Just recently, we have seen a number of microwaves come into the shop with problems caused by condensation so I thought I would post some information.
A certain a mount of heat is generated by the components in making microwave ovens. By design, a microwave oven draws in cool air (normally into the vent at the rear), it blows that air over the components to cool them and then blows that same air through the oven cavity to carry away heat (and smells) and condensation produced by the food heating up inside. This has a couple of effects. One is that if the oven successfully carries the condensation away and out of the oven ( The door doesn’t need to be airtight to stop microwaves escaping – but that’s another post !), that condensation needs to go somewhere and like our Panasonic at home we often end up with a small puddle on the worktop in front of the oven after we have cooked something containing lots of moisture (rice or jacket potatoes for instance). This isn’t a problem now you know but customers are often alarmed, thinking that if moisture escapes then the microwaves also are escaping. The second effect is that if this happens often, then the interior of the oven will eventually become damaged, if the interior of the oven is painted white the paint may lift and eventually rust. Nether of these are dangerous but in the long term will look unsightly and ultimately shorten the life of the oven.
To overcome this problem, the easiest solution is to avoid the build up of condensation. Does the food that you are cooking really need to be cooked on that power level for that long ? Cleaning the oven afterwards will definitely help. Just a wipe around with a cloth after using the oven will take away the worst and if you leave the oven door open just while you serve up will give it long enough to dry out in most cases.
If, like this picture the damage has already been done. It wont be dangerous at this point but wont look very nice. This might be a good time to touch up the paintwork to restore the white finish. In this case it may not be a very long term solution as the roller ring will inevitably antagonize the paint but it will prolong the life for sure. We sell a touch up paint kit which contains everything you need to repair a white cavity such as this.