Beauty Packaging: What is the “right” material, and what is the “wrong” one? What about glass?

In an article published at the end of June, Gérald Martines* discussed replacing plastic with other materials in order to reduce plastic pollution.
It is clear that efforts to reduce/eliminate plastic pollution are justified. But are the alternative solutions currently being implemented as virtuous as we think?
For Gérald Martines, “the idea is certainly not to denigrate any particular material, but rather to consider the problem of their use as a whole, without resorting to misleading shortcuts.” According to him, "there is no such thing as a ‘good’ or ‘bad’ material for packaging. Each has its own advantages and limitations. Choosing a packaging system is a matter of weighing up imperfect solutions, where we are reduced to choosing ‘the least bad’ option and giving up on finding THE right one."
The aim of this new series of articles is to help you make more informed choices, rather than giving in to fashion trends or relying on a reputation that may not fully reflect reality.

Today, it’s “glass’s turn”!

Glass is rightly considered the aristocrat of packaging; it is the luxury material par excellence.
It is known to be infinitely recyclable (and is indeed recycled at a high rate in most developed economies: 80% in the EU, 88% in France, 99% in Sweden, vs. 24 to 63% in the US, depending on the state). Properly designed glass containers are durable and can be reused multiple times through deposit and refill systems. It therefore enjoys a very positive image as a “circular,” “sustainable,” and “virtuous” material.
However, the manufacture of glass packaging requires a very large amount of energy: it must be melted at temperatures of around 1600°C.
Once molded, it must be “annealed” for several hours at around 600°C to eliminate internal stresses caused by the sudden cooling during molding.
As a result, energy typically accounts for three-quarters of the carbon footprint of a bottle [1] or glass jar, compared to one-quarter for raw materials.
And although the material is recovered during recycling, almost the same amount of energy must be consumed again for a recycled object [2].
This results in a high carbon footprint, even for recycled glass.
This carbon footprint depends on the energy mix used for the furnace and annealing ovens. Traditional furnaces and ovens, heated with natural gas, emit large amounts of CO2 and thus contribute to global warming. For electric furnaces, their emissions depend on the local electricity mix; the same furnace will emit four times less CO2 in France than in Germany, because the former has one of the lowest carbon electricity mixes in the world due to the high proportion of nuclear and hydroelectric power, while in the latter, the mix is still dominated by coal, the most CO2-intensive source of electricity [3].
Of course, manufacturers can purchase electricity from renewable sources and thus announce a superficial reduction in their carbon footprint. However, this argument should be considered carefully: at any given moment, the amount of renewable electricity available is finite, and what is consumed by one player is no longer available to the rest of the community. Ultimately, the overall balance for the community is in no way improved by the fact that one player rather than another uses the available share of carbon-free energy.
Finally, it should be noted that the forced electrification of industry and transport (which is one of the conditions for reducing emissions to which states committed in the Paris Agreement to limit the effects of the climate crisis) is putting very strong pressure on the electricity production and distribution infrastructure, which will be one of the greatest industrial and economic challenges we will have to manage in the near future.
Other alternative solutions are also being tested to reduce furnace emissions: biogas, hydrogen, and hybrid furnaces; oxy-combustion (using oxygen rather than air as a combustion agent), etc. These efforts are to be commended, but all these solutions come up against a stubborn physical reality: glass, whether virgin or recycled, remains very energy-intensive.

Energy-intensive, fragile, and infinitely recyclable—it’s a misleading promise!

A second limitation of glass is its intrinsic fragility, which requires packaging to be designed with thicker walls than for other materials, thereby increasing the weight of the packaging, all other things being equal. This fragility also means that packaging must be designed to be more protective and bulkier than for other materials, which increases logistics costs and transport emissions.
Let’s now consider the argument of “infinite” recyclability. What seems like an ideal promise of circularity actually hides a more nuanced industrial reality. In terms of recycling, we can only physically perform “downcycling,” with each stage of recycling deteriorating the aesthetic qualities of the glass through the accumulation of impurities and metal oxides that color the glass. Thus, depending on the requirements of beauty brands, between 15 and 40% of post-consumer recycled glass can be incorporated to remain in the “extra-white” glass category. By comparison, in a beer bottle, typically green or amber, the percentage of recycled glass can reach 95%.
Claiming that a luxury bottle is recyclable actually means “recyclable for another application that is less demanding than a perfume bottle,” and we are far from a closed-loop system.
And, like any industrial process, recycling is not 100% efficient; not everything that is sorted is recycled: some of the glass volume is lost in the form of dust and particles that are too small to be captured. In addition, lacquered or metallized bottles are not recognized as glass by optical sorting systems and end up in landfills. As for body-tinted glass, it obviously cannot be recycled into white glass.
Glass therefore constitutes an open downcycling chain: at the top of this chain is extra-white glass, which is used to make luxury items, then as the ‘recycling’ cycles progress, the glass becomes cloudy and tinted and can only be used for less and less demanding applications, until it ends up at the bottom of the chain as filler for road surfacing, as backfill, or even in landfill. Ultimately, a constant flow of virgin material is needed to feed this entire open chain, i.e., to compensate for all losses, in addition to meeting the increase in demand.
The total amount of post-consumer recycled (PCR) glass available is therefore finite at any given time and lower than the overall demand for glass, raising the question of how it should be distributed among the various players. Until recently, the situation was simple: at the top of the chain, extra-white glass was produced from virgin material [4], then PCR glass was gradually introduced further down the downcycling chain, with beer bottle producers being the largest users. With growing demand from consumers, and therefore brands, for ‘low-carbon’ luxury bottles, glassmakers have worked to introduce a proportion of PCR glass into their formulations. This cullet is obviously taken, after rigorous sorting, from the total amount available globally, thus ‘depriving’ other players. This creates a paradoxical situation where luxury goods monopolize a portion of PCR glass that less noble applications must replace with virgin material. Here again, the fact that one player rather than another uses the available finished PCR does not improve the overall balance for the community—in fact, in this case, it worsens it, because the sorting required to select the most valuable glass cullet represents a net additional cost and an incremental energy expenditure.
You might think that sand is a very common and abundant material? Unfortunately not, because sand suitable for making extra-white glass must have very low metal oxide content, and few quarries offer this quality. In addition, there is strong competition for sand: it is also consumed in huge quantities by the construction industry, boosted by global urban development. Sand is also needed for the tech industry, as the chips at the heart of all our gadgets are made of silicon, which is extracted from sand...
Never mind, with all the deserts on the planet, whose surface area is inexorably increasing under the pressure of human use and global warming, we’re not about to run out of sand, are we? Not at all! Regardless of the questionable nature of the idea of siphoning off the dunes of the Sahara to feed our thirst for consumption, this sand, which is very rich in iron oxides, would produce a naturally green-colored glass, culturally acceptable for wine or beer bottles but far from the extra-white glass required by the luxury industry. And worn down by the wind, its round grains are just as unsuitable for construction: Dubai, which cannot be accused of lacking sand, had to import sand from Australia for the construction of the Burj Khalifa tower.
We must face the facts: sand is by no means a renewable resource, and its finite supply is already showing signs of depletion.

