Mylar Storage Bags

I've been experimenting for a while now with using heavy duty Mylar bags for the storage of bulk blends. The ones I'm using are 5 mil. metalized ziplock bags and from what I can tell the vapor transport through the material is as close to zero as as makes no difference. I use an impulse sealer on the top flap of the bags but a hot iron could be used as well. I currently have about fifteen pounds of 12 different blends sitting in a Rubbermaid tub and there is absolutely no smell of tobacco in the bin, at all. Not even well sealed tins can manage that feat.
The bags could deteriorate over time but as they are not being exposed to light or varying temps I expect them to stay sealed for a good long time, several years at a minimum, and possibly quite a lot longer. I'd say the minimum spec for a bag in this application would be a 5 mil thickness fully metalized Mylar product.
I decided to give the bags a shot because I haven't had the best of luck with Mason jars, breakage plus the occasional poor seal, and I think this is going to be a viable alternative to jars. It's certainly a lightproof and less breakable alternative. It might even turn out to be an improvement.

Here's where I got mine;
Mylar Pro
They come with oxygen absorbers for the prepper crowd but I have no need for 'em so I just pitch 'em.
Buzkirk they are cheaper than jars but that's not the reason I switched to them.

All of the information I've been able to find on Mylar bags is from prepper sites and concerns food storage. There is general agreement that the limiting factor is the type of food itself rather than the bag. Bags kept in a benign environment are good for far longer, some say up to 25 years, than what is kept in them. In the case of tobacco we know that certain types of blends keep just fine, and in many cases improve significantly, for multi-decadal periods so their storage limitations substantially exceed that of conventional foodstuffs.
In my case the bags will be kept in an air-conditioned environment in an opaque Rubbermaid bin so I'm fairly confident that the bag material will not deteriorate significantly for at least ten years which is more than sufficient for my needs. I am using an impulse style sealer which makes a uniform 2.5mm seal which appears invulnerable to all but gross abuse. The sides and bottom of the Mylar Pro brand bags have an approximately 1/4" heavy duty seal which seems very robust indeed and highly unlikely to fail. The bag flap above the ziplock seal is about an inch and a half wide and could, if desired, be hot ironed into a one inch seal that would rival the best tin or canning jar seal. If one were so inclined an impulse sealer could be used to make a double or triple seal that would be proof against anything except a concerted attack with sharp objects.
I think these bags are going to meet the case very nicely.

All of the pouches I've come across are made of much thinner material than the bags I'm using plus they do not have the vacuum applied aluminum coating that makes them opaque and increases the strength of the vapor barrier. I have inserted the bags the bulk blends came in into the metalized Mylar bags so it's conceivable that some plastic taste could eventually be transferred to the tobacco but I consider it unlikely to be much of a problem. Actually putting the tobacco alone into the Mylar bag might be slightly preferable since it would be bearing on the metalized surface instead of the plastic itself. I really couldn't say whether or not the plastic used in the bags I have is of a higher quality than that used in tobacco pouches but I am sure that the metalized surface makes a big difference in the performance we seek for our peculiar needs.
Frequent handling and resealing of these bags is probably not going to do their structural integrity any good but then frequent handling of any storage system is going to make how well it seals pretty much beside the point. Currently I have a pouch of Condor in a Mylar bag that is only ziplocked. The pouch itself reeks of that good ol' Lakeland essence but the smell is undetectable when inside the Mylar and that's without it being heat-sealed.

Strictly speaking an impulse sealer is not needed but I like using one because it makes a nice uniform straight seal. Also if you put the seal near the top of the bag flap then when you cut it off to pull tobacco out you can make another seal no sweat. Might be able to do three iterations that way. The ziplock closures on these bags are very robust so they are going to be a big improvement over opened tins even if not heat sealed. If they made a bag with the same zip seal but doubled or tripled then heat sealing might be entirely superfluous.

You do want to have oxygen in the bag so squishing it gently, pressing the zip seal and then heat-sealing should be ideal for the aging process, no vaccum needed. Also you would, for the obvious reason, not use oxygen absorbers in the bag. Also I've read that Foodsavers don't get hot enough for a really good seal on thick Mylar.