OddThinking

Wow. I think the table is an interesting start, but way too simple to find the reason. Among factors that should be included are:

Weight of packaging vs. shipping cost (glass is much heavier than plastic for example)

How easy the packaging material is to recycle (glass and paper easier than plastic, AFAIK)

How much consumers expect certain things in certain packaging. Some brands only use different packaging to differentiate from others.

In South Africa, I have not seen any fruit juices offered in glass bottles for a very long time now.

This post really fits in with the name of the blog, I have to say.

Correction – flavoured milk is available in plastic bottles, infact it’s the size-de-jure for >350ml.

Mr Rohan,

Corrected, thank you. I realise the reason I missed it was I tried to imagine ever seing flavoured milk in a transparent plastic bottle, like plain milk. I couldn’t visualise it.

But of course, it is available in opaque bottles, that might give us a clue.

I agree with Bork that there are many factors that affect the choice of column – packaging costs, recycleability, weight.

However, that doesn’t explain why we don’t see the same column choices for every row.

What are the differences between the rows – the different fluids – that requires differences in presentation? I didn’t mention that fizzy drinks are never presented in cardboard containers, because there is an obvious need to store them in rigid containers to prevent them going flat. The specific needs for the other drinks seem less obvious.

Let me throw out some conjectures, that may go some way toward the answer.

• Suppose glass is (now) more expensive to create+ship than plastic or paper. That would be a manufacturing pressure away from glass. However, if consumers felt preferred glass (maybe it was seen as more classy), that would be a pressure towards it. Glass might only become worthwhile for the more expensive drinks. Hence, only branded high-end water and juice might appear in glass bottles, where the price-difference would be acceptable.
• Is there a preference when it comes to water to be able to see that it is clear before drinking it? That would explain no cardboard containers.
• Many people like to carry water and sip it slowly – more so than other drinks? A re-sealable cap is necessary.
• Does the flavouring of flavoured milk settle to the bottom? Does that make it appear unappealing on the shelf, and hence the need for opaque containers.
• I have heard of sunlight being used to treat water in plastic bottles in developing countries. Is there some effect there that encourages transparent bottles to increase shelf-life? Does light affect the taste of milk?
• Milk has a shorter shelf-life than juice and water. There is likely to be more expired milk containers thrown out by retailers and distributors, unpurchased. Does that further drive the need for cheaper containers?
• Most containers have a pocket of air, except the bricks. Does that affect shelf-life, especially for long-life milk?

I emphasize: all this is just conjecture.

I heard some economics or business professor on NPR (public radio in the U.S.) talking about how economics drives everything, and he said that the reason for square cartons for milk was due to the high cost of refrigeration, thus the desire to pack more milk into the same storage space.

It’s certainly not a bad reason, but he didn’t explain why we don’t then use square containers for every refrigerated drink.

As for flavored milk containers, it seems there is quite a variety, including some translucent and even transparent ones. (I will not argue the prevalence of such containers, but they exist, or existed in the reasonably recent past.)

Updated with local observations of John and Bork.

For Australian milk, we have gone from round glass bottles, to square (gable-top) cardboard, and now we are seeing more round plastic bottles. I wonder if (cheap) square plastic bottles are feasible. Does the price differential between plastic-coated cardboard and plastic outweigh the extra refrigeration required?

Re: Flavoured milk containers: Given a big enough marketplace, I guess we will eventually see every combination. If this was a serious topic of research, I would tag the cells by market-share. Glass bottles of water and flavoured milk exist, it seems, but I would think have less than a 1% market-share where they compete against plastic bottles. Juice may be the same.

p.s. John, your nice example of Julian links was noted!

1. Just the other day, at the small NSW country town of Bulahdelah I bought a glass bottle of Coke Zero that had a non-twistable metal bottle cap, ie: it required a bottle-opener to open it – which struck me as quirky & archaic (especially as Coke Zero is a relatively new product). I thought maybe it was special packaging for the tourist trade in quaint country towns (the stereotypically friendly & hospitable store owner thoughtfully handed me the bottle opener with my change). So I was thinking about drink packaging most of the rest of the way back to Sydney. Then I saw this blog post & realised that Julian really HAS been stealing my thoughts, just like the pixies warned me!

2. I did some truck driving for a milk distributor a while back & was intrigued to see how much of the infrastructure was based on the design of the plastic milk crates. Factory conveyor lines, forklift trucks, loading ramps, all were designed to be compatible with moving rows of milk crates so they could be stacked efficiently into the trucks & warehouses without further packaging. I assumed that the size & shape of the milk cartons was also made to fit these crates.

3. I note Julian’s noting John’s use of Julian links. The quest is off to a good start! Julian links rule!!

Not really an answer, but I believe John was listening to Robert H. Frank the author of “The Economic Rationalist”

This book has a section that notes that beverages that are typically consumed directly from their containers tend to be in containers that are round. His rationale for square-ness for milk and roundness for soft drinks is as John describes: that soft drinks tend to be stored in cheap, open shelves, and milk tends to be stored in expensive refrigeration where they need to pack densely.

The section immediately after this ponders why aluminium cans are constructed inefficiently. Shorter, wider cans would use less raw material and presumably be cheaper to manufacture. The answer offered is that people perceive taller containers to be more voluminous.

But I digress…

Chris,

Not that I know anything about these sort of things, but I would have expected the tightly-packed array of milk cartons to be counter to efficient refrigeration. I seem to remember reading that it is relatively inefficient to pack your freezer to occupy every cubic centimetre; maximal cooling efficiency is afforded by some air around the items to be cooled. (And I guess convection would be the source of air movement in this case).

However, just thinking about it some more now, the average supermarket refrigerator probably doesn’t rely on air movement for heat transfer. They seem to chill the milk cartons from below, and this would also justify packing the milk as tightly as possible.

This explains the difference in shape between cans and cartons: as a cause or effect of the different refrigeration techniques employed. In my experience cans are stored in more familiar, enclosed, refrigerators. These probably rely on air circulation to cool effectively.

What do you reckon? Sound plausible?

Maybe it makes sense to have air-gaps to quickly chill some warm milk, but I would have expected that, once your milk is at the desired temperature (e.g. in a crate leaving the factory or in the fridge of a supermarket) tightly packing it is the best way to maintain the temperature.

I am trying to remember enough of my physics to defend this position, but I am having trouble doing so.

There was a straight dope column regarding this a while back. The upshot is that sparsely packed fridges cool down more quickly, but that tightly packed fridges are more overall efficient. The reason was because of the convection when you opened a fridge.

http://www.straightdope.com/columns/060616.html

It seems unlikely that the shapes of milk containers is designed to force sparseness.

-D

Milk has it’s proteins destroyed by UV light from fluorescent lighting.

Cardboard milk cartons stop UV light from reaching the milk. I assume the same is true of the plastic containers and have a vague recollection of their being something added to plastic milk containers to stop UV light.

Water is immune to UV light.

Cardboard cartons are most likely rectangular because it’s much easier to produce from a flat piece of cardboard on an assembly line.

Obviously if there is a juice that is adversely affected by UV light it will be in a plastic or cardboard carton/Tetra Pak container.

Anything else has to do with marketing, costs and how the product is going to be used by the customer.

Michael O’Ryan is right about the problems of UV and milk. Presumably the opaque and translucent containers try to address that problem.

That makes me wonder about the examples of transparent plastic containers for plain milk. Do they have UV-blocking properties, even while they are transparent? I wonder how I could test that or find it out.

Seth Godin discusses water bottle packaging weights with some info about filling techniques.

Mike Pope discusses the history of innovation in milk container design.

Thanks to Julian for helping me with homework!