The influence of “sets of defects”

The glass manufacturing process inevitably generates defects in appearance: bubbles (known as “boils”), inclusions, glazes, leeches... the list is long. A range of ‘acceptable’ defects is therefore negotiated between brands and glassmakers, resulting in a typical rejection rate of around 30 to 40% for luxury bottles, which can easily rise even higher. This means that three to four out of every 10 bottles never even leave the factory, are broken, and become internal cullet(4).
The level of acceptability of these defects is purely subjective, and each brand has its own requirements. Are they all justified? Who can say? In any case, brands wishing to reduce their environmental footprint would have a simple and immediate source of reduction at their disposal, requiring no technological innovation or investment, and moreover a source of savings. One could argue that luxury comes at this price... or even more! The perception of what luxury is is changing, and “defects” are becoming increasingly acceptable, even desirable: some cultures even value defects as a sign of uniqueness.

Choosing between pollution and global warming!

In conclusion, when a brand chooses glass over plastic, it is consciously or unconsciously arbitrating between pollution and global warming. Plastic has a reputation for polluting the environment, but glass exacerbates climate change. Neither solution is renewable (except for bioplastics, which are in the minority) and neither is circular, although glass is recycled to a greater extent than plastics.
This shows that we cannot rely on a single criterion to evaluate a material, but must adopt a multi-criteria approach, with LCA (life cycle assessment) being the ideal way to obtain an overall assessment, although its application is currently limited by the cost and complexity of its implementation. And even if we had a complete and accurate multi-criteria assessment, we would still have to arbitrate between positions that operate on non-equivalent criteria: is it better to reduce pollution at the cost of exacerbating global warming, or the opposite? There is no scientific way to decide. Finally, as no industry operates in isolation, everything interacts and luxury competes with less noble applications for the sourcing of its materials and energy.
Ultimately, the responsibility for all these choices lies with each individual player.
In conclusion, we can already establish a few best practices:
• Favor glass for sustainable applications (deposit, refillability, etc.), as its high carbon footprint is then offset by the number of uses.
• On the other hand, using it for single-use applications is counterproductive, as this increases energy consumption and CO2 emissions.
• Aim for maximum packaging reduction: attitudes are changing, and heavy weight, traditionally considered a marker of luxury, is beginning to be seen as unacceptable waste.
• In this context, design plays a role: the closer a package is to a sphere, the more “efficient” it is in terms of the content/container ratio, and it also requires less thickness. Conversely, very angular shapes are inefficient.
• Prefer the largest possible formats, which minimize the amount of packaging vs. the amount of product; this recommendation goes against the trend of mini formats...
• Design packaging for optimal recycling at the end of its life by avoiding opaque decorations and inseparable accessories.
• Define sets of “reasonable” defects.
• Incorporating PCR is purely a marketing ploy that does nothing to improve the world’s overall balance sheet.
Will we see a profound change in the use of glass in packaging? Only time will tell, but the pressure for more responsible use is already noticeable and will only intensify.

Gérald Martines - IN-SIGNES

*Gérald Martines founded IN•SIGNES to provide companies in the beauty and luxury sector with a wealth of experience in innovation, sustainable development, and business development, gained from 30 years of working in marketing, design, R&D, sales, and general management roles in several international groups that are leaders in the beauty and design industry.
With a master’s degree in physics, a degree in mechanical engineering, a postgraduate degree in materials science, an MBA, and a master’s degree in foresight, Gérald Martines has a 360° view of the various professions, skills, and functions that contribute to strategic thinking.

Notes: The figures given below are indicative orders of magnitude; actual figures may vary depending on the specific cases considered – sources: In•Signes research and calculations.