Interesting ceramic discs on old boards. Silver and/or palladium perhaps?

[kurtak]

In this link - post 8 (down from top) Cap number 10 is an epoxy NON-polarized Ta Cap

https://goldrefiningforum.com/threads/tantalum-capacitor-scrap-purchasing-international.21530/
Edit to add; - the epoxy - non-polarized (number 10 post 8) Ta Caps are relatively common on more modern CBs

Kurt

 

[Alondro]

Those black SPRAGUE CAPs are NOT tantalum !!! --- Edit to add; - at least I don't believe they are

Why ?

Because Ta Caps are inherently polarized - meaning that the vast majority of Ta Caps have a positive & a negative lead

So - one why to identify Ta Caps - & something they have in common is that most all of them (if not all of them) is that the positive lead - & the positive lead ONLY is identified one way or another

one example - Tantalum Capacitor Polarity Markings

another example -

& some more examples

Note the bullet shape

Note the *** on one end

note the + sign the ring & *** all on one end

note the white bar & shaved end

Note the bar on one end - if they are "black" with NO bar they are NOT Ta Caps

red ring on one end

note the *** on one end

Most other (aluminum) polarized Caps are marked with BOTH the + (positive) & the - (negative) lead - or can be identified because they don't have the solid Ta pellet inside them (so crushing them with a pliers will identify them

There are non-polarized tantalum Caps but they are far more rare

Some examples ------

View attachment 49330

For what its worth

Kurt

I only have a small number of uncertain ones now. I'll just keep all those together and deal with them later. I've got no shortage of other stuff to process! 7 full tubs worth!

 

[Alondro]

Those black SPRAGUE CAPs are NOT tantalum !!! --- Edit to add; - at least I don't believe they are

Why ?

Because Ta Caps are inherently polarized - meaning that the vast majority of Ta Caps have a positive & a negative lead

So - one why to identify Ta Caps - & something they have in common is that most all of them (if not all of them) is that the positive lead - & the positive lead ONLY is identified one way or another

one example - Tantalum Capacitor Polarity Markings

another example -

& some more examples

Note the bullet shape

Note the *** on one end

note the + sign the ring & *** all on one end

note the white bar & shaved end

Note the bar on one end - if they are "black" with NO bar they are NOT Ta Caps

red ring on one end

note the *** on one end

Most other (aluminum) polarized Caps are marked with BOTH the + (positive) & the - (negative) lead - or can be identified because they don't have the solid Ta pellet inside them (so crushing them with a pliers will identify them

There are non-polarized tantalum Caps but they are far more rare

Some examples ------

View attachment 49330

For what its worth

Kurt

Oh, and the little brown caps with the black powder inside packed around an aluminum plate will also be kept by themselves. I opened another very carefully, and found that it has nice little blob of the powder packed in tightly in the curled aluminum electrode, with the other electrode on the back side of the powder blob. So clearly the black powder is the primary capacitance material, which makes it very interesting indeed. I'll eventually do a dissolve since this black powder dissolves in HCl, then go down a reaction series, starting with copper, to see what base metal the black metal powder cements out on. That will help me narrow down its identity. It will also let me get it to a fairly pure state with the aluminum gone, then maybe I can find someone with an XRAF gun and get a complete identity.

 

[orvi]

Those black SPRAGUE CAPs are NOT tantalum !!! --- Edit to add; - at least I don't believe they are

Why ?

Because Ta Caps are inherently polarized - meaning that the vast majority of Ta Caps have a positive & a negative lead

So - one why to identify Ta Caps - & something they have in common is that most all of them (if not all of them) is that the positive lead - & the positive lead ONLY is identified one way or another

It will help a lot if we had a good picture of them, but of course, they do not need to be tantalums - cannot judge from the photo and be 100% sure. Just that marking style and brand - I am familiar with them as being tantalums. But you got a good point about polarity. Now I am uncertain about it

 

[kurtak]

I have a bunch of these old industrial boards. There are HUNDREDS of these discs, which I'm assuming are capacitors given how they're all in circuits with resistors

