Why controlled
temperature
matters.
Cold therapy uses a controlled temperature window. Frozen packs can begin far below it and then warm straight through it. Kelvin® is designed to settle into a gentle 10 to 12°C as it slowly warms.
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A useful range for
controlled cooling.
The published evidence describes a useful cold-therapy range. Starting colder does not mean staying in that range.
Colder temperatures bring rising risk, including ice-burn and the protective cold rebound first described by Lewis.
Algafly and George reported that cooling skin to about 10°C reduced nerve conduction velocity by about a third.
As temperature rises, it moves beyond the range commonly used for cold therapy.
Go colder and you get diminishing returns and rising risk.
Sir Thomas Lewis described a protective response in which blood vessels periodically open and warm blood returns to an area exposed to intense cold.
Heart, 1930
Kelvin® is designed to hold a gentle 10 to 12°C as it slowly warms, rather than beginning at around -15°C, the sub-zero temperature of a frozen pack.
A long-established physiological responseWhy colder is not always better.
- 01stage
Cold shock
A frozen pack begins at around -15°C, far too cold at first contact, creating an intense cold shock.
- 02stage
Vessel response
The body constricts local blood vessels in response to intense cold.
- 03stage
Cold rebound
Lewis described a protective response where blood vessels periodically open and warm blood returns to the cooled area.
Sir Thomas Lewis, Heart, 1930
- 04stage
Warming through
As an ice pack thaws, its temperature keeps changing instead of holding one controlled range.
Kelvin® never goes sub-zero. It is designed to avoid the ice-burn and cold-shock of a pack that starts at around -15°C, while providing steady cooling comfort.
Temperature across a session.
This illustrative profile shows the principle: an ice pack starts too cold and warms through the useful range, while Kelvin® is designed to settle into it. Independent thermal testing is underway; results will be published here.
Illustrative, based on our own thermal testing. A frozen pack sits sub-zero, an ice-burn risk, before slowly warming past the useful range; Kelvin® stays in the controlled cold-therapy window. Independent thermal testing is underway and measured figures will be published here when it is complete.
Latent heat,
not sensible heat.
A standard gel pack stores sensible heat - its temperature climbs steadily as it absorbs energy from the body.
A phase-change material stores latent heat. It absorbs energy by changing phase at about 10 to 12°C, helping the pad hold a gentle, controlled temperature as it slowly warms.
When the phase change completes, you put it back in the fridge. The material re-sets. You use it again. There is no consumable. There is no waste.
The reading.
- 01Algafly AA, George KP (2007). The effect of cryotherapy on nerve conduction velocity, pain threshold and pain tolerance. British Journal of Sports Medicine, 41(6), 365-369. PMID 17224445.
- 02Lewis T. (1930). Observations upon the reactions of the vessels of the human skin to cold. Heart, 15, 177-208.