I'm 100 percent sure I am not. Plastic is not air tight, basically nothing on earth is and the things that are belong to things like NASA not plastic bags that cost a few cents
Mylar? Meow bought some bags for comic books a long time ago. They where supposed to be the best thing to store them in back then.
There are plenty of documents that give "which" and "reasons" , if you want data , there is plenty on the internet. Polyethylene terephthalate, commonly known as mylar is the best for this as it is very transparent and low transmission. There are better to store metal from gases, but they generally are semimetallic and low transparency. here is a chart with gas and water vapor permeabilities. http://www.alphap.com/bottle-basics/plastics-comparison-chart.php
Now there is a post, and a poster who knows what they are talking about; And can back it up. Thanks for the info.
I like to look at my coins I store them in categorized airtight/watertight containers such as, say Tupperware containers. In the containers I also put a rechargeable silica dehumidity pack and an anti-tarnish strip. This allows me to pull them out (and recharge the packet) look at the coins, etc. So whether you store it in a gun safe with other things in there or not, they should be well protected. Just don't store them anyplace that has direct sunlight, in space or anything out of the ordinary.
I used to use these all the time in the old days with jewelry stuff. silver beads, etc etc. I throw them in each container that I have for anything silver. Even my musical instruments that have silver plating. https://www.amazon.com/3M-Anti-Tarnish-Silver-Protector-Strips/dp/B004PWMQNI basically when you put your stuff in a sealed container you are also locking in the air environment you are in. Thus the dehumidifier packets and anti-tarnish strips to help "sterlize" the air from pollutants/humidity creating a more controlled environment on the cheap.
Currently no. Although Meow has been thinking about it for awhile. There was a Proof Canada quarter Meow contemplated buying with a feline on it, but Meow decided at least for now; That this Cat will collect only US Mint issues. Are there any US Mint coins with Cats on them? If so, Meow would want that for sure. If you have a favorite coin depicting a Feline, please share an image with us.
The Isle of Man has a series of cat coins. https://colnect.com/en/coins/list/country/1871-Isle_of_Man/series/63580-I77_-_One_Crown_Cats_Silver The closest that I can think of on US coins are the 1927 Vermont Commem Half and the 2017 Lions Club Dollar: https://www.ngccoin.com/coin-explor...ves-pscid-71/1927-vermont-50c-ms-coinid-19401 https://catalog.usmint.gov/lions-clubs-international-2017-centennial-proof-silver-dollar-17CH.html
Manx Cats! Meow's tailless brethren! Meow has seen those, and at one time considered buying some. Especially since Meow absolutely loved the movie "Mindhorn". The Vermont looks like it would be a little too pricey for Meow, but Meow did buy a Lions Club silver Dollars in both finishes.
My favorite cat coins: Hungary 100 (copper-nickel) and 200 (silver) Forint 1985. Neither are expensive issues.
OK now, that is something Meow would want! Inexpensive you say? Meow has an errand to run soon, but will look further into later.
Even if the seal on the bags maintains its integrity, the plastic itself is air permeable. That means the air goes right through the face of the plastic itself. Bottom line, no plastic bag of any kind is airtight. If you don't want to believe that, try this. Take one of your vacuum bags and fill it Oreo cookies. Suck all the air out. Then put the bag of cookies on the counter, in a cabinet, top of the fridge - wherever you'd normally keep them. Next morning, go pick that bag of cookies up, do not open it, and put it up to your nose - take a smell. You will smell the Oreo cookies. The fact that you can smell them proves the plastic itself is air permeable - that air goes right through the plastic itself.