Alondro

I am going to make an attempt at helping you out here

Although it is true that CBs (circuit boards) have PMs (precious metals) in them - you need to understand that recovery &/or refining of those PMs is not - & in fact MOST times is NOT worth the cost of going after them & in fact will cost you WAY MORE then what you can/will recover --- & I am not talking about just the cost of time & money to recover/refine those PMs - but also the cost of creating LARGE amounts of VERY TOXIC waste which is a whole other cost in having to deal with that toxic waste in order to PROPERLY dispose of that toxic waste

Granted - there are some things on CBs that are well worth going after such as IC chips, gold plated fingers off RAM & finger cards, "fully" gold plated pins, old ceramic CPUs & a few other things (but VERY few other things) that are actually worth chasing - but even then - for it to be worth while you really need to have relatively large amounts of that stuff to really be worth while

Outside of that MOST other things you find on CBs (with a few - but VERY few exceptions) simply are not worth chasing & that is because it will cost you WAY MORE then you can/will recover - even if your time is free

Per the bold print in the above quote - at the moment you seem really focused on the ceramic disc type Caps because you have heard/read that they have PMs in them- which though may be true (but not always true) the real question is --- is it worth while going after those PMs ???

My answer to that is --- NO - they are absolutely NOT worth going after & that is because going after the PMs in them is going to cost you WAY MORE then you can &/or will ever get out of the --- even if your time is free

To put it in perspective - I want you to watch this video - in which the guy recovers some silver from some disc type ceramic Caps --- then I am going to tell you why it is going to cost you WAY MORE to recover that silver then what the silver is worth

https://www.bing.com/videos/search?...VDRE&msclkid=1504e274b33411ec92757e461a31238c
In this video - he processes 3 different types of ceramic disc Caps - blue - tan/brown - & yellow

Blue = 175 grams of Caps

Tan/brown = 97 grams Caps

Yellow = 93 grams Caps

Please note how many Caps it takes to make up those numbers

Now then - in that video he also shows how much silver he got from each type Cap - which was -----

Blue = .4 gram silver --- tan/brown =.8 silver - yellow =.5 gram silver

at the current price of silver ($24.61) = 79 cents per gram (.79)

it takes 454 grams to make a pound - so if you do the math on what you would recover from a pound of each type Cap is as follows --------

Blue = 1.03 gram/Ag X .79 = 81 cents per pound

Tan/brown = 3.74 grams/Ag X .79 = $2.95 per pound

Yellow = 2.93 grams/Ag X .79 = $1.94 per pound

Now then - lets talk about how much it is going cost - just in the cost of nitric to process a pound of those ceramic disc Caps

In order to leach the silver from the Caps you need to cover them with nitric/water (distilled water)

There needs to be enough nitric to dissolve not just the silver but also the base metals - and the acid needs to be strong enough to do its work

So - you will need "at least" one liter (or more) of nitric/water

Using 67 - 70% nitric you will want to use "about" 300 ml acid (or more) & 700 ml water to insure (1) there is enough acid to leach both the silver & base metals & (2) be strong enough to actually do the job of leaching (even with heat)

Now if you buy nitric from Duda Diesel (one of the cheapest places to buy nitric) you will pay $100 for 2.5 liters of 67 - 70% nitric --- which means $2.50 per 100 ml X 3 = $7.50 (that does not include shipping cost)

So ------------

Blue Caps/pound = $7.50 for nitric - $.81 (81 cents) silver recovered = it just cost you $6.69 to recover 1.02 grams silver

Tan/brown Caps/pound = $7.50 for nitric - $2.95 silver recovered = it just cost you $4.55 to recover 3.74 grams silver

Yellow Caps/pound = $7.50 for nitric - $1.94 silver recovered = it just cost you $5.56 to recover 2.46 grams silver

To put it a bit more in perspective - in order to recover one troy ounce of silver from these Caps - you would need ---------

Blue Caps = 31 pounds of Caps --- Tan/brown Caps = 8.34 pounds of Caps --- Yellow Caps = 12.68 pounds of Caps

Then - you never get spot price when you go to sell your metal - so you actually see even less out of your effort/cost

