Why does my stainless steel flatware get horrible pitting, staining and rusting deposits in the dishwasher ?
'Stainless steel' is steel to which chrome has been added for rust resistance and often nickel for acid resistance. Top-quality stainless steel (18/10) contains 18% chrome and 10% nickel. It's generally more expensive - and brighter and whiter in colour - than lower-grade 13/0 stainless steel, which can look quite grey. And despite its name, most metal alloys used in cutlery make it stain-resistant rather than stainless.
While most forks and spoons have excellent corrosion resistance, knife blades tend to be made of harder steel that gives a lasting edge but is more likely to rust, eventually, from repeated washing in a dishwasher. If you examine your flatware, you'll probably notice that those that have rust are generally the knife blades.
The hints below can help you minimise this risk.
Tips to reduce rust
- Acidic and salty food remnants on cutlery will stain it. Rinsing the pieces off before you put them in the dishwasher, especially if you don't run it immediately, will help avoid this.
- Storing dirty cutlery in your dishwasher for days will stain it eventually.
- Washed and wet cutlery in the dishwasher overnight will add to the chance of staining. Opening the door when the cycles finished will assist drying, or take it out and wipe it dry straight after the program finishes.
- Over-packing the cutlery basket means staining. Use a grid (technically known as an anti-nesting grid), so items don'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 discolouration.
- Don't pour dishwasher detergent directly onto cutlery. Harsh dishwasher detergents can over time, cause staining. Silver-plated cutlery becomes permanently stained and stainless steel can pit within minutes.
- Don't soak cutlery for long periods in soapy water, bleach solutions, or salt water.
- Don't use abrasive cleaning aids.
- Stains such as water marks can generally be wiped off easily from knife blades, and for more persistent rust stains, use a non-abrasive metal cleaning paste or liquid - one formulated for stainless steel, not a silver cleaner - if necessary.
- For rainbow-like stains, use lemon juice.
Experts generally recommend washing high-grade knives by hand! Apart from risking rust stains, their sharp edges can deteriorate in the dishwasher as they get bumped into other dishes, cutlery or against the rack, all of which can blunt the blades. And, of course, it's safer not to have sharp knives hidden in among all the rest of the cutlery.
Removing rust spots
Maybe you've got scratches in your cutlery and the strong bleaching agents from dishwasher detergent have stripped some of the chrome from your stainless steel. Rust stains have developed and you're worried that they'll spoil the look, or you might have safety concerns. A plastic scourer with a baking soda paste (a little water and soda) rubbed over the rust spot and then further rubbed by a paper towel should remove the rust spot.
Key things to remember when removing the rust spot - don't use a metal scourer, it'll strip more of the chrome (Cause scratches). The same goes for abrasive powders, they'll also strip the chrome out of your cutlery. Stick with some gentle rubbing. Other suggestions are lemon juice to loosen the rust from the cutlery.