*riii* Cans, glass jars, paper packets, cardboard boxes and plastic bottles began to emerge from a split in the bottom of a shopping bag in what seemed like slow motion. An ear-shattering jumble of sounds followed as the groceries met the bitumen carpark.
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*muh-blu-blup, muh-blup-blup, muh-blup-blup, muh-blup-blup, muh-blup-blup*
The contents of Alec Guiness's glass bottles, vials and beakers bubbled merrily away, making the now famous sound.
While we're all trying to be green and reduce landfill, what would happen if we tried too hard? The Man In The White Suit is a wonderful example of just this. From an engineering perspective, I find it just as frustrating. If for no other reason, I will never be a designer while we disagree over functionality versus consumer appeal.
It was threatened at one stage in Australia that the sale of HDPE shopping bags would be completely outlawed. The ACCC managed to get all major retailers to be "responsible" though, and do two things. Firstly, "plastic" bags are still available at point of sale at a cost of $0.10 a piece. "Green bags" cost roughly $1.25, but are designed to be used again and again. Contrary to what the name suggests, many are no longer green in colour, but rather may be even Louis Vitton patterned. These bags are made of polypropylene mesh cloth, still plastic, just like the polyethylene ones.
Dimensions seem to be inconsistent between stores let alone countries, but construction seems fairly universal, so this should apply regardless of where you picked yours up. Aussie bags are constructed of nine individual pieces and fourteen separate seams. The two handles are each two strips an inch wide, placed back to back then sewn on with a a seam around their edge. The handles run from the point where the base and side wall meet, up the height of the bag, an arbitrary distance that is at least as long as the spacing between the points where the handle joins the top of the bag, to the top of the opposite side of the same panel, and finally back down to the bottom again.
A fairly flimsy sheet of polypropylene is usually placed in the base of the bag for rigidity. This also redistributes the weight of the contents to directly on the horizontal run of the side seams. Remember that while the cloth of the bag is fibrous, it is not woven per se. An outer strengthener covers the join of the centre section (end-base-end) and sides on the outside. The use of this strengthener does not directly exclude the ability of the handles to continue under the bag from one side to the other.
Green bags can sustain holding roughly 20kg, enough for 6x 3L bottles of milk, theoretically enough anyway. That's over the physical volumetric capacity of the bag. Extending the handles across the underside of the bag however, should bump this up to 30kg. My climbing carabiners can hold 200kg, making my 57kg of body mass seem easy meat. Just as the load on those carabiners reaches nearly 130kg when I'm abseiling, the load on every part of those shopping bags goes up when the bag is lifted or you swing your arms as you walk. Swing a bottle containing liquid, and as the contents sloshes around inside, the stress on the bag goes up even more. The safe maximum weight capacity of a green bag is closer to 12kg, or 4x 3L bottles of milk. If you think about using these bags every week/fortnight for your family grocery shopping, having to distribute the items between bags such that milk and flour don't end up together nor meat and washing powder, keeping the weight down comes at a compromise to how many bags you then have to carry.
Carry? Don't you load the bags into the trolley to get them out to your car? No, for the simple reason that the size and shape of shopping trolleys was ignored when these bags were designed. A shopping trolley fits two layers of 1x landscape + 2x portrait bags. Due to the taper of shopping trolleys required for them to be able to stack, only one green bag fits at the front, and sideways. The size of the average green bag isn't optimised for fitting groceries in it either, I checked on that in case that had taken precedence in design considerations. Breakfast cereal boxes are either too wide to get in the bag or too narrow to get anything down beside, and no size of can seems to fit neatly.
So, for being something that we are supposed to use regularly as a complete replacement for an existing and functional product, what was going through the minds of the creators of this new way to save the planet? Something similar to what the girl was thinking who designed the recycled plastic bus stop shelters we have that drip water on you when it rains I guess.