Examples; - if you sell direct to a refinery you will only get 93 - 95% spot - BUT - to get that you need to have a minimum of 500 ozt --- so even if you have that 500 ozt you still have another 5 -7% loss on you efforts & so that 5 - 7% is added to your cost

If you sell direct to a refinery - but have less then 500 ozt they are only going to pay you 80 - 85% spot - so even more lost in your effort & more cost added to your recovery

Then - if you sell to someone other then a refinery you may - or not (depending on the buyer) take another hit on that spot price - so another hit on your cost

Then - there is still the cost of cleaning up all the toxic waste you will be creating - that to has a real cost because you will have to pay for more chemicals to clean that waste up for "proper" disposal

Time - it/s one thing to spend your time (& money) on something that breaks even &/or even makes a couple buck - but when the cost (money) is more then the recovery - then it is also costing you time - which in turn means you are spending both time & money

And spending time & money to do what ????

Answer = spending both time & money to create toxic waste !!!!

For what it is worth

Kurt

 

[Alondro]

Alondro

I am going to make an attempt at helping you out here

Although it is true that CBs (circuit boards) have PMs (precious metals) in them - you need to understand that recovery &/or refining of those PMs is not - & in fact MOST times is NOT worth the cost of going after them & in fact will cost you WAY MORE then what you can/will recover --- & I am not talking about just the cost of time & money to recover/refine those PMs - but also the cost of creating LARGE amounts of VERY TOXIC waste which is a whole other cost in having to deal with that toxic waste in order to PROPERLY dispose of that toxic waste

Granted - there are some things on CBs that are well worth going after such as IC chips, gold plated fingers off RAM & finger cards, "fully" gold plated pins, old ceramic CPUs & a few other things (but VERY few other things) that are actually worth chasing - but even then - for it to be worth while you really need to have relatively large amounts of that stuff to really be worth while

Outside of that MOST other things you find on CBs (with a few - but VERY few exceptions) simply are not worth chasing & that is because it will cost you WAY MORE then you can/will recover - even if your time is free

Per the bold print in the above quote - at the moment you seem really focused on the ceramic disc type Caps because you have heard/read that they have PMs in them- which though may be true (but not always true) the real question is --- is it worth while going after those PMs ???

My answer to that is --- NO - they are absolutely NOT worth going after & that is because going after the PMs in them is going to cost you WAY MORE then you can &/or will ever get out of the --- even if your time is free

To put it in perspective - I want you to watch this video - in which the guy recovers some silver from some disc type ceramic Caps --- then I am going to tell you why it is going to cost you WAY MORE to recover that silver then what the silver is worth

https://www.bing.com/videos/search?...VDRE&msclkid=1504e274b33411ec92757e461a31238c
In this video - he processes 3 different types of ceramic disc Caps - blue - tan/brown - & yellow

Blue = 175 grams of Caps

Tan/brown = 97 grams Caps

Yellow = 93 grams Caps

Please note how many Caps it takes to make up those numbers

Now then - in that video he also shows how much silver he got from each type Cap - which was -----

Blue = .4 gram silver --- tan/brown =.8 silver - yellow =.5 gram silver

at the current price of silver ($24.61) = 79 cents per gram (.79)

it takes 454 grams to make a pound - so if you do the math on what you would recover from a pound of each type Cap is as follows --------

Blue = 1.03 gram/Ag X .79 = 81 cents per pound

Tan/brown = 3.74 grams/Ag X .79 = $2.95 per pound

Yellow = 2.93 grams/Ag X .79 = $1.94 per pound

Now then - lets talk about how much it is going cost - just in the cost of nitric to process a pound of those ceramic disc Caps

In order to leach the silver from the Caps you need to cover them with nitric/water (distilled water)

There needs to be enough nitric to dissolve not just the silver but also the base metals - and the acid needs to be strong enough to do its work

So - you will need "at least" one liter (or more) of nitric/water

Using 67 - 70% nitric you will want to use "about" 300 ml acid (or more) & 700 ml water to insure (1) there is enough acid to leach both the silver & base metals & (2) be strong enough to actually do the job of leaching (even with heat)

