.png)
How to Clean LEGO Bricks Safely: LEGO's Official Method and the Mistakes That Ruin Them (UK Guide 2026)
- Sally Holmes
- 11 minutes ago
- 6 min read
The short answer: wash LEGO® bricks by hand in water no hotter than 40°C (104°F), using a soft cloth or sponge and a little mild detergent, rinse them in clean water, then leave them to air-dry indoors and out of direct sunlight. That is LEGO's own official guidance, and the reason behind it is simple — LEGO bricks are moulded from ABS plastic to extremely tight tolerances, and heat is the one thing that changes their shape permanently. A warped brick never clutches properly again, and there is no way to fix it. This guide covers the full method, what to do differently with minifigures, printed parts and electronic components, how long drying really takes, and whether the hydrogen peroxide trick for yellowed bricks is actually worth doing.
What does LEGO officially say about cleaning bricks?
LEGO's customer service guidance is short and specific. Clean pieces by hand using water no hotter than 104°F / 40°C with a soft cloth or sponge. You can add a mild detergent to the water, but rinse well with clear water afterwards. Higher temperatures, LEGO warns, may affect the quality of the bricks.
The list of things LEGO explicitly tells you not to do is just as useful: no washing machine, no dishwasher, and no drying in the oven, the microwave or with a hair dryer. It also says not to leave bricks in direct sunlight to dry. Every item on that list is a heat problem. When bricks get really hot they change shape, and a brick that has changed shape no longer works as a brick.
Can you put LEGO in the dishwasher or washing machine?
Officially, no — and the temperature maths explains why. A domestic dishwasher typically runs its main wash somewhere between roughly 50°C and 65°C depending on the programme, and a heated drying cycle goes hotter still. That is comfortably past LEGO's 40°C ceiling before you even get to the drying stage.
Washing machines add a second problem on top of heat: agitation. Bricks tumble against the drum and each other for the length of a cycle, which chips edges, dulls the surface finish and wears printing off minifigure parts. Small pieces also escape through the drum holes and end up in the filter or the pump.
Plenty of people do machine-wash bulk LEGO anyway, usually in a zipped mesh laundry bag on the coolest available cycle with heated drying switched off. It often comes out fine. It is still outside LEGO's guidance, and the failure mode is permanent — warping is not reversible. If the bricks matter to you, the sink is the safer tool.
The best way to wash a big tub of loose bricks
This is the scenario most people actually face: a tub of mixed bricks that has been under a bed for five years, or a bulk lot bought second-hand. A 1,000-piece LEGO Classic tub such as Lots of Bricks (11030) is a typical example — mostly plain, unprinted bricks, which is the easiest category to clean.
First, sort out everything that should not go in water: electronic parts, battery boxes, motors, light bricks, anything containing metal, stickered pieces, printed minifigure parts, and obviously paper instructions and cardboard. Deal with those separately.
Then fill a bowl or a sink with lukewarm water — hand-warm, not hot — and add a small squeeze of mild washing-up liquid. A zipped mesh laundry bag, the kind sold for washing delicates, is the single most useful tool here: it stops small parts disappearing down the plughole and lets you lift the whole lot out in one go.
Ten to fifteen minutes of soaking handles general dust and grime. For stubborn dirt in the corners of studs and tubes, work piece by piece with a soft-bristled toothbrush and light pressure. Rinse thoroughly in clean water afterwards — detergent left behind dries into a film and leaves bricks feeling faintly tacky. Finally, spread everything out in a single layer on a towel, indoors, away from radiators and sunny windows.
Minifigures, printed parts and stickers need different treatment
This is where most cleaning damage happens. The detail on a minifigure's face, torso and legs is printed onto the surface of the plastic — it is not moulded into it. Long soaks soften it and abrasive scrubbing takes it straight off. A minifigure from a collectible series like Series 27 (71048) is nine pieces, and almost all of its value is in that printing.
So: do not soak printed parts. Wipe them with a damp cloth, or dip and rinse quickly rather than leaving them sitting in water. Never use vinegar, bleach, methylated spirits, acetone or any abrasive cream cleaner on printed pieces — all of them strip printing, and some will haze the plastic permanently.
Stickered pieces are the same story with an extra failure mode: water creeps under the sticker edge and lifts it, and once a sticker has lifted it will never sit flat again. Wipe the surface of the tile, do not submerge it. Fabric capes, minifigure hair and rubber parts can be hand-washed, but squeeze rather than wring them and dry them flat.
How to clean electronic parts, motors and anything with metal
LEGO's advice here is separate and clear: for electronic components, or other sensitive bricks and pieces that contain metal, clean with a cloth moistened with water and a mild detergent that has no perfume or oil in it.
In practice that means Powered Up and CONTROL+ hubs, motors, battery boxes, light bricks and any piece with metal contacts get a damp cloth and nothing more — never a soak, never a rinse under the tap. Take batteries out first, both so you are not wiping around a live circuit and because a forgotten battery in a damp box is how you end up with corrosion and a ruined battery compartment. Anything with exposed metal, including older train track contacts, should be dried immediately rather than left to air-dry.
Why does old LEGO turn yellow, and does hydrogen peroxide really fix it?
Yellowing is not dirt, which is why washing never touches it. It is a chemical change in the surface layer of the ABS plastic itself, driven mainly by UV light, with heat and time making it worse. White, light grey and the old light-grey shades show it most obviously, which is why classic Space and Castle sets are the usual casualties.
The fix people talk about is retrobrighting: submerging the pieces in a hydrogen peroxide solution and exposing them to UV light for anywhere from a few hours to a few days. It genuinely works, and the before-and-after photos are dramatic. The honest caveat is that it reverses a surface reaction rather than repairing the plastic. Builders who have done it widely report the yellowing returning within months to a couple of years — sometimes worse than it was originally, and even on pieces stored in the dark. There are also reports of treated plastic becoming more brittle. It is not a LEGO-endorsed process, and you are using a chemical that needs gloves and eye protection.
For a display centrepiece that just needs to look right for a while, it may be worth it. If you want a permanent result, replacing the affected pieces — through LEGO's own Bricks and Pieces service or the second-hand market — is more durable. And prevention beats both: keep built sets off sunny windowsills and out of direct light, because that is where almost all of this damage comes from.
How long does LEGO take to dry — and how do you avoid mould?
Longer than people expect, because LEGO pieces are hollow. Water gets trapped inside the tubes of a 2x4 brick, inside minifigure heads and legs, inside Technic pins and inside every hollow stud. The outside feels dry within a couple of hours; genuinely dry all the way through takes roughly 24 to 72 hours depending on how warm and how airy the room is.
Speed it up the safe way: shake or tip each handful to empty the hollows, spread pieces in a single layer rather than a pile, turn them once partway through, and put a fan on a cool setting nearby or open a window. Do not reach for a hairdryer, a radiator, an airing cupboard or a sunny windowsill — those are exactly the heat sources LEGO warns against.
The mould question is really a drying question. Bagging or boxing bricks while water is still sitting inside them is what produces the musty smell people notice weeks later, and mould inside a hollow brick is very difficult to shift. If in doubt, give it another day on the towel.
None of this is difficult, but it is the unglamorous side of owning a lot of LEGO® — and it is part of why some families would rather rotate sets than keep accumulating them. That is the thinking behind LendABrick: sets arrive cleaned and checked, you build them for as long as you like, and when you are finished you send them back and something else turns up. Plans start at £9.49 a month, which undercuts the starting price of other UK LEGO rental services, with free Royal Mail Tracked 48 delivery and no minimum term — and an invitation-only VIP tier that nobody else offers. Either way, the 40°C rule still stands.
Comments