Sustainable beauty packaging

7 min read

#BlueBeauty Series: A deep dive into glass v plastic for sustainable beauty packaging

Humans have created 8.3 billion metric tons of plastic since we began producing it in the early 1950s, most of which now remains in our landfills and in the natural environment.

We all know we have an issue with plastic pollution, and it is everyone's responsibility to cut down on our use of plastic.

But what about glass? Is glass actually any better?

Thinking about whether glass or plastic is "better" for the environment is not straightforward and we need to look at lots of different factors to work out which we should use.

Bolt Beauty - eco friendly skincare

We need to think about:

  1. The raw materials used in their manufacture, and any harm caused during their extraction.
  2. The energy used in the manufacturing process.
  3. The environmental impact of transporting the packaging to the factories and onwards to the consumer.
  4. Can it be recycled, do people actually recycle and how many times can it be recycled?
  5. Is it a "product for life", or does it have a "single use and dispose" function.

And it's not even as simple as that. There are lots of additional complications which arise from:

  • The global location of raw materials.
  • The different carbon intensities of the electrical generation used in manufacture in individual countries. (Some countries use much more efficient and/or "cleaner" energy compared with other countries, so it makes a difference where something is made and what the energy infrastructure is like there.)
  • The increasingly long global supply chains that result in significant "transport miles".
  • The availability of recycling facilities.
  • The actual recycling rates achieved.

Confusing, huh? So which one is better? Let's take a look at the pros and cons of using glass and plastic for product packaging.

1. What raw materials are used to make glass or plastic?


Glass is made from all-natural resources, such as sand, soda ash, limestone and recycled glass.

Only a specific kind of sand can be used to make glass (no, desert sand can’t be used). Sand is mostly harvested from riverbeds and seabeds - and we’re running out. Worldwide, we go through50 billion tons of sand every year. That is twice the amount produced by every river in the world.

Taking sand out of the natural environment also disrupts the ecosystem affecting microorganisms that live on it and which feed the base of the food chain.

Removing sand from the seabed also leaves coastal communities open to flooding and erosion.

Limestone quarrying is also associated with habitat loss and scarring of the landscape.


The major raw materials used to manufacture plastic are oil and natural gas which are treated in a “cracking process” to convert them into hydrocarbon monomers, such as ethylene and propylene. These monomers are then chemically bonded into chains called polymers. The different combinations of monomers yield various different kinds of plastics, all with a wide range of characteristics and properties.

The extraction of hydrocarbons (oil and gas) from the earth is energy and resource intensive and has the potential to create major environmental impacts from leakage, spillage and emissions released during the processing processes, and potential impacts on marine life for offshore production.


2. How much energy (and resulting carbon footprint) does it take to make glass or plastic?


Once the raw materials are harvested, they are sent to a furnace for energy intensive melting where they’re heated to 2600 to 2800 degrees Fahrenheit. Afterwards, the raw glass goes through further conditioning, forming and finishing processes - again energy intensive - before becoming the final product.

The energy required to power the glass furnaces and product manufacture is a substantial component of the environmental impact of glass. That energy is primarily oil and natural gas.


The production of plastic relies on oil and gas as a base material. The process it takes to create plastic packaging is less energy intense than the production of its glass counterpart, meaning that plastic has a smaller carbon footprint than glass.

Even though plastic uses oil and gas as its main raw materials, this does not have a carbon impact (other than the limited energy it takes to turn the these materials into plastic). In other words, in creating plastic, the potential carbon impact of the oil and gas contained in the plastic has not yet been realised - it's sitting there in plastic form but is not released into the environment. If the plastic packaging stays as plastic (even in waste form) it won't "release" any carbon. However, if plastic goes to incineration as part of the waste disposal process, the carbon contained in the oil and gas that made the plastic will be released. Burning plastic releases these emissions from the plastic product.

Whether the product is made from virgin materials or recycled content is also a significant factor - it takes 75% less energy to make a plastic bottle from recycled plastic compared with using 'virgin' materials.

To show how close and variable the results are in terms of the energy it takes to create plastic and glass packaging, a detailed study comparing wine bottles in the UK in either glass (standard weight and light weight) or PET bottles (PET is short for polyethylene terephthalate and is a common form of plastic), gave the following results.

(These results are UK specific and take into account the average recycled rate of the raw materials (plastic and glass) in the UK, and the UK energy intensity rate.)

