Bioactive Density Lash Serum
Bioactive Follicle Support, denser-looking lash line
Hybrid formulation
Bioactive Follicle Support
Density is not a second length serum. This formula leads with Acetyl Tetrapeptide-3 (Capixyl-class) and red clover, plus a Redensyl-style botanical complex (larch wood, green tea, glycine, zinc) for the look of a denser, better-anchored lash line, without prostaglandins. Once-daily, and disclosed in full.
Key actives
Acetyl Tetrapeptide-3
Acetyl Tetrapeptide-3 (Capixyl-style, paired with red clover) · Redensyl-style botanical complex (larch wood, green tea, glycine, zinc chloride) · Sodium Hyaluronate · Panthenol (provitamin B5)
- Free from Prostaglandins
- Free from Parabens
- Free from Fragrance
- Free from Sulphates
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Enquire about availabilityWho it's for
Anyone who wants a denser-looking, better-anchored lash line from botanical-bioactive follicle support, not another peptide length serum.
How to use
Apply once daily to the upper lash line.
Full ingredient disclosure (INCI)
INCI means International Nomenclature of Cosmetic Ingredients: the standard names used on cosmetic labels worldwide.
Aqua (Water), Glycerin, Propanediol, Butylene Glycol, Panthenol, Camellia Sinensis Leaf Extract, Larix Europaea Wood Extract, Glycine, Zinc Chloride, Acetyl Tetrapeptide-3, Dextran, Trifolium Pratense (Clover) Flower Extract, Rosmarinus Officinalis (Rosemary) Leaf Extract, Sodium Hyaluronate, Biotin, Sodium Metabisulfite, Hydroxyethylcellulose, Sodium Citrate, Citric Acid, Disodium EDTA, Phenoxyethanol, Ethylhexylglycerin
Test data on file
- Prostaglandin analogues
- None
- Complex
- Capixyl-class + Redensyl-style
- Use
- Once daily
Independent lab results stand behind every product, and we'll send any report on request, reference RL-BDS-003.
Built to the Ruski Standard
Acetyl Tetrapeptide-3, held to the Ruski Standard
Acetyl Tetrapeptide-3 (Ac-KGHK) is the Capixyl-class peptide associated in manufacturer data with extracellular-matrix support around the follicle, a denser-looking line story, not a prostaglandin pathway and not an MP-17 length lead. We disclose it alongside a Redensyl-style botanical complex (larch wood, green tea, glycine, zinc). Appearance outcomes depend on consistent use and individual baselines; published independent lash trials are limited, and we treat manufacturer dossiers as manufacturer data. No prostaglandin analogues. Use as directed on a clean lash line.
Read Ruski Standard
The formulation
Every ingredient earns its place. Here is each one: what it is, why it's in this formula, and what evidence supports it, including where that evidence is limited.
Water · INCI: Aqua (Water)carrier/solvent
Forms the water base that dissolves the humectants, botanical extracts and water-soluble peptide and carries them evenly along the lash line.
Established cosmetic-science consensus; water is the standard solvent base for leave-on serums.
Glycerin (vegetable glycerol) · INCI: Glycerinhumectant
Draws and holds moisture against the lash fibre so lashes stay supple and conditioned through daily wear.
Well-established cosmetic-science consensus as one of the most studied humectants.
Propanediol (1,3-propanediol) · INCI: Propanediolhumectant
A plant-derived humectant and co-solvent that hydrates, helps dissolve the actives and improves the spread and feel of the serum.
Established cosmetic-science consensus as a humectant and solvent that also supports preservative efficacy.
Butylene glycol · INCI: Butylene Glycolcarrier/solvent
A lightweight solvent and humectant that carries and helps stabilise the botanical extracts while adding light hydration.
Established cosmetic-science consensus as a humectant and botanical-extract carrier.
Panthenol (provitamin B5) · INCI: Panthenolconditioning agent
Conditions the lash fibre and helps it retain moisture, supporting a smoother, more flexible look.
Established cosmetic-science consensus for keratin conditioning and humectancy; direct peer-reviewed lash data is limited.
Green tea leaf extract · INCI: Camellia Sinensis Leaf Extractactive
Part of the Redensyl-style botanical bioactive complex; a source of green-tea polyphenols (EGCG) included to support the fuller-looking lash-line claim alongside antioxidant protection.
Green-tea polyphenol antioxidant activity is well supported in cosmetic science; its contribution to lash appearance rests mainly on the supplier complex data, and independent peer-reviewed lash evidence is limited.
