Why did my dishwasher make my cutlery rust?

LG dishwasher
(Image credit: LG)

After years of living in small flats with even smaller kitchens, I could wax poetic about the endless joys of having a dishwasher now that I finally live somewhere big enough to house one. I genuinely couldn’t imagine returning to a life where I had to shimmy into the washing-up gloves every evening, which is why I was so frustrated when I realized that my dishwasher was doing more harm than good to my cutlery.

For a few months, I’d noticed small reddish-brown marks on my plates and mugs after they’d finished going through a cycle in one of the best dishwashers. I was confused by this and couldn’t really figure out why this was happening. In true-to-form fashion, I mentally shrugged and decided not to really worry about it unless it got worse (spoiler alert – it did). 

This weekend, as I was putting away newly washed cutlery, I realized that there was a small nick in the facade of one of my forks, with rust forming around it. Immediately perturbed, I started to closely examine all of my cutlery and quickly realized that almost half of my knives, forks, and spoons were similarly afflicted. In a total coin-drop moment, I also realized that the red-brown spots on my crockery must have been caused by spots of rust being washed around the dishwasher during a cycle. 

While ingesting small amounts of rust ordinarily won’t affect your health, it’s obviously not a good idea to keep using rusty cutlery in the long term. I reluctantly threw out my old cutlery and bought an entirely new set. However, replacing my cutlery didn’t fix the root cause of the problem – why was my dishwasher making my cutlery rust in the first place?

I consulted David Palmer, LG’s Senior Product Specialist of Home Appliances, who said, “Metals can begin to rust when they come into contact with oxygen or water. This is a natural chemical reaction and does not mean your appliance is faulty. Salty and acidic water can further speed up the corrosion process, causing your cutlery to rust quickly.

Combining grease, moisture, and heat for prolonged periods of time inside your dishwasher can also cause corrosion on stainless steel. Leaving your dishwasher closed after a cycle will keep residual steam in the appliance, which will cool and condense on items, leaving them damp for longer periods."

3 ways I stopped cutlery rusting in my dishwasher

1. I used a hotter wash cycle

As we all know, metal + water = rust, so I quickly realized that the core problem I was facing was that my cutlery was being exposed to water for too long through my dishwasher, not drying properly. In an effort to be more environmentally friendly, I’ve always used my dishwasher’s Eco setting, which washes at roughly 144ºF. However, one of the ways that a dishwasher dries effectively is through getting really hot so that the water evaporates.

I realized that using the lower temperature Eco setting might have prevented my dishes from drying effectively. Instead, I switched to the 160ºF Intensive setting, and I instantly noticed a difference. When I previously opened my dishwasher after a cycle, most of my dishes would still be wet – especially on the top shelf where the bowls and mugs usually reside. However, the Intensive setting means that most of my dishes are pretty much bone-dry at the end of the cycle. 

However, it's worth noting the Eco setting is necessarily something to avoid. David Palmer says, "If washing a full load, the eco cycle is always the most effective, though it may take slightly longer. The slower heating of water and longer cycle means the wash has same effectiveness with less water and energy." The issue with my own dishwasher's Eco setting was the comparatively lower temperature of the water, not the length of time it was washing for. 

2. I changed the time of day I’d use the dishwasher

My regular dishwasher routine was that I’d slowly load it up throughout the day and then put it on just before bed. This meant that I would wake up to squeaky-clean dishes, and I wouldn’t have to listen to the sloshing of the wash cycle either – win. However, in an effort to ensure that my dishes and cutlery weren’t sitting in water for too long, I decided to change my routine so that I turned on my dishwasher in the morning instead. 

This means that I can put away my dishes and cutlery as soon as the cycle is finished rather than letting them sit in the water all night. I initially thought that this new routine was going to be an annoying inconvenience, but it’s actually been a surprisingly seamless transition.

3. I manually opened the dishwasher door after its cycle

While I’ve been endeavoring to put away my dishes as soon as the dishwasher has finished, sometimes I’m in the middle of a task (or I’m just being lazy!). However, one of the ways to help prevent water from collecting on your dishes is to slightly open the dishwasher door once its cycle is finished. This will help to circulate air around the dishwasher, preventing condensed water from settling back on your dishes. 

However, it’s important to note that you shouldn’t open your dishwasher door too early, as the drying process won’t be over yet. This means that you could actually make more water settle on your dishes! I usually wait until the dishwasher cycle has fully ended before I open the door. 

David Palmer adds, "Moisture is the number one cause of rust. As mentioned above, the air inside your dishwasher is humid after a wash; therefore, it is beneficial for users to open the door a couple of minutes after the cycle ends to let the humid air escape, or if you can’t unload straight away, take out the wet cutlery to assist with the drying."

