A translucent TPU bag cleans up in about two minutes with a damp cloth. The whole skill is knowing the three things that damage it permanently — and none of them is dirt.
What follows is written for bags made of frosted TPU, the material of our Jelly Firkin. If your bag's product page never states its material, assume it is PVC and treat it more gently than this: less rubbing, cooler water, no soap left sitting on the surface.
Routine care: a damp cloth, nothing more
In the great majority of cases nothing else is needed. Take a soft cloth — microfibre is ideal, a well-worn cotton one works — dampen it with lukewarm water, wring it out until it is barely wet, and go over the whole surface. Dust, fingerprints, sand and city grime come away without pressure.
Do the inside at the same time. Empty the bag, turn it upside down outdoors to shake out sand and crumbs, then wipe the interior with the same cloth and reach into the corners with a fingertip behind the cloth.
Then let it dry in open air, away from any direct source of heat. No hairdryer, no radiator, no long spell in full sun. Prop it open so the two faces are not resting against each other, and dry the closure and the handle fittings with the cloth rather than leaving water standing on them.
A useful rhythm: a quick wipe when you put the bag away for the week, and one proper clean at the end of a beach or festival stretch, when sunscreen and salt have had time to build up.
Stubborn marks
For a greasy mark, a smear of sunscreen or hand cream, or colour transferred from dark denim, add a single drop of mild soap to the damp cloth — a neutral liquid soap, or a plain unperfumed household soap. Work in light circles. Do not scrub: pressure does nothing that patience will not do better.
Then rinse the cloth in clean water and go over the same area again to lift every trace of soap. Soap residue left on the surface dulls the transparency and leaves a faint film that catches dust. The rinsing pass is not optional.
Two marks deserve a specific word. Sunscreen is the most common cause of stubborn patches on clear bags: wipe it off the day it lands rather than at the end of the trip. Dye transfer from dark denim behaves the same way — it comes off readily in the first days and progressively less well after that. Speed matters more than any product.
Whatever you use, test it first on the base of the bag, where nobody looks.
| What you are dealing with | What to do |
|---|---|
| Dust, fingerprints, sand | Damp cloth, then air dry |
| Grease, sunscreen, hand cream | Damp cloth with one drop of mild soap, then a clean-water pass |
| Dye transfer from dark denim | Same method, acted on early; the longer it sits, the less lifts |
| Surface feels tacky | Usually product residue — soap, then rinse. If it appeared after heat, it is the material and not the surface |
| Cloudy or milky patches | Solvent damage. Not reversible |
| Crumbs and sand inside | Empty, turn out, wipe, and dry fully before closing the bag |
The three mistakes that cannot be undone
1. Acetone, alcohol and solvents
Nail polish remover, rubbing alcohol, hand sanitiser, white spirit, paint thinner and disinfectant wipes all attack TPU. The damage is immediate and permanent: the surface hazes over, turns milky, and never becomes clear again. Bleach belongs on the same list, and so do melamine "magic" sponges and scouring pads, which take the polish off the material by abrasion rather than by chemistry.
If a cleaning product describes itself as a degreaser, a solvent or a disinfectant, it is not for this bag. Water and a drop of mild soap will handle everything a bag actually encounters.
2. The washing machine
Not the washing machine, and not the dishwasher. Heat and mechanical agitation together deform the body of the bag, and neither the closure nor the handles recover their shape. There is no gentle cycle that makes this safe.
3. Heat, in every form
A bag left in a parked car in summer, resting on a radiator, or dried with a hairdryer will lose its shape. TPU is a thermoplastic: it softens as it warms, and it keeps whatever shape it was holding when it cooled. This is also the most frequent cause of a surface that has gone permanently tacky, and a closed car in summer is the most dangerous place you can leave the bag.
How to store it
Store it filled rather than folded. A little tissue paper or a rolled scarf inside is enough to keep the shape, and it also keeps the two faces apart. Stand it upright rather than laying it flat.
Do not crush it under other bags on a shelf. A crease held for months eventually becomes permanent, and a crease in a translucent material is far more visible than a crease in leather.
Keep it out of direct light, at room temperature, and away from anything that transfers colour — newspaper, dark dyed fabric, a printed dust bag. Make sure it is completely dry before you close it and put it away.
Does TPU yellow?
This is the question we are asked most often, and it comes from a confusion with PVC.
The jelly bags of the 2000s were made of PVC. They yellowed, hardened and cracked after a couple of seasons, and that memory is what people are really asking about. TPU is a different material: softer to the hand, more resistant to cold and to abrasion, and it does not yellow the way PVC does.
Which is why the material stated on a product page matters as much as the colour. When it is not stated, it is rarely TPU. Our Jelly Firkin is made of frosted TPU, and we say so on the page.
And the charms?
Take them off before any wet cleaning. A charm in leather is not cleaned like TPU: wipe it dry, and keep soap and water away from it entirely. Cords and fabric elements come off for the same reason — anything that holds water will hold it against the bag while it dries.
Put them back only once the bag is completely dry, not while it is still faintly damp.
In short
Soft damp cloth, a drop of neutral soap if a mark needs it, a clean-water pass, and air drying. Never a solvent, never a machine, never heat. Store it filled, upright and out of the light.
Done that way, a TPU bag goes through season after season without changing. It is the cheapest maintenance routine any bag you own will ask of you.
Our Jelly Firkin is €53.90 in twelve colours, and the full range starts at €45. Shipping is free and the displayed price is the price paid, taxes included; orders leave within 24 working hours and arrive in four to nine working days depending on the country, with tracking.
Published 28 August 2026 by La Firkin, a Swiss maison — Lausanne.