The Science of Occlusion

Petrolatum is an amorphous mixture of hydrocarbons derived from petroleum that forms a semi-permeable film on the skin surface. Unlike oils (which are absorbed), petrolatum sits on the surface and physically reduces TEWL by up to 98% — making it the most effective occlusive agent available, outperforming plant oils, silicones, and waxes at the same thickness. It does not penetrate the skin or affect sebum production. It is inert, hypoallergenic, fragrance-free, and non-comedogenic when applied over a clean, properly prepped skin — contradicting the popular belief that it causes breakouts. (Sethi A et al. PMID: 19588637)

During sleep, skin enters a repair phase with elevated cell turnover and growth factor activity. TEWL naturally increases during sleep compared to waking hours. Slugging counteracts this nocturnal TEWL increase and creates an optimal hydration environment for barrier repair and active absorption.

Who Should Slug (and Who Should Not)

Ideal for slugging: Dry skin types with chronically compromised barriers. Dehydrated skin needing intensive overnight repair. Post-procedure skin (after microneedling, chemical peels, laser — occlusion dramatically accelerates wound healing). Winter or low-humidity environments causing barrier stress. Anyone experiencing barrier disruption from retinoid use.

Should NOT slug: Acne-prone and oily skin — while petrolatum itself is non-comedogenic, the occlusion traps sebum and existing bacteria against the skin surface, worsening breakouts. Fungal acne (Malassezia) prone skin — occlusion creates the warm, humid environment Malassezia thrives in. Skin with active infected breakouts or open wounds (outside of medical wound care context).

How to Slug Correctly

The order matters critically. Petrolatum is an occlusive — it seals whatever is beneath it. Apply it last, over a completed skincare routine. Never apply petrolatum directly to bare skin and call it slugging — you are sealing in nothing useful. Never apply petrolatum over actives that need to be rinsed (AHAs, BHAs, benzoyl peroxide) — the occlusion will dramatically increase penetration and cause severe irritation.
Safe actives to slug over: Hyaluronic acid, glycerin, niacinamide, ceramide moisturiser, squalane, peptide serums. These all benefit from enhanced absorption under occlusion.
Never slug over: High-concentration retinoids (risk of retinoid dermatitis), AHAs or BHAs (risk of chemical burn), benzoyl peroxide (risk of severe irritation).

The SS Slugging Protocol

Standard Overnight Slugging (dry and dehydrated skin):
1. Gentle cream cleanser — pat dry, leave slightly damp
2. Hyaluron 3D Hydrator Multi Lamellar Cream-Serum — apply to damp skin
3. Peptide Serum — allow to absorb 60 seconds
4. Black Rice Niacinamide Concentrate — allow to absorb
5. Ceramide-rich moisturiser
6. Thin layer of petrolatum (Vaseline) over everything — press gently, do not rub

Retinol Slugging (barrier protection method for retinoid users):
1. Gentle cleanser
2. HA serum on damp skin
3. Retinol 0.3-0.5% — allow 20-30 minutes to absorb (important — do not rush)
4. Ceramide moisturiser
5. Thin layer of petrolatum as final seal
This is the ‘retinol sandwich plus occlusion’ method — it reduces retinoid irritation while maintaining efficacy. Particularly useful for retinoid beginners and dry or sensitive skin.

Frequency: 3-7 nights/week depending on skin dryness. Reduce frequency if skin feels congested or breathless. Increase in winter or during periods of barrier stress.

Results Timeline

Night 1: Skin visibly plumper and more hydrated on waking.
Week 1-2: TEWL measurably reduced, barrier function improving.
Month 1: Significant improvement in dry patches, tightness, and barrier resilience.
Ongoing: Maintained with consistent nightly or regular slugging routine.

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