Reply to a Recent Posting: "Roosevelt Dime folder viewable from both sides"?

This was my reply to a recent posting by @masterswimmer posing the question: "Roosevelt dime folder viewable from both sides". My response was late in the evening so it didn't get much, if any observation; I thought it might be of a general interest so I am re-posting it here with some minor changes:

Anyone else interested in the Meghrig Coin Boards, and how they contribute to toning, here is my eBay Listing from 2016 with background info and images of one of the coins that were contained in the Boards:

"Listing Title:

Vintage MEGHRIG COIN BOARD SET for Roosevelt Dimes 1946 & Up ~ holds 72 Coins

Vintage MEGHRIG COIN BOARD SET (COINS NOT INCLUDED) of 4 Boards with Acetate Slides, holds 72 total Roosevelt Dimes (No. 1374RD-1 1946-1951-S; No. 1374RD-2 1952-1958-D; No. 1374RD-3 1959-UP; No. 1456 PLAIN, No Factory Printing). The Boards are in GOOD USED Condition with minimal wear, and the Slides are clean and free of excessive scratch lines; the No. 1374RD-3 and No. 1456 have hand-written date/mint mark/type information for coins that were issued after the manufacturing date of 1961.

The Meghrig Boards NO. 1374RD-1 thru 1374RD-3, and No. 1456 ( approximate size 7-7/8”L x 5-7/8”W x 1/8”T) are part of the American Album Series (these Boards were intended to be mounted in an Album similar to a 3-Ring Binder) and were the successor to the Waite-Raymond Albums. The Meghrig products were produced by M. Meghrig and Sons from the early 1950’s to 1965, when production ceased—which makes them a Collector’s Item in themselves! These Boards are truly great for protecting and displaying your coins (both sides are visible); they feature Clear Acetate Slides that protect the coin from contact with objects (e.g. dirty greasy fingers) and also act as a retainer to prevent the coin from falling out. In actual practice, the thickness of the Board and the precision Cutout tend to keep the coin from moving too much once it is inserted and centered in the opening. The inadvertent—but much appreciated (by some) side effect of the acetate Slide—is to provide a nearly sealed chamber for the sulfur compounds inherent in the construction of the Board to outgas over time and yield the colorful toning that you see in the photos of the Coins that were originally housed in these Boards."

NOTE: once I sold the Boards I deleted the photos of them, but I still have my photos of the original coins as they were mounted in the Board, with the Acetate slide removed for the purpose of photographing the coin(s). Here is a photo one of the coins, the key 1949-S, that is representative the kind of toning that these coins picked up:



The amount of toning and the resultant color palate of coins in the enclosed environment of the Board is dependent on several factors: (1) length of time that the coin was in the Board; (2) condition of the coin's surface (i.e. preparation of blanks, granularity of struck surface; foreign material on the surface from the minting operation, and bagging and handling operations); (3) remaining sulfur compounds in the Board Layers that can still outgas as time goes on.