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Cleaning carts

Posted: Sun Nov 20, 2016 2:51 pm
by SpyAlelo
There are lots of misinformation in regards to how the edge contact on carts should be cleaned. I hope I can clear up some of that and how to reliably clean them up without causing permanent damage. But first, let's get two facts clear:

  • The contact pads on carts are made of copper, with an in-between layer of nickel and a top one of gold.
  • Gold does NOT rust/oxidize. It will tarnish, but will never oxidize.
With this in mind, the reasoning behind using gold as a top layer is not because it conducts better. Copper is much better at this, but the problem with copper is that it oxidizes. Silver would be the best conductor being superior to copper but it also suffers from oxidation. By using gold as a top layer on the contacts you prevent corrosion and allows you to have a long usable life of the edge connectors. The friction does get them dirty after all, so occasional cleaning is needed. Here are the things you should never do to clean a cart:

  • Never use commercial metal polishers such as Brasso or BlueMagic. They will remove the plating.
  • Forget about using sanding paper no matter how fine! The gold layer is only a few microns thick, you will remove it quite easily.
  • Any other polishing agents such as toothpaste. It may be safe for your mouth, but is not for electronics.
When you remove the top layer by using the methods above, you leave the nickel or copper exposed. Yes, your cart will work much better right away and will look silvery-shiny. But oxidation will eventually build up, and you will see yourself having to clean the cart far more often especially if you store the cart for some time. Cleaning a cart is far easier and gentle than most people think. All you need is:

  • A very mild solvent to remove oils or mild chemicals, such as isopropyl alcohol 91% (or higher). Alternatively, you can use distilled or deionized water.
  • A clean and soft cloth. Microfiber would be preferred. You can use a paper towel but be mindful of the paper leftovers.
  • A commercial contact cleaner for electronics such as DeoxIT ProGold Connector Enhancer from CAIG labs. If you can't afford it or just don't want to buy one, you can use a pencil rubber eraser instead to polish the pads.

All you have to do now is to clean the pads in an up and down motion (not sideways) with the cloth and isopropyl or distilled/deionized water, then apply your commercial electronics contact cleaner and wipe it off with a dry part of your cloth. Do not remove the film it leaves behind, is a special lubricant.

If you use the eraser rubber instead, do it in an up and down motion on each contact. Then clean the contacts again at the end with your mild solvent of choice.

Your cart is now squeaky clean and it should work for a very long time before having to clean it again.