It should be noted that some dishwashers actually have features that will automatically open the door when the cycle ends so that you don't have to do it manually, but my own isn’t as fancy as that! However, David Palmer says that LG's Auto Open Dry feature "allows steam to escape the dishwasher cavity, therefore, enhancing drying performance. At the end of the cycle the products with this feature will open the door by 8°, it will only do this once the internal tub temperature is 50°C to avoid any scolding."

5 other dishwasher drying tips

While the tactics I used worked well for me, there's still more you can do to ensure that your dishes are perfectly dry by the time you unload your dishwasher. David Palmer from LG has provided five top tips to help you get the best possible results at the end of every cycle. 

David Palmer LG
David Palmer

David Palmer is the Senior Product Specialist of Home Appliances at LG Electronics, giving a unique insight into how we can all make the most out of our home appliances. 

1. Avoid washing non-dishwasher-safe or corroded kitchenware

Not all metals are dishwasher safe. In addition, low-quality metal or metal-coated items are prone to rusting if washed in the dishwasher.

LG’s large capacity and EasyRack™ plus feature means you can adjust the height levels and flexible tines in the rack to accommodate all types of kitchenware. However, although items such as knives tend to be made of harder steel that gives them a lasting edge, these are also more likely to rust eventually from repeated washing in a dishwasher, so it’s best to hand wash these items.

LG recommends avoiding putting sharp knives in your machine, especially if you have invested in some expensive ones. Dishwasher detergent is abrasive, so it can dull the knife; it can also hit other items, further damaging the blade. Ceramic knives should also not go in dishwashers as they are more brittle.

Rust can spread between metal utensils. So, to protect your other metalware, don’t put rusty items in the dishwasher.

2. Consider your stacking style

Make sure your dishes are loaded properly and that they’re not touching each other. Overpacking the cutlery basket can result in staining. The top rack on the LG QuadWash™ Dishwasher comes with a cutlery tray, so items won’t touch each other. It's important that stainless steel and silver-plated or copper items don't come into contact, as the chemical reaction with hot water and dishwashing detergent can cause discoloration.

For many dishwashers, the sprayer arm works from the middle out, so you want your load to face the middle of the machine to ensure it gets the proper spray treatment required. However, with four-arm appliances (instead of two) now available with LG’s latest QuadWash™ Dishwasher, you have flexibility in your loading as multi-directional rotation cleans from every angle. Just make sure not to obstruct the arms!

3. Avoid using inappropriate detergent or spilling salt

The most common mistake we tend to make is using far too much detergent. Not only does this cost us money, but it can scratch dishes or result in cloudy glasses or visible spots – a common pain many tend to encounter.

A simple hack for this involves placing a bowl full of vinegar on the top rack before a cycle, which acts as a rinse aid and combats water staining. However, in LG’s new range, the QuadWash™ feature will ensure an effective wash as TrueSteam™ technology emits high-temperature steam to clean thoroughly and reduce undesirable water spots, eliminating these problems from arising and giving your glasses an extra shine.

Be sure to use detergents, rinse aid, and salt, which are specifically for dishwashers. Dishwasher salt has a corrosive effect on metal surfaces, and salt inside the dishwasher tub may scratch glassware.

Users can even run a prewash program or the shortest program to wash away any salt that may have been spilled inside the appliance. With LG’s range, the salt reservoir screws on, and the rinse aid clicks shut to prevent spilling. Just be careful not to pour any dishwasher detergent directly onto cutlery.

4. Scrape off salty solids

Although scraping off bits of food is important, particularly any salty solids, we usually recommend that you don’t need to rinse your dishes before you put them in the dishwasher, as this often makes the soap less effective. However, if you’re not running your appliance for a while, cutlery may be an exception to this rule.

But for those plates that do need an extra powerful spray, LG’s Dual Wash features enable you to wash at different intensities on the top and bottom racks.

5. Clean your dishwasher

You’d think dishwashers would be inherently clean, but over time, they often collect food debris, soap residue, and gunk that needs to be wiped away.

Inside your appliance, dishes are sprayed and sterilized with hot steam to eliminate 99.999% of bacteria and viruses. However, it's important to clean your appliance, and LG recommends doing a tub cleaning every 30 cycles to ensure your dishwasher can perform to the best of its ability.

Louise Carey

Louise is the former Editor of Top Ten Reviews. With six years of editorial experience across print and digital brands, Louise has written for a variety of publications, including TechRadar and The Independent. When she's not checking comma placements and finding the best brands for Top Ten Reviews readers, you can either find Louise exploring the countryside with her camera or teaching her border collie fun new tricks.