- Format
- Leave-in hair serum
- Photographed size
- 90 ml / 3.04 fl oz
- Brand positioning
- Porous, damaged hair
The mirror-finish bottle makes this serum the most reflective object in the edit. The red K is easy to recognise; the smaller name, Sérum Filler Fondamental, tells you which product it is. The owner’s photograph shows the 90 ml bottle.
A leave-in in the Première range
Kérastase positions this serum for porous, damaged hair. The brand’s directions are straightforward: apply to towel-dried hair, leave in, then blow-dry and heat style. It also makes a heat-protection claim up to 450°F. These are the manufacturer’s directions and claims, not results from a MASSO test.
“Serum” alone is not enough to decide how to use a hair product. Whether it is rinsed out, applied before shampoo or left in for styling is the more practical distinction.
Compare the job, not just the collection
Our original OLAPLEX No.3 guide concerns a pre-shampoo treatment. Gloss Absolu Glaze Milk is another leave-in, presented by Kérastase as a smoothing spray for fine to medium hair prone to frizz. Those differences make a useful reading path through products that might otherwise become an indistinct row of bottles.
You do not need all three to make a routine look complete. Begin with the step you are considering, read its directions and decide what you would want to observe after using it.
Make the next wash day informative
The most useful comparison would keep the drying method and other styling products consistent. Notes about manageability, the finish and how much product was applied would mean more than a photograph of glossy packaging.
Keep a short note after styling: how much you used, which tools you reached for and whether the finish was the one you wanted. That gives your next choice a point of reference. The shopping link below opens the current listing; check the selected size before ordering.
Our existing ShopMy link opens Sephora’s Première Repairing Anti-Frizz Serum listing. The photographed bottle is 90 ml; check the retailer’s current size and delivery market.
Sources & further reading
- Kérastase: Première Sérum Filler Fondamental, 90 mlhttps://www.kerastase-usa.com/collections/premiere/serum-filler-heat-protecting-repairing-hair-serum.html
A life well considered.