Now if you buy nitric from Duda Diesel (one of the cheapest places to buy nitric) you will pay $100 for 2.5 liters of 67 - 70% nitric --- which means $2.50 per 100 ml X 3 = $7.50 (that does not include shipping cost)

So ------------

Blue Caps/pound = $7.50 for nitric - $.81 (81 cents) silver recovered = it just cost you $6.69 to recover 1.02 grams silver

Tan/brown Caps/pound = $7.50 for nitric - $2.95 silver recovered = it just cost you $4.55 to recover 3.74 grams silver

Yellow Caps/pound = $7.50 for nitric - $1.94 silver recovered = it just cost you $5.56 to recover 2.46 grams silver

To put it a bit more in perspective - in order to recover one troy ounce of silver from these Caps - you would need ---------

Blue Caps = 31 pounds of Caps --- Tan/brown Caps = 8.34 pounds of Caps --- Yellow Caps = 12.68 pounds of Caps

Then - you never get spot price when you go to sell your metal - so you actually see even less out of your effort/cost

Examples; - if you sell direct to a refinery you will only get 93 - 95% spot - BUT - to get that you need to have a minimum of 500 ozt --- so even if you have that 500 ozt you still have another 5 -7% loss on you efforts & so that 5 - 7% is added to your cost

If you sell direct to a refinery - but have less then 500 ozt they are only going to pay you 80 - 85% spot - so even more lost in your effort & more cost added to your recovery

Then - if you sell to someone other then a refinery you may - or not (depending on the buyer) take another hit on that spot price - so another hit on your cost

Then - there is still the cost of cleaning up all the toxic waste you will be creating - that to has a real cost because you will have to pay for more chemicals to clean that waste up for "proper" disposal

Time - it/s one thing to spend your time (& money) on something that breaks even &/or even makes a couple buck - but when the cost (money) is more then the recovery - then it is also costing you time - which in turn means you are spending both time & money

And spending time & money to do what ????

Answer = spending both time & money to create toxic waste !!!!

For what it is worth

Kurt

Well, like I said, I do assays on just one or two pieces of a mystery component at a time, to determine what's in each type I have a lot of. There are 3 other types of cylindrical caps on those boards. One I've determined is just aluminum, but another poly Sprague type might be more interesting. Here's a pick of the exact type I found: https://images.reverb.com/image/upl...90,w_620/v1472609614/b1xogozwldmlmrr4bsku.jpg

They're INCREDIBLY expensive! I found a lot on Ebay of just 5 that sold for $24, and a single pair on that reverb site sold for $20. I might just try and remove them very carefully from the boards and sell them as used capacitors!

Per the yellow types, it certainly looks like I'm getting palladium. My stannous test (important to totally de-nitrify the solution or it won't work right) is showing the presence of it, and so I'll be buying dimethylgloxime for the secondary confirmation, and then processing the full batch.

I can also buy my acids locally; there's a place that manufactures them only half an hour from me, at pretty good prices. I'm paying about half what it seems most people are paying, and no shipping costs.

I use sulfuric because it can dissolve 2 moles of monovalent metal cations per volume vs 1 for the other acids (already cutting the volume required in half), and I'm very good at handling sulfate-based chemistry. Nitric, I only use that for the initial tests and the fine refining steps of silver and eventually for palladium, and for AR to dissolve Pt when I have enough of it to process efficiently.

I'm currently beginning my step-wise protocols I spent MONTHS researching and testing on gram-sized amounts on the first large batch of gold fingers. I'll be documenting the results. The protocol is based on reusing acid until it's totally saturated with metals, in a step-wise fashion which takes advantage of the differences in electronegativities and salt solubilities to keep kicking PMs out of solution while eating up more base metals, then displacing those in series for maximum recovery of as many metals as possible. In my first complete recovery experiment, I ended up with a solution of mostly iron and aluminum salts, which dried out in my little green house (in summer it hits 150F in there!) and dried into a little cake of material, which I can roast in a wood-fired kiln and glassify with the vast quantities of sand in my backyard.

