"Baby Plater," and CDM (Current Density Meter)
LOL!! No, we don't plate baby shoes. What I meant by "baby plater" is that we're rookies. We're hobbyist platers who are just learning how to plate. We're having some great successes, but also some "failures."
Regarding the CDM, I cannot tell you how it works, but I can tell you what it does. A CDM can calculate the total surface area, in square inches [I think they generally calculate in square feet, and then you convert] of the cathodes that you're plating.
As you probably know, it is crucial to know the surface area of the item that you're plating. In our case, we're plating leaves (from trees). For instance, yesterday, as a test, we plated a Silver Maple leaf. We gave it a base plating of copper, and then we plated over that with Nickel.
Well, before plating, we first have to calculate the surface area of the leaf, so that we'll know how to set the amperage. The rule of thumb we learned is 1/10th amp per square inches of cathode, in copper plating [or electroforming, as it's called]. Some say 1/16th.
Anyway, the way we currently calculate surface area is by actually placing the leaf down on 10/10 graph paper, and tracing its outline. Then we count the complete squares, on the graph paper, within the outline. Then we count those squares along the edges that are more than half full [using Caswell's approximation that we recently read at the end of their book], and add that to the figure we got for the total number of complete squares.
So, if we count 306 squares [both sides of the leaf], then the surface area of the leaf is 3.06 square inches [there are 100 squares per square inch on 10/10 graph paper]. Then we multiply that by 1/10, to get about 0.3 amps, and that's what we'd set the amperage to.
Now, if you're plating 20 leaves at a time [which is what we do, because we have a long tank, and need to plate at a "production" level], it can be a real pain in the behind to count squares on graph paper for 20 leaves [even though, after a while, you'll accumulate enough tracings where you can simply search for a tracing that comes close to matching any new leaf you're going to plate].
With the CDM meter, you don't have to count squares on graph paper. I don't know, yet, how it hooks up, because I haven't got my hands on one yet. But all you do is hook it up, put your cathodes into the bath, and read the amps on the meter instantly--no counting needed.
For us, a CDM is going to be crucial, because leaves, cones, flowers, etc., have "odd" shapes. It can be a real pain to trace some of these leaves. It's not an efficient use of time. Preserving the leaf; sealing the leaf to protect it from the acid in the bath; gluing the jewelry finding on it, and all that stuff takes enough time without the additional time of having to count squares on graph paper for each leaf.
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03-16-2005, 10:14 PM
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