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Cold Sea

Proof-like coins

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Cold Sea

Prooflike grading was discussed recently, and this made me wonder about the actual minting process.


I found the following which applied to the Canadian mint between 1948 and 1968:


When striking proof-like coins the mint used regular dies, often ones used previously. The dies were cleaned and sometimes pickled in a bath of dilute nitric acid. The acid bath left a fragile 'bloom' that could easily be scraped off. The dies were then polished. This polishing removed the bloom from the fields but not from the devices. When the coins were struck the bloom produced cameo-like devices on polished fields. The pressure of striking quickly caused the bloom to wear off and the cameo effect to fade. The first coins to be struck (maybe only the first 3 to 5) developed what we now call an ultra-heavy cameo appearance. With the pressure and friction of striking each successive coin had somewhat less contrast. Later coins were heavy cameo and this rapidly wore to a cameo effect. Even this wore quickly and the vast majority of proof-like coins do not exhibit any contrast between the devices and the fields, even for exceptional high grade pieces.


Geejay mentioned in a “scarce coin watch” posting about the 1947 5 shilling PL, that these were minted using proof dies that were scrubbed (I am not sure what is meant by scrubbed. Maybe Geejay can elaborate on this).


I wonder if I can assume then that a prooflike coin was single struck using polished, proof or regular, dies on a regular planchet (proof coins would use a polished planchet).


Understanding the minting process might make it easier identifying this type of coin. The grading side of things I will stay out of.

Edited by Cold Sea

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Not sure how they were manufactured (struck) but it is interesting to note that the Crowns (5/-) pieces were the only Union coin struck in this "proof-like" condition (also called SS = specially selected)


They were struck on the same two presses that struck the ZAR Single Shaft 1892 5/- pieces.


They were probably struck for collectors who did not want (or could afford) the proof sets and only wanted the 5/- pieces for their collections?


The first year (1947) had no proof-like 5/- pieces struck and interestingly enough, the dates 1948, 1951, 1952 and 1955 had LESS SS proof-like crowns struck than actual proofs.








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