# What metal... yellow in AR?



## Duxthe1 (May 5, 2022)

I had a decent collection of fuel level senders that had a ceramic circuit board as part sender with an unknown metal deposited on said board. I gave them a HCL bath to clear the solder and then proceeded to digest the precious metal off the boards. I was expecting pd (just a guess) but the solution has a very bright clear yellow color. No real hint of orange or red. The solution is not very saturated but the stannous test turns orange-ish but fades pretty faint. Can anybody give me an idea of what I have in solution based on this description?


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## eaglekeeper (May 5, 2022)

I have done a few of those in the past and the ones I had were Pt. With out a picture of the stannous test it's hard to be 100%, But the description of your testing appears to be Pt.


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## Lino1406 (May 6, 2022)

Stannous test fading - no, or very, very little precious metal


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## Duxthe1 (May 6, 2022)

After boiling down the solution, it remains yellow and the stannous test shows a orange/peach color.


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## Stibnut (May 6, 2022)

If the stannous test is no longer fading, you could have some Pt in solution. Not very much, or the solution would be an orange or red color. The solution could also be yellow due to several base metals of which ferric iron is the most likely.


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## Duxthe1 (May 6, 2022)

I wouldn't expect iron from these ceramic circuit boards. I'm familiar with FeCl and its not that muddy yellow, but a bright clear yellow. I did a heated HCL prep to get the solder off the boards and would have expected any iron to be pulled out at the same time. That wash ended up green/grey. These boards also had carbon traces that were the resistive element for the sender. Is it possible that the carbon is being involved in some way? 

I'm leaning towards just treating it like Pt since that seems to be the consensus, but feel free to keep kicking any ideas my way in the meantime. Many thanks.


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