Lids
The use of glass lids, plastic lids or plastic film is advisable because:
1.They prevent the release of excessive vapours especially when cooking for longer periods.
2.They increase the speed of heating food.
3.They prevent the food from drying up.
4.They prevent the loss of the food aroma.
The lids should have holes to avoid pressure. Plastic film should be perforated.
Baby bottles, baby food jars and other similar recipients should be warmed up without lids as they can burst.