How to clean building bricks: dishwasher, mesh bag, drying

Second-hand bricks, the box from the attic, toys after a cold – sooner or later building bricks need to go into the water. The plastic copes with water and dish soap without any trouble. What it does not cope with: heat, harsh cleaners and solvents. At the temperatures of a normal dishwasher cycle a brick can warp, and a 2×4 brick that is only slightly bent no longer grips. The good news: the safe method is also the easiest one.

Three methods compared

Hand washing is the standard. The machine barely saves time, because drying takes just as long either way.

Hand washing in six steps

1. Sort out. Parts with electronics or metal, printed and stickered parts and loose stickers stay out of the water. Wash transparent parts separately so they do not rub against studs and go cloudy.
2. Prepare the water. Lukewarm, no more than about 40 °C (105 °F) – it should feel pleasantly warm, not hot. Add a squirt of mild dish soap (washing-up liquid), roughly a teaspoon to two litres (half a gallon). No scouring cream, no bleach, no methylated spirits, no acetone.
3. Soak. 10 to 15 minutes, swishing now and then. For years of dust or sticky residue, up to an hour.
4. Brush. A soft brush or an old toothbrush gets dirt out of studs, tubes and seams. Cotton buds work for 1×1 parts and round bricks.
5. Rinse. Put the bricks in a sieve or a mesh laundry bag and swirl them under lukewarm water until no more foam appears. Soap residue dries into a film.
6. Dry. The longest step – more on that below.

A rough rule for quantities: a five-litre bowl takes about 300 parts at a time. More than that rubs together, and the bricks at the bottom never get clean.

Dishwasher and washing machine – yes, but only like this

The machine is tempting when you have 5,000 parts. It works if you stick to five conditions:

• Always in a mesh bag. A laundry bag with a zip, no more than half full. Loose parts jam the spray arm or the drum.
• No more than 40 °C (105 °F). Many dishwashers have a glass or delicate cycle at 35 to 40 °C; some only offer a cold pre-rinse. Normal and intensive cycles run hotter and are off limits.
• Heated drying off. The heating phase at the end of the cycle is the real cause of damage. If your machine has no cycle without heated drying, leave the dishwasher out of it.
• Top rack, little detergent. A small amount of powder instead of a tab; rinse aid leaves a dull film on plastic.
• Washing machine only on a delicate cycle at 30 °C (85 °F), the bag wrapped in a towel, spin off or on the lowest setting. The bricks rattle audibly – that is normal and the drum is not harmed. A tumble dryer is out of the question in every case.

Tiles, transparent parts and printed parts never go into a machine. They scratch, even in a bag.

Drying properly

Water collects in the tubes underneath and in the studs. This is how everything gets dry:

1. Shake the bag or sieve vigorously. A salad spinner with a few turns gets most of the water out.
2. Spread the bricks on a towel – in a single layer, open side down, so the tubes can drain.
3. Leave them for 24 to 48 hours at room temperature. Turn them over once after about twelve hours.
4. Not on a radiator, not in the sun, no hair dryer. Heat warps, sunlight yellows plastic.

The press test tells you whether everything is dry: press the underside of a 2×4 brick onto a paper towel. If the paper stays dry, the bricks can go back in the box. Damp bricks in a closed container smell musty after a few weeks.

Disinfecting, yellowing, smells

Disinfecting makes sense after a cold or for bricks from a nursery, but it is no reason for harsh chemicals. Dish soap and water remove most of the dirt mechanically. If you want more, use a mild product approved for children's toys and follow the dosage and contact time on the packaging. Rinse thoroughly afterwards. Bleach in high concentration and high-proof alcohol attack the plastic: it turns cloudy, goes brittle or cracks.

Yellowing is not dirt. White and light grey parts turn yellowish through sunlight and age, and that cannot be washed off. Prevention helps: store bricks in the dark, not by the window. Guides for brightening with hydrogen peroxide circulate online. It is laborious, does not last and does not belong in children's hands – we do not recommend it.

Smells of smoke or cellar sit deep in the material. What helps: two or three washes with longer soaking, a tablespoon of baking soda per litre of water, and then several days in the open air before the bricks go back into a box.

The checklist

Clean bricks, new plan

Freshly washed bricks are the best moment to reorganise your storage – the guide How to sort building bricks shows how. And while the bricks dry on the towel, you can already plan the next model: open the editor and build it in the browser first.