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14 Nov 2024
By Fe Skiniora
Why We Test for Eighteen Months Before Anything Ships
Stability testing is the least visible part of making skincare and the part that decides whether what you buy still works in month nine. An account of what happens in the meantime.
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A formula that works on the day it is mixed is not a product. It is a promising start. What matters is whether it still works after it has spent four months in a warehouse, three weeks in a shipping container in July, and two months on a shelf in a bathroom with a shower running twice a day.
Most of what goes wrong in that window is invisible. Actives quietly lose potency. Emulsions separate at a microscopic level long before you can see it. Preservative systems get overwhelmed. None of this shows up in a two-week trial, which is why we run eighteen months before anything is offered for sale.
What Those Months Contain
Months one to three: accelerated ageing
Samples are held at raised temperatures to compress time. If a formula is going to separate, this is usually where it admits it.
Months four to nine: real time, real conditions
Parallel batches sit at room temperature, in the fridge, and through repeated freeze-thaw cycles. Anything that behaves differently across the three is reformulated rather than adjusted.
Months ten to fourteen: challenge testing
The preservative system is deliberately attacked to confirm it holds after a bottle has been opened, touched and left in a humid room.
Months fifteen to eighteen: in use
A small group uses the formula daily, in their own climates, alongside whatever else is in their routine. Nearly every late change we make comes from this stage.
Why It Is Worth Saying Out Loud
It explains why the range is small and why it grows slowly. There is no way to run this process and also launch four times a year, and we would rather explain the wait than shorten the testing.
14 Nov 2024
By Fe Skiniora
Why We Test for Eighteen Months Before Anything Ships
Stability testing is the least visible part of making skincare and the part that decides whether what you buy still works in month nine. An account of what happens in the meantime.
SHARE
A formula that works on the day it is mixed is not a product. It is a promising start. What matters is whether it still works after it has spent four months in a warehouse, three weeks in a shipping container in July, and two months on a shelf in a bathroom with a shower running twice a day.
Most of what goes wrong in that window is invisible. Actives quietly lose potency. Emulsions separate at a microscopic level long before you can see it. Preservative systems get overwhelmed. None of this shows up in a two-week trial, which is why we run eighteen months before anything is offered for sale.
What Those Months Contain
Months one to three: accelerated ageing
Samples are held at raised temperatures to compress time. If a formula is going to separate, this is usually where it admits it.
Months four to nine: real time, real conditions
Parallel batches sit at room temperature, in the fridge, and through repeated freeze-thaw cycles. Anything that behaves differently across the three is reformulated rather than adjusted.
Months ten to fourteen: challenge testing
The preservative system is deliberately attacked to confirm it holds after a bottle has been opened, touched and left in a humid room.
Months fifteen to eighteen: in use
A small group uses the formula daily, in their own climates, alongside whatever else is in their routine. Nearly every late change we make comes from this stage.
Why It Is Worth Saying Out Loud
It explains why the range is small and why it grows slowly. There is no way to run this process and also launch four times a year, and we would rather explain the wait than shorten the testing.
14 Nov 2024
By Fe Skiniora
Why We Test for Eighteen Months Before Anything Ships
Stability testing is the least visible part of making skincare and the part that decides whether what you buy still works in month nine. An account of what happens in the meantime.
SHARE
A formula that works on the day it is mixed is not a product. It is a promising start. What matters is whether it still works after it has spent four months in a warehouse, three weeks in a shipping container in July, and two months on a shelf in a bathroom with a shower running twice a day.
Most of what goes wrong in that window is invisible. Actives quietly lose potency. Emulsions separate at a microscopic level long before you can see it. Preservative systems get overwhelmed. None of this shows up in a two-week trial, which is why we run eighteen months before anything is offered for sale.
What Those Months Contain
Months one to three: accelerated ageing
Samples are held at raised temperatures to compress time. If a formula is going to separate, this is usually where it admits it.
Months four to nine: real time, real conditions
Parallel batches sit at room temperature, in the fridge, and through repeated freeze-thaw cycles. Anything that behaves differently across the three is reformulated rather than adjusted.
Months ten to fourteen: challenge testing
The preservative system is deliberately attacked to confirm it holds after a bottle has been opened, touched and left in a humid room.
Months fifteen to eighteen: in use
A small group uses the formula daily, in their own climates, alongside whatever else is in their routine. Nearly every late change we make comes from this stage.
Why It Is Worth Saying Out Loud
It explains why the range is small and why it grows slowly. There is no way to run this process and also launch four times a year, and we would rather explain the wait than shorten the testing.
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