At the end of this protocol, when applied to more complex components, I should end up with two crude types of PM powder (Au-Pt and Ag-Pd) which can then be refined very efficiently, as there will likely be less than 5% base metal remaining in it based upon my initial experiments. (Sreetips' videos have helped tremendously with with the protocol, even though I'm not aiming for the super-fine level of refining he does).

I also have a setup I've been working on to pull base metals from the waste with high efficiency. I discovered that turning the waste into a sort of battery cell with iron and copper electrodes connected to each other caused the creation of a steady internal voltage gradient in an anionic composition roughly 95-97% chloride salt to 3% or so nitric salts and a pH of between 1 and 2, and resulted in almost everything above iron on the reactivity scale reducing out of solution when I hit a critical concentration threshold: take the initial saturated waste and dilute in water, with 2 volumes of water for every 1 volume of waste soln. The electrochemical reactions took place incredibly rapidly as well, displacing all the heavy metals with iron in a single night. Copper crystalized out first, and interestingly Cu also reduced on the bottom of the copper electrode as very thick, highly pure crystals, suggesting the solution settles into a salt gradient from top to bottom which alters the current flow in differing portions of the electrodes. This could be a result of the weak voltage throughout the solution varying in intensity, causing the various metal cations to migrate into layers, which would feedback and intensify the voltage gradient as the salt gradient simultaneously, thus making the reduction reactions move faster and faster until all reactants were depleted. Studying research on liquid electrolyte batteries, such as vanadium cells, might give a proper explanation of this phenomenon.

This might be the hint that there's self-contained method of base metal purification that requires NO EXTERNAL ELECTRICAL SOURCE and nothing more than container and electrode geometry which is conducive for the self-generating electrolyte gradients! Given the speed of this reaction, it could prove to be the most cost, time, and resource-efficient method possible, at least for recovering copper.

The other metals then cemented out, and formed a black crust over the iron once the copper was mostly out of solution, additionally forming complexes of various types that settled out as grey ooze. The solution remaining was a very pale yellow-green (mostly iron chloride). I should make a documentary of this process. I've run it 3 times now, and it keeps working very well each time.

From there, almost everything left can be displaced with waste aluminum foil, by which time the pH has risen to the point where the reaction is no longer violent. These reactions appear to require very little input. I can just set them up and let them run, while doing other things.

Just as with the recent discovery of the iron phosphate battery, I believe we have been missing the BEST solutions to problems for a long time.

I don't jump straight into things full-blast, which is the mistake even most scientists make. Little by little, I study and refine every protocol until I've perfected them. I always ask myself a single question: ARE WE CERTAIN OF THIS? Doubt and questioning are essential for advancing techniques.

The biggest problem I've seen is that we often don't have very explicit protocols for recoveries with ALL details, including explicit measurements, molar ratios, temperatures, and masses/volumes of reagents listed. Those factors are absolutely vital for chemistry to work efficiently. In many PM recoveries I see large excess volumes of acids used, and it's really not necessary. I used to work in a research lab, and PROTOCOLS are the single most important part of any process. A few changes here and there DRASTICALLY change the outcomes, and streamlining the protocols can reduce waste astonishingly. For one biological staining protocol, I cut the use of solvents by 65%, while getting far better staining results by doing nothing more than changing the orientation of the slides, laying them on a flat staining platform instead of vertical. In another, I was able perform RNA in-situ hybridization on tissue sections even manufacturers of the kit couldn't get it to work on, simply by replacing one antigen retrieval step with an old tissue prep method from the 1940's everyone had forgotten about because it destroys DNA, but they had overlooked the fact that it does nothing to RNA and swiftly decalcifies bone. I got a chapter in a book with that protocol in 2020 (Methods in Molecular Biology: Chondrocytes) Sometimes its just the simplest things that get overlooked, especially when the procedures are complex.

