What is a "Sintered" planchet?

ms70

Never heard of it before.

eBay Link

xbob

From my understanding, it's a planchet that during the washing process goes in a bath previously used for copper. So copper somehow adheres to the planchet and gives it a different coloring. I thought they were supposed to be copper colored but it seems some are also near black.

I know other members probably have a better explanation or at least confirm or correct mine.

I had a thread about this the other day - maybe my dime is Sintered afterall?? link - dimes

indianabyron

Here is what a sintered coin is all about and how it happens. A blank or planchet which stuck in the annealing drum and was partially or completely coated with sintered coin dust. The heat is not great enough to melt the powder. but it is great enough to produce a sintering action which will put a hard powder coating of significant thicjness on the stuck planchet. The sintered coating is strong enough to withstand the stress of the upsetting mill and will usally stay attached to the planchet through further processing. the principal cause is worn equipment which allows the blank or planchet to stick or jam in the crevices in the annealing drum.



There you go

Byron

BAJJERFAN

A sintered planchet is one that has been heated to a high temperature but not high enough to melt the metal.

MajorDuty

I like Sponge Bob's explanation.

ms70

Thank you everyone for your responses. The learning process never stops in this hobby!

KurtHorn

<< <i>Thank you everyone for your responses. The learning process never stops in this hobby! >>



Especially when you get three completely different explanations... I wonder if HomerunHall or someone else from PCGS could explain what really causes this...

errormaven

People apply the terms "copper wash" and "sintered plating" to such copper-colored coins, under the assumption that:

a. the coin picked up a coating of copper from a rinse bath saturated with copper ions, or

b. picked up a coating of copper from an annealing drum filled with copper dust.

Both theories are speculative and have not been corroborated experimentally.

Neither of the theories explain why:

1. Colors vary between bright copper, brown, black, and red, even on the same coin.

2. Many nickels with a heavy coating of copper are significantly UNDERWEIGHT.

3. Where the copper comes from after 1982, when obvious sources of copper ions are lacking. Copper-plated zinc planchets are neither washed nor annealed. They lack tumbling marks.

4. Composite copper-and-nickel layers flake off.

5. Nickel colored areas sometimes flake off.

6. The underlying metal is sometimes brown or black.

7. The nickel-colored areas sometimes split to reveal underlying copper.

8. Coverage is often so patchy.

The theory I favor -- admittedly speculative -- is that in the rinse bath, copper ions are preferentially liberated from Cu-Ni and clad coins, and then re-deposited on new batches of coins when the solution becomes saturated.

However, this theory does not provide an answer for many of the anomalies listed above.

You should regard any explanation for how a mint error is caused with a great deal of skepticism. There are many myths and unsupported statements of fact floating around out there.

cladking

There is a lot going on at the mint and the many different types of coins, errors, finishes etc are
proof of it. There may well be a few different ways that these are produced even at any given
time.

Errormaven's explanation is a good one and the others can't be ruled out.

errormaven

Cladking may be right that we're dealing with more than one phenomenon.

Mint discoloration extends beyond the classic copper, brown, red, and black of "copper wash" and "sintered plating errors" to include coins that appear green, green-gold, yellow-gold, purple, orange, pewter, and slate gray. A fair percentage of these show an unexplained streakiness.

Nobody knows the cause of this rainbow of colors or the streaks. Heck, nobody really understands copper wash and sintered plating. But the extraordinary variation in color suggests more than one process is involved.

WWW

Here's an odd looking example (which I was told was a copper wash) that I found a while back:

BAJJERFAN

I have one of those I picked from a Philly mint roll. Looks blue black in color like it was impact plated with graphite.

downhome

WWW thats some great coin photography......

MrSpud

I think this coin pictured below is a sintered planchet. It belongs to MrsSpuds Uncle Jerry. I'll get to hear what NGC thinks it is because Uncle Jerry took it over to NGC (he lives about 1/2 hour away from them) and asked them if they thought it was worth slabbing as an error. They told him yes. He is expecting it back from them any day now.

clackamas

Dang I have found numerous examples of these. I just toss them back.

errormaven

The 1994 quarter looks more like toning that occurred after the strike. The pinhole gaps are not typical of any form of mint discoloration I am familiar with.

The peace nickel does look like a case of "sintered plating". The presence of both copper/red and black areas is a familiar pattern. The sharp boundary between red and black areas would indicate the presence of thin plating (red area) that possibly flaked off before the strike, exposing an underlying black surface.

I've seen many similar nickels, including the recent bison design. So whatever is causing these "sintered plating" and "copper wash" errors has been going on continuously since at least the late 1950's

indianabyron

Copperwash and sintering are 2 different thing. One is a chemical wash caused by the disolved copper adhearing to the planchet(copperwash) Sintering is caused by the small bits of nickle and copper or other metal that are rubbed knicked or otherwise removed from the planchets or the drum they spin in, it sticks to the planchet and then is annealed to soften the planchet before striking. The annealing step bakes the sintering on.

As you can read or see they are both totally different thing, and are in no way even close to being the same thing.

All the sintering ive seen has been black or brown in color. The copper is well its copper colored. Sintering dosent just happen to coins it can happen to any metal that has been exposed to dust that has coated it, then is heated to anneal it. Copperwashing is a chemical process and sintering is a physical process if that makes any sence.


Byron

errormaven

I am familiar with the theory behind both "copper wash" and "sintered plating" errors. I realize they are entirely different theoretical processes. Yet, I find identical-looking errors being slabbed as one or the other, indiscriminately.

The two errors form an unbroken continuum, which makes me suspect that one or the other theory (or both) are deeply flawed when it comes to explaining oddly-colored and/or strangley-plated clad and Cu-Ni coins.

Try not to believe everything you read when it comes to error coin theorizing. Folks at the Mint and error coin "experts" often make educated guesses, which, with time, take on the appearance of fact.

Any theory must be congruent with the physical evidence. As I laid out in my first post, the physical evidence is not fully congruent with either theory. We're all missing something.

cladking

<< <i>

Any theory must be congruent with the physical evidence. As I laid out in my first post, the physical evidence is not fully congruent with either theory. We're all missing something. >>



Speaking of which; have you ever seen clads that were sintered or affected on
only one side? I'm wondering if possibly some of these might come in on the strip.

errormaven

<< <i>Speaking of which; have you ever seen clads that were sintered or affected on
only one side? I'm wondering if possibly some of these might come in on the strip. >>



Quite a few. Coverage can be one-sided, can cover one entire face and part of the other face, or it can be decidedly patchy.

I don't think the errors can be traced back to problems with the strip. The edge of these coins is often as fully discolored or as thickly plated as the rest of the coin. The blanking die should leave a partly or completely fresh surface on the coin's edge.