The manufacture of a 54g virgin PET bottle (size of a plastic wine bottle) releases 222g CO2.

The manufacture of a 496g glass bottle (a normal weight wine bottle) releases 293 gCO2.

The manufacture of a 365g glass bottle (the light weight wine bottle) releases 216 gCO2.

3. What's the environmental impact of transporting the glass or plastic packaging around the world?

(It's really important to remember that business's supply chains can be really long and complicated. We live in a world where raw materials and products need to be shipped across continents as part of their manufacture and sale.)


Glass is heavier than plastic, and breaks much easier during transit. This means it produces substantially more emissions in transportation than plastic, and costs more to transport.


For short distances, plastic bottles have a low transportation footprint. They pack tightly — companies are definitely responding to greener consumers and are keeping sustainability in mind when designing the shapes of their bottles. They’re also very lightweight, so shipping them consumes less fuel.

The environmental impact from wastage caused by breakages is also minimal.

A 500ml glass bottle weighs about 400g, but a comparable 500ml PET bottle, carton or aluminium weighs about 10g.

While that might add up to a little annoyance for you as a consumer, that 40 to 1 weight ratio is a very big problem for manufacturers and distributors. It means more wear and tear on packaging machinery, less efficient shipping and distribution, and, as a result, higher fuel costs and emission responsibility.

4. What happens to glass or plastic once we've used the packaging?


Glass is endlessly recyclable, back to its original use. It never loses its quality and purity, no matter how many times it’s recycled…. but is it actually being recycled?

Unfortunately not - most glass isn’t actually recycled. In fact, only 33 percent of waste glass is recycled in America. The rest goes to a landfill.

There are many reasons glass recycling is so low:

  • Glass put into the recycling bin is used as a cheap landfill cover to keep costs low;
  • Consumers engage in “wish-cycling” where they toss non-recyclables into the recycling bin and contaminate the entire bin;
  • Coloured glass can only be recycled and melted down with like-colors;
  • Windows and Pyrex bakeware are not recyclable because of the way it’s manufactured to withstand high temperatures.


Plastic can only be recycled so many times. In fact, it’s technically downcycled into a lesser quality item, meaning it can never be the same thing more than once. Eventually, it becomes unrecyclable altogether and ends up as a waste product.

Only 9 percent of plastic is actually recycled. Humans have created 8.5 billion metric tons of plastics since large-scale production began in the 1950s, and most of it is in a landfill or our environment.

It should also be noted that plastic takes a very long time to disintegrate and break down. A plastic bottle for example, takes450+ years to disintegrate, and a thousand years if they’re in a landfill.

Even after you dispose of plastic, be it through dumping, incinerating, recycling and composting (for certain bio-plastics), all release carbon dioxide. The emissions from plastics in 2015 were equivalent to nearly1.8 billion metric tons ofcarbon.

So, which one is more sustainable?

Both glass and plastic packaging create an environmental impact during their manufacture, transport, use and disposal.

Lots of us assume that glass is more sustainable, but, various factors like supply chains, manufacture and recycling levels all complicate this. To get a definitive answer, you need to do a detailed Life Cycle Analysis (LCA) for the specific product and its particular supply chain. A blanket answer is impossible and it really does depend on each product and its supply chain and use.

It's not always the case that glass is more eco-friendly. We need to be more thoughtful and critical when it comes to our packaging choices and not just assume glass is better.The best thing we can do to minimise our personal environmental impact is to reduce our reliance on anything single-use.


The real answer: move away from a “buy, use and dispose” model.

In an ideal world, we would have products which provide a storage for life system, with product replenishment that removes all single-use plastic or glass completely. This is known as "circular packaging" (because we carry on using the original jar continuously and never need a new one).

Bolt Beauty uses circular packaging. Our biodegradable skincare capsules can be purchased in a "jar for life" and then replenishment capsules come in fully compostable refill bags*. As a carbon neutral company, we use PET "jars for life" as the carbon impact is lower when compared to a glass alternative.

Just think of how many single use plastic or glass bottles or jars are used for skincare (and we need to buy them over and over again)... *shudders*.If we can all move to a refill system just for a part of our beauty regime we can make a real difference to the waste problem.


* We're really sorry that our Refill Bags have been delayed due to manufacturing being impacted by Covid-19. The safety of our team and supply chain are our first concern and so we made the tough decision to pause their production. We are working on it though and hope to launch these in summer 2020.

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