Rewritten September 24, 2026
Hair that shone at 25 often looks flatter at 50. It is easy to assume the hair itself has aged. It has not: what has changed is the hair your scalp is now making, and a couple of habits that stayed the same while everything else moved on.
Your hair is not older. Your follicles are.
A single strand is only as old as it is long. Hair grows about half an inch a month, so the ends of shoulder-length hair are roughly two years old whether you are 25 or 70. What changes with age is the follicle, the small organ in the scalp that makes each strand, and the skin around it. The hair coming out today is different from the hair it made twenty years ago.
That matters for shine, because shine is not a measure of health. It is an optical effect: a white reflection off the surface of the hair, standing out against the softer glow that comes back from inside it. Anything that weakens that contrast makes hair look duller. How shine works, with diagrams →
Five things that change with age
1. Grey hair reflects light differently
This is the largest and best understood change. Grey and white hair has no melanin, so light that enters the strand is barely absorbed and comes back out as a bright, even glow. The surface reflection is still there, but it is lost against that glow. A head of mixed grey and pigmented hair adds a second problem: each strand returns light differently, so no single band of shine forms.
2. Hair becomes wavier
Many people find that hair which was straight becomes irregularly wavy from middle age, and hair-care researchers have reported this change, particularly in women. Shine depends on strands lying parallel so that their reflections line up into one band. Irregular waves scatter it.
3. Strands become finer, and fewer
Hair diameter generally decreases in later decades, and density falls, with hormonal change around menopause playing a part for many women. Fewer, finer strands give light less of a continuous surface to reflect from.
4. The scalp makes less oil, especially for women
In women, sebum output falls noticeably after menopause; in men it changes much less into old age. A little sebum spreading along the hair smooths the surface and reduces friction. With less of it, and with wavier hair that sebum travels along less easily, the lengths spend more time dry.
5. Colouring becomes more frequent
This one is a habit rather than biology. As grey increases, the regrowth shows sooner, and most people colour more often. With a peroxide dye, each application oxidises some of the bonds that hold keratin together into cysteic acid, a change that does not revert. The more often colour is pulled through the lengths, the more of that change the ends collect. What peroxide does to the protein →
What you can change
The first four are the follicle’s and the scalp’s doing. What you can change is how you respond to them.
- Grey hair
- Increasing waviness
- Finer, fewer strands
- Less oil from the scalp
- How you wash, now that your scalp makes less oil
- What you colour with, and how often it reaches your ends
How you wash
Many people, women especially, are still washing the way they did at 25: the same shampoo, as often, worked through the full length. That made sense when the scalp was producing more oil to replace what was washed away. With less sebum, the same routine leaves hair without it for longer. We have not seen a study that tests this directly on older hair, so treat it as a reasonable inference rather than a finding. It is also easy to try.
Wash a little less often if your scalp allows it, use less product, and concentrate shampoo on the scalp. The rinse carries enough through the lengths without scrubbing them. Give it a few weeks before you judge the result.
A note about our own product: our Shampoo Bar is a true soap, and soap cleans thoroughly. It is not a gentler way to wash in this sense. If you use it, the same advice applies, and follow it with an acidic rinse such as our Hair Treatment Powder.
What you colour with
Two changes help here, and the first costs nothing.
If you use a peroxide dye, apply it to the regrowth only. Pulling colour through the lengths at every appointment is the step that repeats the damage on hair that has already been through it.
The second is to colour with something that does not make that change at all. Radico is plant colour for grey hair, made from certified organic herbs. There is no peroxide, ammonia or alkali in it, so nothing in it is there to oxidise keratin or lift the cuticle.
It also has limits worth knowing before you buy: it cannot lighten, grey takes it a shade lighter and warmer than the rest of your hair, and results on hair that has been bleached or permed are harder to predict. Patch test 48 hours before every new shade. How to choose a shade for grey →
A darker result will probably make grey hair look glossier. That is the contrast effect from the first point, not a sign that anything has been repaired, and we would rather you knew which it is.
What we have not measured
We have not measured the shine of hair coloured with Radico, or compared older hair washed in different ways. The five changes above come from published research on hair in general, listed below. The washing advice is our inference from them, and we have said so where it applies.
Plant colour is not a treatment. It will not make hair grow, thicken it, or slow greying, and it will not undo damage already in the ends. Hair is dead tissue with no way to repair itself. What you can influence is what the new growth goes through from here.
If you are unsure whether plant colour will suit your hair, send a photo to customer-service@radicousa.com. We will tell you honestly, including when the answer is no. See the shades →
References
Reich C, Robbins CR. Light scattering and shine measurements of human hair: a sensitive probe of the hair surface. J Soc Cosmet Chem. 1993;44:221–234.
Pochi PE, Strauss JS, Downing DT. Age-related changes in sebaceous gland activity. J Invest Dermatol. 1979;73(1):108–111.
Trüeb RM. Aging of hair. J Cosmet Dermatol. 2005;4:60–72.
Robbins CR. Chemical and Physical Behavior of Human Hair. 5th ed. Springer; 2012.
American Academy of Dermatology. Tips for healthy hair. aad.org.
None of these sources involve Radico or plant colour.