of electrical installations and will withstand temperatures of up to 1800 degrees F for short periods. Personally, I've never experienced that kind of extreme, nor would I ever ask that much of a product. One would think that at 1800 degrees, the Kopr-Shield would boil or run off long before reaching such a threshold, unless contained in a clamped fitting or crimped connector. For my own part, I have used it for applications involving copper, bronze, and brass connections, especially in connectors transmitting high current loads.
Usage and Experience
I’ve used Kopr-Shield to protect several copper-to-copper, copper-to-brass, and copper-to-bronze electrical connections, either screwed or clamp-style, as well as lug and terminals connectors crimped onto copper wiring (speaker cables, auto wiring, etc.) For this purpose, I dip the bared end of the insulated copper wire into Kopr-Shield before crimping the connector over it. It can also be used as a lubricant for aged fuse holders (clip-type) to ease fuse removal in older electronic equipment. And it improves the continuity and permanence of ground connections.
Because of its conductivity and tendency to fill small voids, Kopr-Shield actually increases the conductive surface contact area of mass-produced connectors that aren’t always a perfect fit. It also acts as an effective anti-seize compound for copper or copper-alloy components.
Connections that have been treated with Kopr-Shield show no additional resistance and no obvious signs of oxidation – interior copper surfaces coated with it do not even turn brown, let alone 'greenish’, and appear as-new.
More so than with other electronic sprays or compounds, Kopr-Shield must be used very sparingly. It is highly conductive, so it could form undesirable leakage paths for current and short out sensitive connections if applied too thickly. On the outside of the connection the conductivity of Kopr-Shield actually becomes a liability. On a crimped wire, using a protective nylon collar or heat-shrink shield provides additional insurance against the possibility of paste migration and formation of an undesired current path.
Kopr-Shield has proven to be a useful compound to improve the conductivity of small copper/brass screw or clamped connections, and prevent future oxidation (the green scourge). By the very nature of its pricey central ingredient, it is not cheap, but only a small amount is needed for most jobs (the 4 oz. jar is a sensible size for most homeowners). I highly recommend it.
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