On slugging — the petroleum-jelly seal, in plain English.

Slugging looks unsexy and works beautifully. The technique is older than the trend — petroleum jelly has been the cheapest occlusive in pharmacology for a hundred and fifty years — but the recent attention dragged it out of the eczema aisle and into the routines of people whose skin simply never feels finished by morning.

It is not for every skin and not for every night. The protocol below is the one that works without the side effects most people warn about — the trapped sweat, the next-morning congestion, the pillowcase you have to throw out.

1. Cleanse, then wait.. Wash with whatever cleanser you usually use at night. Pat dry. Then wait two full minutes. Slugging on damp, freshly-cleansed skin traps water against the surface in a way that often reads as overnight congestion the next morning. The skin needs to settle to its baseline first.
2. Run your full nighttime routine.. Serums, treatments, eye cream, moisturiser — whatever your normal stack is. Pause thirty seconds between each layer to let it absorb. The petroleum jelly is the seal on top; it is not the moisturiser. If there is nothing underneath it, there is nothing for it to seal in.
3. Warm a pea-sized amount.. Pure petroleum jelly is solid in the tin. Take half a pea — really, half — and roll it between your fingertips for ten seconds until it goes liquid. Less than you think. The amount that fits comfortably on a fingerprint is enough for the entire face.
4. Press on a thin layer.. Press the warmed product across the cheeks, forehead, nose, and chin. Avoid the immediate eye area. Press, don't rub — rubbing disturbs the routine underneath. The film should be thin enough that the skin still looks like skin, not like glass. Glass is too much.

An occlusive doesn't add moisture. It stops the moisture you already applied from leaving overnight.