You Can Thank The Metric System For The Milk Bag

They look like plastic pillows or squishy rectangular balloons. Lined up in grocery store refrigerator rows, they can sometimes seem like a sci-fi space product to tourists (or even to Canadians from more westerly provinces).

But to many folks in Ontario, Quebec and the Maritimes, the squishy white sacs are a symbol of comfort and nostalgia. After all, many of us grew up cutting out a little plastic triangle in the upper corner of the milk bag and pouring from it into our cereal bowls each morning.

Mostly sold in four-litre quantities, we may call it “a bag of milk,” but technically it is really three smaller, clear bags of milk tucked into a larger coloured bag, fastened shut with the plastic tag that also closes bags of sandwich bread.

While the milk bag has become more popular over the last 50 or so years, even at an international level, bags of milk have the strongest Canadian history in Ontario. That is where about 75 to 80 per cent of all dairy milk sold comes in a plastic bag format. Roughly half of Canadian dairy milk drinkers purchase theirs in the floppy bag form today.

A 1997 report from the Environment and Plastics Industry Council found that the sale of plastic milk bags made up more than 83 per cent of the Canadian market and cut solid waste generated by the industry by 20 per cent.

But where did the idea of the milk bag come from? What sets it apart from its glass-jug or cardboard container peers even to this day?

And why did it start – then stop – taking over the world?

Milk bags have been a regular part of breakfast rituals in Ontario, Quebec and the Maritimes for the last 50 years. Photo credit: Annie Spratt.



A simple history

From the dawn of residential refrigeration, milk men delivered glass jugs of fresh milk to Canadian homes. This was a regular and commonplace occurrence in the first half of the 20th century.

As well, lighter plastic jugs started to emerge on the scene around 1915 but only got quite popular around the 60s. That was when plastic milk jugs were invented specifically to extend milk’s shelf life.

Around that time, in 1967 to 1968, American chemical company DuPont took plastic milk containers to the next level. The company introduced its polyethylene milk bag, then partnered with Guaranteed Pure Milk Co. to test the product out in Montreal and Vancouver markets.

Manufacturers found plastic more convenient due to its lower weight in comparison with glass jugs and its lack of fragility in the shipping process. Previously, milk jugs could shatter during shipping and make a mess that cost money and time to clean, and worse – wasted product.

Consumers agreed that the weight and flexibility of storage made plastic containers more attractive. But until the mid-70s, plastic milk bags lagged in sales behind plastic milk jugs. This would change as it rode the wave of another revolution.

The milk bag reaching Canadian markets coincided with a major shift throughout the country, which likely helped it gain the necessary support to survive. In the 70s Canada would move from the imperial measurement system to the metric system.

This put manufacturers in the position to have to reconsider their approaches to packaging and container sizes, needing to adjust according to the new system of measurement. Products would need to be measured in litres, not pounds.

Photo credit: Uliana Kopanytsia

Since turning a gallon milk bag into a litre milk bag just meant cutting the plastic in a different spot, it was a quick solution. Turning a gallon glass, plastic or gable-topped cardboard jug into a litre glass, plastic or gable-topped cardboard jug meant having to manufacture completely new containers.

It was more cost effective and convenient to businesses to manufacture plastic milk bags so it caught on and stuck mainly throughout one half of the country. By 1983, nearly all Ontario manufacturers had made the leap to plastic milk bags.

Milk bag hacks

Milk bags soon became affordable and convenient favourites in Eastern Canada. The bags are stackable in fridges with tight shelves or to fill spots where an upright jug would not fit. Additionally, milk bags saved packaging waste. The amount of plastic required to create a four-litre milk bag can be up to 75 per cent less than what would be required to create a 4-litre plastic jug. But it took a little bit of time and practice to catch on.

The milk bag meant consumers had to try new techniques to home dairy management.

The most common way to use a milk bag in Canada requires the consumer to purchase a special reusable pitcher. These look like narrow, plastic jugs with an open top. The basic plastic milk pitcher has not changed much since the 1970s, although there are some industrial design companies that take it in new aesthetic directions.



You place one of the three individual milk bags inside the pitcher with the corner tips of the milk bag facing the pour spot and the handle. Then you take scissors or a knife and snip a little triangle at the corner by the spout.

The subtle art of cutting a milk bag triangle is something that comes with experience – trial and error. If you cut the triangle too small it could leave the milk bag tipping over and spilling. If you cut it too big it could pour too fast.

An advanced approach to improve the pouring capacity of the milk is to cut an extra hole on the other side of the milk bag. But this could speed up spoilage timelines, so it is a fine line to balance.

Some quite recent, innovative pitcher designs actually have a built-in blade to cut open the milk bag. The UK-originated Jugit is one such pitcher. There is also an Israeli-originated pitcher called the Kankomat that was created in 2008. Brothers Shimon and Yitzchak Cohen of Tiberias came up with the name by combining the words “kankan,” which means container and “automatic.”

There is also a magnetic safety tool called The Snippit which can be clipped to the side of the milk jug or fridge. This is a Canadian invention from 1978 that is still sold today and was intended for children to use in order to open milk bags without risking cutting themselves on a knife or scissors. It looks like a brightly-coloured, plastic toy wrench with a tiny blade tucked into a centre crease.

The inventor, John Ostrovsky of Etobicoke, thought up the concept when he had a nightmare about his son getting hurt from scissors left out from cutting milk bags. He quit his job as a civil engineer and created The Snippit, which is now sold through the company Tangibles and was originally sold mainly through Home Hardware and K-Mart.

With or without a secondary milk bag cutting tool, there is no lid. Since the milk bag will have one or two holes cut into it once opened, it can be difficult to store. Some families will just leave the holes open and make sure to drink the whole milk bag as quickly as possible, always keeping it refrigerated, while others will fold or roll the plastic down.

Others will use chip clips or binder clips – and sometimes even elastics – to keep it shut.



Milk bags around the world

While Canada has been laughed at for decades by its southern or overseas neighbours for selling milk in bags to the general residential consumer, the concept has been catching on over the years. All across the world.

The occasional dairy company in the US now sells milk in bags, as do some places in Mexico, Israel, India, South Africa, Argentina and Hungary.

Over the last two decades, even England dairy companies Waitrose and Sainsbury started selling milk in bags.

Now we just need more environmentally-friendly versions of the milk bag.

Until then, it seems the glass bottle and the biodegradable cardboard containers are making a come-back as the prime choice of packaging for the ecologically-conscious or those willing to spend a little more money to support less plastics on the planet.