120-Litre Wheeled Bins vs 20-Litre Caddies: Two Dosing Schedules for One Kitchen

A 220-room hotel runs three kitchens. Back of house, six 120-litre wheeled bins leave the dock each night. Front of house, forty 20-litre caddies sit in pantry cupboards and service stations, emptied by the floor team at the end of each shift. The hotel buys one grade of polymer in 25-kilo bags and one laminated dose card. Within a month the caddies were setting like concrete and the wheeled bins were still slopping onto the yard. Same powder, same waste stream, different physics.

Bin geometry changes the dose more than most buyers expect, and the mistake is almost always in the same direction: a dose worked out on a small caddy gets applied unchanged to a bin four times deeper. This article sets out why depth matters, what each bin type needs in grams, and how to run two schedules out of one store cupboard without confusing the staff who cover both.

Depth, Not Volume, Sets the Working Dose

In a 20-litre caddy the waste sits 20 to 25 centimetres deep. Powder broadcast on the surface meets liquid within a few centimetres and the whole body of waste is reachable with a stir from a spoon. In a 120-litre wheeled bin the waste can be 60 centimetres deep, and powder dropped from the rim lands in a cone directly beneath the scoop. The outer ring of liquid never sees a granule. That is why a bin dosed at the caddy rate of 8 grams per litre can show a firm plug in the middle and free liquid at the edges, a pattern that looks like a product fault and is really a mixing fault.

The correction is twofold: raise the dose to 13 to 15 grams per litre for a wheeled bin, and dose in two passes. Half the powder goes in when the bin is about half full, the other half at 80 percent, each followed by 30 seconds with a long-handled paddle or a drill mixer on the lowest setting. Two passes cost nothing and remove most of the cone effect.

The Caddy Is a Portioning Problem, Not a Chemistry Problem

Nobody is going to weigh 160 grams of powder in a pantry at 23:00 with a queue of staff waiting to clock off. Caddies need pre-portioned doses: 40-gram sachets for a 20-litre caddy at typical fill, or a 50 ml scoop with a level line scored into it. Compliance is the whole game here. In a trial across 40 caddies, weighed doses were missed on 9 percent of shifts, while sachets were missed on 2 percent, and the difference was worth more than the sachet premium of about four cents each.

Front-of-house caddies also collect waste that is colder, wetter and more dilute than back-of-house waste: half-finished drinks, sauce, salad, ice. That pushes the dose up, not down. A caddy holding 8 litres of plate scrap and 2 litres of drink needs the dose for 10 litres, not for 8.

Two Cards, Two Colours, One Store Cupboard

The workable system is boring and visual. Blue scoop and blue card for caddies: one sachet or one level scoop per caddy, stirred, lid clipped. Red scoop and red card for wheeled bins: half the dose at half full, half at 80 percent, paddle after each. Put the par levels on the store room wall: forty caddies a day needs 1.6 kilos of sachets, six wheeled bins needs 7 to 8 kilos of bulk powder, and a hotel with both needs both lines stocked. Reorder at two weeks of cover, not two days.

When the Same Person Covers Both Routes

In smaller hotels the night porter does the caddies and the bins, usually in that order, usually in a hurry. Sequence matters: caddies first while the powder is dry and the hands are clean, wheeled bins second with the paddle, and the scoop wiped and returned to the tub rather than left on the dock where it absorbs humidity overnight. A scoop left out in a wet yard can pick up enough moisture in a week to halve its capacity, and the resulting soft sets get blamed on the last delivery.

Whether you are standardising forty caddies or six wheeled bins, the dose should follow the bin, not the habit. Send us your bin depths, fill volumes and collection times and we will map a two-tier dose schedule for your site; absorbency grades and pack formats are on the SAP powder products page.