The dishwasher is undoubtedly an essential household that makes your life easier. It can be the ultimate time-saver when it comes to cleaning up grubby pots and pans or dirty dishes. But it's not a cure-all. There are some items that should always be washed by hand as the high temperature of the appliance could ruin their surface. Here are the 10 items that you should never put in the dishwasher.

Knives – If you want your kitchen knives to stay sharp, you should never put them in the dishwasher. Dishwashers can dull knives blades, so wash knives by hand.

Crystal glasses – The high water temperature may leave your crystal chipped, or dull the gorgeous finish of crystal items. So always wash your crystal glasses by hand.

Wooden items and utensils – Very hot water can damage the finish on wooden items and utensils. Hand wash only and don't soak for a long time.

Copper pots, pans and items –  These items should be washed by hand and, perhaps, polished with lemon. Avoid popping copper pots in the dishwasher as aggressive detergents and the high water temperature can dull copper's shine and finish.

Cast iron – Water can leave cast iron utensils vulnerable to rust. Cast iron items should be washed by hand to avoid damage.

Nonstick pans –Teflon-type cookware is a nonstick coating that could expose you to toxic chemicals that might cause cancer. So do not put nonstick cookware in the dishwasher. The dishwashing process and high temperature can break down the coating, causing it to flake off.

Stoneware – Stone is usually very porous so very hot water can damage it.

Hand-painted ceramics and porcelain – Usually ceramic and porcelain can be put in the dishwasher, but hand-painted dishes or cups may be ruined.

Aluminum cookware – Aluminum is a very light material that can be damaged in the dishwasher because of contact with pointed objects and hot water.

Jam jars – Jam jars are durable and can be used in a variety of ways but you should avoid washing them in a dishwasher as the labels can clog and damage the dishwasher.