When I started purchasing and organizig the four separate bug-out-bags for my children and their families, I started by categorizing the materials and grouping them in heavy 4 and 6 mil plastic zip loc bags (www.royalbag.com) . The categories were divided per use e.g., fire starting, cooking, sleeping, navigation and signaling etc., and the white panel on each bag allowed me to list the items within.
I showed the kits to a very savvy friend and he asked if I was going to vacuum seal these bags to eliminate the air space within the bag. I had thought of this previously but am unsure of the advantages. The MRE's are already sealed as are the SOS high caloric bars. If one were to have to cross a river or find themselves in the drink with one of these bags (probably 30 pounds within a Maxpedition pack) the airspace within the ziplocs would keep the bag afloat. Yet these are long term packs and, with the exception of those items that need rotation (Batteries, MRE') I want the materials in them to last a lifetime.
Let me hear your input on vacuum packaging, buoyancy, longevity and other factors related to vacuum packaging. Thank you.

I have a small Tilia "Foodsaver" vacuum sealer that they used to have at Wally World for about $35. I believe it's called the "Mini". Might be too small for what you're looking to seal, but they also make bigger ones.

It sounds like this is a kit you will keep sealed up and don't want the contents pilfered. Vacuum sealing is a great idea for that.

My day to day stuff in my BoB I just keep in the handy ol' Ziploc baggies, in case I need access. The trunk kit has most items vacuum sealed.

Plus, it's fun to seal stuff up! <img src="/images/graemlins/cool.gif" alt="" />

You mentioned that you are using 4 and 6 mil zip top bags. Do you know how thick the regular zip top bags are that you can get in the grocery store?

I believe most store bought Zip Locs are less than two mil. If I were to encapsulate these kits ( I too have avacuum sealer) I'd include the heavy zip locks within the vacuum bag. Not only can these heavy bags be used tor other purposes but once the vacuum seal bag is broken open (in the field) it no longer can be closed. The 4 and 6 mil bags are typical in weight to what the military uses.

I like the idea of vacuum sealing the existing zip lock bags. Good protection for very little weight and space. If you have extra room, and want to add buoyancy, you could add the filled air packing material that seems to come with every Internet order these days. It is just a sealed bag of air, so no weight. If you need an additional plastic bag, open it and use it. If you need to add stuff later, discard it.

I also use the foodsaver, and have many of my PSK, BOB, and FAK components vac packed. You can cut the bags up and make them very small. For instance, my medications, my fire kit (PJ/cotton balls), and other items that could benefit from being tightly packed and waterproof. I have a very small pocket fak (minor cuts/scrapes, really) no bigger than a credit card (well, about 3/8"thick)which is also so packed.
In my BOB and larger kits, I vac pack clothing, also. You'd be amazed how much you can squeeze down a watch cap, gloves, socks, etc. The advantages over zip lock are that the bags are much sturdier, you can boil food in them, and the foodsaver draws them up much tighter than you can do sitting on a zip lock bag.

I see the primary disadvantage as lack or resealability, and that you have to cut them open (unless you have scary-sharp teeth you're willing to risk). I make mine a good deal longer at the "neck" than necessary. Once shrunk and sealed, I just roll the excess around the bag. That way I have enough material to roll up as a temporary closure once opened.

I find that a combination of vacuum sealing individual use compartments (such as would hold one tinder quick, or two or three matches, or one piece of candy), the repackaging in ziplocs is the best approach. The indidual use items are well protected, yet can be had without compromising the entire supply, while the ziplocs keep it all together. Ziplocs are easy to suck down ( I usually suck all the air out at the corner of the opening, creating a small aperture at the end that is pretty easy to control). It is not a vacuum seal, in that I can't quite draw that hard, but it is well compressed, repeatable, and doesn't tend to leak.

Freezer ziplocs are a lot thicker and sturdier than regular ziplocs. I like using the freezer bags.

So are folks using the special rolls of plastic that are sold alongside the vacuum sealers in the store?

Here's an example of the Foodsaver bags in various sizes and the rolls for making your own custom sizes:

http://foodsaver.jardendirect.com/products.ad2?catalogID=1002

I have some of the quart and pint bags, and a custom roll or two. The pint bags work really well for the smaller items.