Will this serum weigh down fine or low-porosity hair, and can it help define curls without stiffness?

The source explicitly states this serum is often chosen by those who want nourishment with a lighter finish and less risk of weighing the hair down compared with heavier hair oils. For fine or low-porosity hair that easily looks limp, the thin-layer spread of a serum is advantageous — it coats the fibre without building up a thick occlusive film.

For curls, the product is listed as suitable when extra definition is needed without a stiff finish. Apply to damp curls after your usual leave-in conditioner or cream, using the praying-hands method or scrunching upward. The sea buckthorn oil content helps soften the fibre and reduce the rough feel that can make curls frizz, while the serum base keeps the texture touchable rather than crunchy.

If you have very low-porosity hair, ensure the hair is thoroughly damp (not soaking) so the serum can penetrate the slightly raised cuticle. Avoid layering multiple heavy products underneath; a lightweight hydrating spray or leave-in is sufficient before the serum.