If a plate, bowl, serving spoon, glass, or other item has sentimental or monetary value and you are unsure how it was made, wash it by hand.
Older pieces may contain delicate glazes, adhesives, hand-painted decoration, or materials that were never tested for modern dishwasher conditions.
Why Dishwashers Can Be Harsh
A dishwasher does much more than spray warm water. During a typical cycle, dishes may be exposed to:
- Strong alkaline detergent
- Pressurized water jets
- Hot wash and rinse water
- Extended moisture exposure
- Heated drying
This combination is effective for durable ceramic plates, stainless-steel cutlery, and dishwasher-safe glassware. Delicate materials, natural finishes, adhesives, and some metals may respond poorly.
The Role of Dishwasher Detergent
Dishwasher detergent is formulated to break down food, grease, and stains without manual scrubbing. Because it must work automatically, it is generally more alkaline than ordinary hand-washing liquid.
This is one reason certain metals, nonstick coatings, wood finishes, and decorative surfaces may deteriorate after repeated cycles.
Do not use ordinary hand-washing liquid in an automatic dishwasher. It can create excessive foam, overflow from the appliance, and interfere with proper cleaning.
Heat Can Be as Damaging as Detergent
Some items tolerate water but cannot withstand repeated exposure to high temperatures. Dishwasher heat may cause:
- Warping
- Cracking
- Adhesive failure
- Fading
- Peeling
- Coating deterioration
- Drying and splitting of natural materials
The heated-dry setting may be especially demanding for plastics, insulated containers, wood, and objects assembled with adhesives.
How to Know Whether an Item Is Dishwasher-Safe
Look for a care label on the bottom of the item, its original packaging, or the manufacturer’s website. A dishwasher-safe symbol often resembles plates or glasses beneath water droplets, although symbols vary between manufacturers.
Do not assume that an item is dishwasher-safe simply because it is made from glass, metal, silicone, or plastic. Construction, coatings, decoration, and adhesives can change how the product should be cleaned.
If the label is unclear and the item is valuable or difficult to replace, hand washing is the cautious choice.
What Does “Top Rack Only” Mean?
Some plastic products carry a “top rack only” instruction. This usually means they should be kept farther away from the dishwasher’s strongest heat source.
Ignoring this instruction can lead to warping, shrinking, or deformation. Place lightweight objects securely so water pressure cannot turn them over or send them into the bottom of the appliance.
Why Proper Loading Matters
Even dishwasher-safe items can become damaged when loaded incorrectly. Avoid:
- Allowing glasses to touch one another
- Placing sharp objects where they can strike delicate dishes
- Blocking the spray arms
- Nesting bowls so water cannot reach their interiors
- Overcrowding the racks
- Positioning tall items where they obstruct detergent dispensers
- Allowing lightweight objects to fall onto a heating element
Correct loading also improves cleaning because water and detergent can reach each surface more effectively.
Should Knives Point Up or Down?
For ordinary table knives, follow the dishwasher manufacturer’s loading instructions. Place utensils in a way that minimizes injury during loading and unloading.
Sharp chef’s knives are better washed by hand because dishwasher detergent, heat, moisture, and contact with other utensils can dull the edge or damage the handle.
If a sharp utensil must be placed in the dishwasher and its manufacturer permits it, position it so that it does not create a cutting hazard when the basket is unloaded.