I can point to a method I only found a few days ago for recovering PGMs from powdered catalytic converters using 60% sulfuric and 0.1M NaCl heated to 125C in regular atmosphere, resulting in highly soluble PGM chloride complexes, which were then easily reduced back to the metals. The chemists who discovered it tested many different concentrations, combinations and conditions before arriving at this highly refined protocol, which maximized recovery at nearly 100%.

I sound excited, because that's how I stoke myself up to force myself into doing these meticulous and painstaking tests. Otherwise... proper science is mind-numbingly boring and tedious! The RESULTS are cool, but it takes a very long time to get there.

As for time, heh heh heh, I lived my first 45 years with such extraordinary efficiency that now I can afford to play around in my little garage lab as much as I please. I planned LONG ahead of time for multiple contingencies and outcomes, and this forethought kept me prepared for all difficulties along the way. Some days, I just hike 20 miles for the heck of it because it's really nice outside. TRUE FREEDOM!

 

[kurtak]

Here's a pick of the exact type I found: https://images.reverb.com/image/upl...90,w_620/v1472609614/b1xogozwldmlmrr4bsku.jpg

That may be an (old) tantalum Caps --- the positive lead/side of the Cap being identified (edit to add; - as described in my other post) by the red strip on the left side/end of the Cap

Edit to add; - just guessing here but it looks like it may be an "early" version of the "bullet" shaped Ta Caps I post a pick of

Kurt

 

[kurtak]

They're INCREDIBLY expensive! I found a lot on Ebay of just 5 that sold for $24, and a single pair on that reverb site sold for $20. I might just try and remove them very carefully from the boards and sell them as used capacitors!

In addition to my last post --------

IF (the BIG IF) thy are Ta Caps that would in part explain their high price

Also - there are people out there that are into collecting - building - re-building &/or refurbishing OLD electronics - so they sell &/or buy OLD components/parts for their (above) hobby

Prices can run high for some of those OLD components/parts as they are sometimes rare &/or hard to come by

My point being that a high price/value does not necessarily mean/indicate PMs exist

Rarity/collector value (without PMs) can be a driver of high price/values

I suspect that is the case with these Caps

Kurt

 

[kurtak]

Per the yellow types, it certainly looks like I'm getting palladium. My stannous test (important to totally de-nitrify the solution or it won't work right) is showing the presence of it,

Per the bold print - not really true

If you have PMs in solution - & your stannous is good - you will always get a positive result for the PMs in solution

However - what can happen - is that if there is "free oxidize" (nitric, chlorine, etc.) in solution it can cause your "positive" test result to "fade" away - but it takes time

How much time it takes for that positive result to fade away can/will depend on a couple things

1) how much oxidizer will determine the time factor for the fading away

2) the manner/way you do your test ----------

If you do your stannous test in a spot plate - with "several" ml of solution - & you have "a lot" of oxidizer - the positive result can fade away quite quick --- that is the result of the metal - precipitated by the stannous - being re-dissolved by the oxidize --- & it can happen in a spot plate test relatively quick because you are using "several" ml of solution (with oxidize) so you have more oxidizer ions to re-dissolve the test result --- one of the reasons I don't care for doing my stannous testing in a spot plate

However - if you wet the end of a Q-tip - or put just "a drop" of solution on a paper (towel or filter) & then add just "a drop" of stannous - & there are PMs in the solution - you will get your positive result - AND - that result will take MUCH longer to fade away

That is because you are using MUCH less solution for the test - so there is MUCH less oxidizer to re-dissolve the test result - AND - the solution is spread out over a larger surface area (cotton Q-tip fibers &/or paper fibers) thereby giving the free oxidizer less opportunity to re-dissolve the test result

Doing a stannous test this way (if there is free oxidize) can/will take anywhere from an hour to several hours for the positive test result to fade away --- which is why I always recommend &/or ask people to do their stannous test this way when posting a pic of their stannous test

There is actually another reason for doing your stannous test this way instead of doing it in a spot plate - which I don't have time to explain right now

That all said - how are you doing your stannous test Alondro ?

