Surprise! If you are a regular reader of Cockeyed.com, you know that I've been completely obsessed with the Eyeclops bionic eye camera toy, and that I've pretty much taken a close look at everything I can get my hands on. So, alphabetically, following Velcro and Yarn I now present a very close look at Ziplock plastic bag closures. Unfortunately, I didn't actually have any Ziploc brand bags on hand, so I used a generic version from Target and a GLAD version, with the catchy "GLAD food storage bags" name. I'm also a fan of the crazy-sized Uline plastic bags. As you may know, Ziploc bags can have either a single zipper, or a double-zipper.

Here is a view of the cross section of a single zipper closure.

With the Eyeclops, we get a closeup of the cross section. This could be called the female side of the closure.

Ka-bam! LOCKED! With a well-aimed snap, the other half pushes in and is caught by the meat hooks on the other side. Now, the two halves are locked together strongly. Only a strong pull, (such as jealousy or drug addiction) can pull them apart when they are locked together like this.

Here is a slightly different angle, to remind you that this connection happens along a long C-shaped channel which is (somehow) fused to the plastic bag.

Same view, connected with the opposite channel.

Here is a look at a cross-section of the "double zipper seal" which is used in most larger food storage bags. Open.

And sealed.

The "double" seal is more robust, but it doesn't actually have more connection hooks. The "male" side of the single zipper seal is split, creating two independent hooks from one mushroom-cap shaft.

This connection is a little bit too large for the extreme magnification of the eyeclops. I couldn't fit the whole thing onto my screen at once. Here is a photo of half of the connection.

Under the high-powered magnification of the Eyeclops, I started to notice some new features of these re-sealable bags. These features are visible to the naked eye, I just hadn't noticed them before. At the top of the bags are two long ridges, which I call the "edge grip". This ridge helps fat fingers find and grip the edges of the plastic bag. The "edge grip" is very important. It is fused to (or extruded with) the plastic film of the bag in the same way as the ziplock mechanism, and it is almost as important as the seal itself. This probably sounds crazy. You should decide for yourself. Buy some lunch meat or cheese in a re-sealable bag. These "cut-once, re-seal many" bags usually leave out the edge grip strips, creating a bag mouth which is much more difficult to re-open than regular ziplock bags. In fact, I'll bet that the invention of the Ziplock bag closure was a side-innovation, discovered while figuring out another problem: How to make the mouths of plastic bags easier to open. I also noticed a textured area surrounding the seals, making the plastic easier to grip.

The GLAD Brand food bags use two colors for the different sides of their seal, creating a miniature Men's Wearhouse logo. They introduced their bags years ago with a "yellow and blue makes green, its sealed!" marketing campaign.

Up close, with the view of the Eyeclops, the tiny hooks and peaks are a little ragged. This might have happened when I cut across the seal with scissors to see the cross section. Is this seal watertight? Mostly. In this view, water would have to try to flow from left to right, past two hook lock channels.

Here is a view of one of the edge grips. Man, those tiny things do a big job. I literally can not think of a smaller handle which is used by human hands. The clear film for these bags is 1.6 mils thick, which you can see here on edge.

Finally, the sliding zip lock zipper bag. When I first noticed this type of ziplock bag, I figured it was for people with poor dexterity, like Yeti and half-orcs. They are definitely the most expensive, sold in boxes of just 15.

Here is a cross-section view of the seal. At this level of magnification, it looks like a solid connection.

The connecion is made by dragging this red zipper across the bag opening. Here is an inside view. It is a lot like a regular zipper, complete with alignment guides.

This is the view of the bag seal magnified by 200 times. The connection is an incredibly tight handshake between the two channels. This looks like a waterproof seal!