The bird does the work; you provide the bathroom
Dust bathing is built into a chicken. Given dry, loose earth, a hen digs a shallow scrape, lies in it, and uses her wings and feet to throw dust up and work it through her feathers and down to the skin, then stands and shakes the whole lot out in a cloud. That working dust through the plumage is the point: fine dry particles reach the lice and mites that live on the bird, clogging and irritating them and making the feathers a far less comfortable home, and the shake afterwards throws dislodged parasites out with the dust. Your job is entirely about providing the right patch of ground and keeping it in the condition hens want to use.
Build the bath where it stays dry
Choose a spot under cover: beneath the raised coop, in the corner of a covered run, or under a simple roof of its own. A dust bath that fills with water or turns to mud in every shower will be abandoned, and wet earth does the birds no good at all. Fill a shallow border — old sleepers, a tyre or a low wooden frame keeps the material in — with a mixture of dry soil and sand dug or bought in, a hand's depth at least so a hen can really excavate. Many keepers stir in wood ash from a clean fire, which makes the mixture finer and drier still. What matters most is texture: loose, dry and dusty, like the patch hens choose for themselves under a hedge in a dry summer.
Watch them use it, and learn the flock from it
A well-made bath in a contented flock is a social venue: several hens will bathe together, usually in the warmth of the day, and the squabbling over the best spot is normal. Dust bathing is also quietly diagnostic. A hen who never bathes, or who is pushed out of the bath by the others, may be low in the order, unwell or already carrying the heaviest parasite load, and she is the one to catch and check first on handling day. Fresh dust thrown into feathers during the bath is also why handling checks often find fewer lice on keen bathers; the birds are doing a share of your parasite control for you, every day, for free.
Keep the bath working
Rake the bath over regularly to break up compacted patches and remove droppings, top it up as the level falls, and refresh the whole fill if it becomes stale or contaminated. In a fixed run, move or rest the bathing area if the ground around it gets sour. Check after heavy rain that the cover is doing its job; a bath that stays dry through a wet week is a bath the hens keep using, and continuity is what makes it useful against parasites rather than an occasional treat. In freezing weather the material may need loosening with a fork so the birds can still dig into it.
Know the limits of the method
In general terms, dust bathing is prevention and housekeeping, not a rescue treatment. A hen already crawling with lice, or a coop harbouring red mite in its cracks, will not be put right by a dust bath alone, because the bath only reaches the parasites on the bird during the day and does nothing about the ones living in the housing. Treat the bath as the flock's daily defence alongside clean bedding and regular handling checks, and step up to coop cleaning and proper advice when numbers climb despite it. Listing a weekly rake-over and top-up of the dust bath among your KinsLe Care Teams tasks means the area never quietly degrades into a muddy corner the hens have given up on.