Larch wood extract · INCI: Larix Europaea Wood Extractactive
The larch-derived component of the Redensyl-style complex (a source of dihydroquercetin glucoside), included to support a denser-looking lash line.
Supported chiefly by the ingredient supplier's own research programme, largely conducted on scalp hair; independent peer-reviewed evidence specific to lashes is limited.
Glycine (amino acid) · INCI: Glycineactive
A substrate amino acid that forms part of the Redensyl-style complex, completing the defined botanical bioactive system.
Its role is defined by the supplier's complex specification rather than standalone peer-reviewed lash studies.
Zinc chloride · INCI: Zinc Chlorideactive
Included as part of the Redensyl-style complex, where trace zinc completes the specified bioactive system.
Its inclusion follows the supplier's complex specification; independent peer-reviewed lash evidence is limited.
Acetyl tetrapeptide-3 (signal peptide) · INCI: Acetyl Tetrapeptide-3active
The peptide of the Capixyl-style complex, paired with red clover, included to support the look of a fuller, denser lash line.
Backed mainly by the ingredient supplier's clinical data generated on scalp hair; independent peer-reviewed evidence in lashes is limited.
Dextran (polysaccharide) · INCI: Dextrancarrier/solvent
Acts as the stabilising carrier for the peptide, keeping Acetyl Tetrapeptide-3 evenly dispersed and deliverable in the water base.
Established cosmetic-science consensus as a peptide carrier and stabiliser; it is a formulation aid rather than an active.
Red clover flower extract · INCI: Trifolium Pratense (Clover) Flower Extractactive
The botanical half of the Capixyl-style complex (a source of biochanin A), paired with Acetyl Tetrapeptide-3 to support the fuller-looking lash-line claim.
Supported mainly by the supplier's complex data on scalp hair; independent peer-reviewed lash evidence is limited.
Rosemary leaf extract · INCI: Rosmarinus Officinalis (Rosemary) Leaf Extractantioxidant
A botanical antioxidant that helps protect the formula and adds light conditioning at the lash line.
Rosemary's antioxidant activity is well documented in cosmetic use; lash-specific peer-reviewed evidence is limited.
Sodium hyaluronate (hyaluronic acid salt) · INCI: Sodium Hyaluronatehumectant
A high-capacity humectant that binds water at the lash line for lasting hydration and a conditioned, flexible feel.
Well-established cosmetic-science consensus as a moisture-binding humectant.
Biotin (vitamin B7) · INCI: Biotinconditioning agent
A vitamin cofactor included as a conditioning adjunct to complement the formula's keratin-conditioning story.
Oral-deficiency links are documented, but peer-reviewed evidence for topical biotin changing lash appearance is limited; included as a conditioning adjunct.
Sodium metabisulfite (sulfite antioxidant) · INCI: Sodium Metabisulfiteantioxidant
An antioxidant stabiliser that protects the oxidation-sensitive botanical bioactives (part of the Redensyl-style system) from degrading in the water base.
Established cosmetic-science consensus as an antioxidant stabiliser; note that sulfites can be sensitising for some people, which is distinct from the sulfates this formula is free from.
Hydroxyethylcellulose (plant-derived thickener) · INCI: Hydroxyethylcellulosethickener
A cellulose thickener that gives the serum an even, non-drip viscosity so it stays where it is brushed along the lash line.
Established cosmetic-science consensus as a non-ionic thickener and gelling agent.
Sodium citrate · INCI: Sodium CitratepH adjuster
Buffers the serum to a mild, eye-area-appropriate pH and works with citric acid to keep that pH stable.
Established cosmetic-science consensus as a buffering salt.
Citric acid · INCI: Citric AcidpH adjuster
Fine-tunes the formula to a gentle target pH suited to the lash line and to the stability of the actives.
Established cosmetic-science consensus as a pH adjuster.
Disodium EDTA (chelating agent) · INCI: Disodium EDTApreservative
A chelating agent that binds trace metal ions, protecting the botanical bioactives from metal-catalysed oxidation and supporting preservative performance.
Established cosmetic-science consensus as a chelator that improves formula stability and preservative efficacy.
Phenoxyethanolpreservative
A broad-spectrum preservative that keeps the water-based serum free of microbial growth through repeated daily use around the eye.
Established cosmetic-science consensus and regulatory acceptance, within capped use levels, as a preservative.
Ethylhexylglycerinpreservative
A preservative booster and mild conditioning agent that broadens phenoxyethanol's coverage and improves skin-feel.
Established cosmetic-science consensus as a preservative enhancer.
