• KwonP1 commented on ToolNut's instructable Electrolytic Rust Removal aka Magic1 week ago
    Electrolytic Rust Removal aka Magic

    No. It must be dc supply. Ac will pull rust off both rebar and the tool being cleaned

    I dont know why this instructable says baking soda isnt acceptable. I've removed rust off several parts using baking soda no problems. I used 2 tbsp per gallon of purified water, and repurposed a laptop charger to provide 19 volts dc at 3.42 amps. Electrodes were 0.090" steel sheets placed around the part. Exposed copper in the solution didnt cause problems, and took about 17 hours to complete. The part was covered with orange gunk that washed right off. The part needed immediate oil as the solution completely degreased it.

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  • KwonP1 commented on tranoxx's instructable Identify Metals4 months ago
    Identify Metals

    Its a very basic guide, and really only applies to metals in its pure form. Most scrapyard and commercial sources have an alloyed form of each material, meaning its mixed with other metals and some of its properties will change. Often times it may be washed with another, electroplated, chemical plated, hardened, etc. Not unusual for something that appears to be one metal is actually another- for example, gold and silver plated objects. Another example, pure tin may snap when bent, but the common 'tin sheet' is a steel sheet with a thin layer on tin on the surface, and it does not make noises when bent (with a brake). A few of my own methods- aluminum is diamagnetic (sp?). this means a non moving magnet will not stick, but a moving magnet the aluminum will gain some magnetic properties. Chrome is usually plated on to another metal, there is decorative that can tarnish, peel and flake off, if in good condition has a mirror finish, and is pretty soft. Then there is hard chrome often used on load bearing parts (axles, shafts, bearings, etc) that is matte silver in color, can be very glossy in texture, will not be scratched even with a hardened steel sample, generally does not tarnish or corrode. Its not just silver that turns black over time. the presence of ammonia in the vicinity of a metal can make it turn black. (learned this the hard way when i accidentally left steel tools in a bucket of water with some house paint in it) long term exposure to ammonia can cause pitting. Best way to identify if something is solid magnesium is its price tag. Its expensive. really expensive. alternatively, small metal filings (shave off with a steel knife) will readily ignite by match or lighter flame and burn bright white. primary consumer uses would be performance engine blocks and performance car wheels (rims). Titanium is a tough one to identify, but again easy if you just look at the price tag, the stuff is more than $1200 an ounce. Ti is rarely used in every day objects, exotic purposes only- medical, aeronautics, and high end camping gear. I have a Snow Peak camping set made of Ti, only way you'd know its Ti and not something else is that it will scratch ordinary steel utensils (plus its like 50 bucks a pot!)

    back in the old days (pre-1933) when gold coins were in circulation (and money was worth so much more) people would bite the coin and see if there is a small dent from the bite to determine if the gold coin is legit. Gold is very soft and can even rub off on your fingers. pure solid gold is rarely used for any practical purpose, it is mostly used for jewelry. general purpose gold is either white gold (alloyed) or gold plated electrical components. if you're trying to salvage gold from electrical components or connectors you'd need a few hundred pieces to get a few grams of gold- there really isn't that much gold when its plated on another material.

    it is likely tinned copper wire. this is copper wire coated with tin so it is easily soldered with other wires or electrical components. the tin is only a few ten thousandths (0.0001") of an inch thick. i know back in the 60s and 70s for house wiring (in walls or appliances) they'd use aluminum for conductors. it was cheaper at the time to use alumnium than copper, but when overloaded the wires are known to start fires and is banned in construction and general use today. it is unlikely alumnium would be used for cell chargers.

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