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Do beer Koozies work?

So does putting some foam rubber around your drink work - and is it actually worth it? On the face of it you might be inclined to say yes, the idea is that it should insulate the drink from the outside air (and thus keep the cold in), but interest of science we've commissioned some research to give the definitive answer to 'Do Koozies actually work?'.

Performance and properties of commonly used drink insulators

Darren. J. Tillett B. Sc. (Eng.) Ph. D.


Drink insulators, also known as 'beer Koozies' (Kozys, Cosys, Coozies, Stubby holders (AUS)) are commonly used products to insulate refrigerated canned and bottled beverages from the effects of radiant and conducted heat. Materials used in their contruction include Neoprene (polychloroprene), EVA (ethylene vinyl acetate) and polystyrene foams. This foam insulating layer is usually a thin (3 - 5mm) layer and is often laminated with a fabric (usually polyester based) or polymeric printed layer on the outside. This article determines the performance and properties of the more common types of drink insulators available.


Five test groups were meaured against a control sample: a 4mm EVA (approx 80kg/m3 density) insulator (without base), 5mm neoprene (approx. 96kg/m3) with inserted base, 4mm Neoprene (with cut-out base) and 3mm Neoprene (with cut-out base).

Two sets of experiments were performed, one using 37.5cl cans and another with 33cl bottles (green glass).

All containers were chilled to 2°C before filling and each was filled with 300ml of iced, distilled water chilled to 2°C.

Once stabilised containers were placed quickly into their respective 'Koozie' insulator and a starting measurement taken immediately afterwards.

Subsequent temperature measurements were taken at three minute intervals. Immediately prior to temperature measurement each sample was stirred vigorously to eliminate temperature gradients with the vessel due to convection. Three replicants of each group were measured and results averaged.

Three seperate experiments were performed: one with canned beverages in the absence of a radiant heat source in an ambient temperature of 25°C. The second was performed with canned beverages in the presence of strong, uninterupted sunlight and an ambient temperature of 30°C. The final experiement was performed using glass bottles in the presence of strong, uninterupted sunlight and an ambient temperature of 30°C.


1. Conduction of heat into canned beverages with and without insulating 'Koozies'. Ambient temperature : 25°C

Koozies Insulation Performance: Conduction

2. Conduction and Infrared heat absorption into canned beverages with and without 'Koozies'. Ambient temperature : 30°C

Koozies Insulation Performance: Conduction

3. Conduction and Infrared heat absorption into bottled beverages with and without 'Koozies'. Ambient temperature : 30°C

Koozies Insulation Performance: Conduction


It is clear from the research presented that 'Koozies' absolutely do insulate liquids contained in both cans and bottles from both heat in the air (via conduction) and infrared heat from the solar radiation.

All the figure above show that EVA foams perform marginally better than neoprene foams as is to be expected as EVA has a lower value of thermal conductivity (0.033 - 0.05 W/mK compared to 0.15–0.45W/mK). It can also be seen from Figures 2 and 3 that the fabric color of the 5mm Neoprene 'Koozie' has a limited, but distinct effect on its abilities to insulate the beverage in the presence of an infrared heat source - again, this is to be expected.

Figure 2 shows that a drink insulated by a 4mm EVA Koozie warms 50% more slowly in direct sunlight (0.33°C per minute compared to 0.66°C per minute of the control can).

From Figures 2 and 3 it can be seen that canned beverages are less affected by radiant heat sources than bottles. This is due to the extra height of uninsulated glass and the ability of the sunlight to directly heat the liquid via transmission of infrared radiation through the glass walls of the container.

Figure 3 also shows that a thinner Neoprene insulator (3mm) has a nearly equal performance to the thicker 5mm Neoprene insulator. We believe this is due to the fact that the 3mm did not tighly fit the bottle leaving an air gap. This air gap provided equal insulation for the liquid in the bottle than almost 2mm of neoprene foam.

The temperature that some fermented beverages are consumed (both beer and wine) is purported to be of great importance to the sensory experience of the consumer. This range is described for many fermented alcoholic drinks to be between 2°C (ice cold) and 11°C (cellar temperature). It can clearly be seen above that 'Koozies' are able to keep a chilled beverage within a certain temperature range for longer than one that is not insulated.

From Figure 1 it can be said that using a 'Koozie' extends the period of time that a drink it at its optimal temperature from just 12 minutes to 30 minutes or more. In sunlight the warming of an uninsulated drink is markedly quicker - being above 11°C within just 9 minutes, but even a bottled drink with a 'Koozie' can keep a the liquid within the ideal range for 20 minutes (Figure 3).


Drink insulators (or beer 'Koozies') lower the rate of heating for liquids contained in both cans and bottle by conducted and radiant heat markedly thus improve the amount of time where the sensory experience of consumption of the liquid contained within is optimal. The best combination to extend this range is a light colored EVA foam (preferably white) with little or no print that is insulating a canned beverage.

Read Our Interpretations of the these results in detail here: Do Koozies Work Part II: What is the best temperature to serve beer?

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