Sources and limitations
Manufacturer or supplier data
MModerateThe larch-wood and green-tea based complex (with glycine and zinc chloride) is reported to support hair density in the ingredient supplier's own scalp studies; this is the basis for its inclusion for a fuller-looking lash line.
Givaudan Active Beauty (Induchem) Redensyl technical and efficacy dossier
Manufacturer or supplier data
MModerateThe Acetyl Tetrapeptide-3 plus red clover (biochanin A) complex is reported to improve hair density in the ingredient supplier's clinical data conducted on scalp hair.
Lucas Meyer Cosmetics Capixyl technical and clinical dossier
Manufacturer or supplier data
EEmergingThird-party testing for the finished Bioactive Density Lash Serum is held on file under lab reference RL-BDS-003 and is available on request.
RUSKI Lashes finished-product third-party test report, lab ref RL-BDS-003
Cosmetic-science consensus
SStrongGreen-tea polyphenols such as EGCG have well-recognised antioxidant activity in topical cosmetic use.
Established cosmetic-science and dermatology consensus on green-tea polyphenol antioxidant activity
Cosmetic-science consensus
SStrongPanthenol acts as a keratin-conditioning humectant that helps retain moisture in hair and skin.
Established cosmetic-science consensus on panthenol (provitamin B5)
Cosmetic-science consensus
SStrongSodium hyaluronate is a high-capacity humectant that binds and holds water at the application site.
Established cosmetic-science consensus on sodium hyaluronate
Cosmetic-science consensus
SStrongPeer-reviewed evidence that topically applied biotin changes lash appearance is limited; biotin's documented role is chiefly in oral deficiency states.
Cosmetic-science and dermatology consensus on topical versus oral biotin
Which serum
Three serums. Three jobs.
Peptide + Density is an AM/PM or alternate protocol - not “buy both for the same claim.” Recovery is overnight barrier and fibre repair, not a length story.
Named protocols (education, not checkout bundles yet): Length Protocol (Peptide + Recovery) · Density Protocol (Density + Foam) · Full Standard (all three).
Questions, answered
Can I use the Bioactive Density Lash Serum with lash extensions and lifts?
Yes. It is prostaglandin-free and applied once daily to a clean, dry upper lash line. Because the formula is water-based rather than oil-based, it is formulated without oils that can weaken extension adhesive; simply let it dry before applying anything else, and ask your technician to review the INCI if needed.
Does this serum contain prostaglandins?
No. The Bioactive Density Lash Serum is formulated entirely without prostaglandins or prostaglandin analogues. This matters because prostaglandin-based serums are the class most associated with eye-area side effects such as skin darkening and iris colour change, so a prostaglandin-free formula is a deliberate safety decision; it leans on a botanical bioactive and peptide complex instead.
What is the botanical bioactive complex, and how is it different from a pure peptide serum?
It is a hybrid formulation: a plant-derived complex of green tea, larch wood, red clover and rosemary extracts working alongside a signal peptide, Acetyl Tetrapeptide-3. A pure peptide serum relies on peptides alone, whereas this formula pairs peptide technology with botanical bioactives on a hyaluronic-acid base, which is why we classify it as a hybrid rather than a peptide or natural formulation.
Can I use it if I have sensitive eyes?
It is fragrance-free and formulated for the lash line, but as with any leave-on eye-area product we recommend a patch test first. In the interest of full disclosure, the formula contains sodium metabisulfite, a sulfite antioxidant that stabilises the botanical actives and is distinct from the sulfates this serum is free from; sulfites can be a sensitiser for a small number of people, so discontinue use if any irritation occurs.
How does it fit into a daily routine, and can I layer it with other products?
Apply once daily to a clean, dry upper lash line and let it dry before mascara, makeup or a daytime serum. It layers cleanly under other products. With Peptide Lash Serum, use as an AM/PM or alternate protocol, Density for the denser-looking line, Peptide for length/condition appearance, not both for the same claim.
Can I use Peptide Lash Serum and Bioactive Density together?
Yes, as a protocol. Peptide Lash is Peptide Technology (look of length and condition). Bioactive Density is Bioactive Follicle Support (denser-looking anchorage). Use one morning and one night, or alternate. They are not two versions of the same fullness claim.
What should I expect, and when?
Expect a conditioned lash line and, with consistent daily use, the look of a fuller, denser lash line; this is an appearance-based conditioning serum rather than a prostaglandin treatment, so it makes no physiological promise. Third-party testing for this finished formula is held on file under lab reference RL-BDS-003 and available on request, and results vary between individuals.