And - can you please provide some pics of your stannous tests of the solutions you suspect to have Pd

Kurt

 

[Alondro]

Per the bold print - not really true

If you have PMs in solution - & your stannous is good - you will always get a positive result for the PMs in solution

However - what can happen - is that if there is "free oxidize" (nitric, chlorine, etc.) in solution it can cause your "positive" test result to "fade" away - but it takes time

How much time it takes for that positive result to fade away can/will depend on a couple things

1) how much oxidizer will determine the time factor for the fading away

2) the manner/way you do your test ----------

If you do your stannous test in a spot plate - with "several" ml of solution - & you have "a lot" of oxidizer - the positive result can fade away quite quick --- that is the result of the metal - precipitated by the stannous - being re-dissolved by the oxidize --- & it can happen in a spot plate test relatively quick because you are using "several" ml of solution (with oxidize) so you have more oxidizer ions to re-dissolve the test result --- one of the reasons I don't care for doing my stannous testing in a spot plate

However - if you wet the end of a Q-tip - or put just "a drop" of solution on a paper (towel or filter) & then add just "a drop" of stannous - & there are PMs in the solution - you will get your positive result - AND - that result will take MUCH longer to fade away

That is because you are using MUCH less solution for the test - so there is MUCH less oxidizer to re-dissolve the test result - AND - the solution is spread out over a larger surface area (cotton Q-tip fibers &/or paper fibers) thereby giving the free oxidizer less opportunity to re-dissolve the test result

Doing a stannous test this way (if there is free oxidize) can/will take anywhere from an hour to several hours for the positive test result to fade away --- which is why I always recommend &/or ask people to do their stannous test this way when posting a pic of their stannous test

There is actually another reason for doing your stannous test this way instead of doing it in a spot plate - which I don't have time to explain right now

That all said - how are you doing your stannous test Alondro ?

And - can you please provide some pics of your stannous tests of the solutions you suspect to have Pd

Kurt

The nitric solution no longer tests positive, and it has turned very deep violet-color in the tube with the ceramic disk fragments in it. Whatever other metal is in the ceramic disk (manganese?) appears to have swapped with it, and the surface of the ceramic turned from beige to orange.

In the HCl test tube, the possible palladium eventually fell off the fragments of ceramic and is at the bottom of the tube as dark grey, heavy powder that settles out in seconds even after vigorous swirling. I can wash that little bit and then dissolve it in nitric, since it should have nothing else now to displace it.

I do my stannous tests as drops on paper. The only fade I've ever encountered was with Pd tests. Gold has always been very reliable. Haven't done Pt-containing solutions yet. The only material I have that might contain some is a few old jewelry bits, but I have too little to bother with for now.

I do have a pair of nose-piece mounts from a broken pair of REALLY old gold-rimmed glasses . I wonder if they're iridium, as I can't get them to dissolve in ANYTHING! I even tossed them in a little hot AR, and NOTHING happened! They just sat there and came out as shiny as when they went in.

 

[Alondro]

That may be an (old) tantalum Caps --- the positive lead/side of the Cap being identified (edit to add; - as described in my other post) by the red strip on the left side/end of the Cap

Edit to add; - just guessing here but it looks like it may be an "early" version of the "bullet" shaped Ta Caps I post a pick of

Kurt

Yeah, these parts are so old, it's really been tough to find pics of the exact models elsewhere. The black ones are called 'Black Beauty' types by buyers on Ebay. They're much lighter than the beige ones. Even the biggest (substantially larger than the beige ones) tops out at 5 grams, while the beige ones are 6 grams. Breaking one open reveals what looks like just an aluminum foil core. They're bought for old electric guitar equipment, about $1-$3 apiece depending on the exact type, BUT they need to be tested first. They're also tough to remove with the leads intact because it's a soft copper core which crushes and breaks easy when tugged, and the ends on the other side of the board are squashed flat so they don't pull out nicely even when you melt the solder.

Now, the gold-legged transistors, those are nice! And they come out easily and intact (nickel-iron or steel leads plated with gold). If I can find someone with electronics testing equipment, and the transistors still work properly, I might toss a few on Ebay. I imagine they're very hard to come by for people who need replacements on vintage sound equipment. It looks like I have about 100 of those across all the Hammond boards I got.