Sharp microwave - 'burn' marks on door and chassis

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geekIT

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#239989 14-Aug-2018 11:16

Sharp microwave about 18 months old. Model R-340R(W) 1100w.

Over the last 6 months some 'burn' marks have developed on the inside of the door and chassis.

These marks match up, i.e., a mark on the door matches one on the chassis.

There are four in total - two on the chassis and two on the door.

Sorry, they're difficult to describe, but if your microwave has done this, you'll know exactly what I mean.

They're more like 'scrapes', actually. 40-50mm long. As if someone has scratched the surface down to bare metal.

Any ideas as to what has caused it? And what I should do about it?

'Those who can make you believe absurdities can make you commit atrocities.' Voltaire

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tdgeek

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#2073218 14-Aug-2018 11:38

I have a burn mark between and on the door and cavity, caused by me starting it and forgetting to put the food into it. Possible in your case?

Gordy7

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#2073225 14-Aug-2018 11:52

Difficult to diagnose without photos and close inspection...

Really need an expert to assess..

But my 2 cents worth:

- Damaged door gasket?

- Distorted door?

- Worn hinges and latch?

- Opening the door before microwave stopped... poor safety switch/shutdown switch positioning..

- Cooking pies etc, in metal dishes...

Gordy

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geekIT

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#2073263 14-Aug-2018 13:28

Gordy, thanks. But I think tdgeek might've nailed it.

Methinks it's a mybad :-(

We make up our own Skim milk in used Leggo sauce bottles.

After they're empty and washed (by hand, no dishwasher) I usually sterilize them for 2 minutes in the microwave.

Nothing else in there except the wet bottle sitting on a damp wettex to stop it rolling around.

Never thought about the 'no food' situation. Maybe it's getting overheated? Duh.

'Those who can make you believe absurdities can make you commit atrocities.' Voltaire

'A patriot must always be ready to defend his country against his government.' Edward Abbey

tdgeek

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#2073266 14-Aug-2018 13:39

geekIT:

Gordy, thanks. But I think tdgeek might've nailed it.

Methinks it's a mybad :-(

We make up our own Skim milk in used Leggo sauce bottles.

After they're empty and washed (by hand, no dishwasher) I usually sterilize them for 2 minutes in the microwave.

Nothing else in there except the wet bottle sitting on a damp wettex to stop it rolling around.

Never thought about the 'no food' situation. Maybe it's getting overheated? Duh.

Microwaves are the size of your little finger. They bounce around and get absorbed into moisture, then gone. They excite the moisture molecules which heat up. Food has moisture as does your wettex towel and damp bottle, but that will soon be steamed, leaving little moisture, then they run wild.

Coil

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#2073285 14-Aug-2018 13:59

Can someone explain this microwave sterilization technique?
Sure if it turns water on the surface to steam but it wouldn't compare to a steam cleaner.

tdgeek

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#2073289 14-Aug-2018 14:07

Coil:

Can someone explain this microwave sterilization technique?
Sure if it turns water on the surface to steam but it wouldn't compare to a steam cleaner.

Water boils so that sterilises?

SpartanVXL

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#2073293 14-Aug-2018 14:18

I have a friend who did this, till I pointed out that until all water boiled and all surface area of the item had water to be boiled that he wouldn't be getting everything. It was good that he understood some basic science.

He used to do this to every kitchen cloth instead of washing them properly. I very quickly pointed this out to him and stopped using any of his kitchen cloths to dry anything. He went back to not being cheap, and using detergents/laundry powders.

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wellygary

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#2073299 14-Aug-2018 14:32

geekIT:

Gordy, thanks. But I think tdgeek might've nailed it.

Methinks it's a mybad :-(

We make up our own Skim milk in used Leggo sauce bottles.

After they're empty and washed (by hand, no dishwasher) I usually sterilize them for 2 minutes in the microwave.

Nothing else in there except the wet bottle sitting on a damp wettex to stop it rolling around.

Never thought about the 'no food' situation. Maybe it's getting overheated? Duh.

Stick the glass jars in a regular oven, it is likely more thorough....

You are relying on the water heating to a boiling point to then heat the glass and therefore kill off bacteria etc

There is no non-heating sterilisation that occurs, - see this paper...

http://aem.asm.org/content/53/9/2133.full.pdf

tdgeek

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#2073300 14-Aug-2018 14:38

as we know Microwaves don't heat evenly. Anything that reached boiling point and steamed should be sterile, but ever heated something cold and ate it without moving it. Ouch hot, then ouch cool

Aredwood

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#2073311 14-Aug-2018 14:55

geekIT:
Gordy, thanks. But I think tdgeek might've nailed it.

Methinks it's a mybad :-(

We make up our own Skim milk in used Leggo sauce bottles.

After they're empty and washed (by hand, no dishwasher) I usually sterilize them for 2 minutes in the microwave.

Nothing else in there except the wet bottle sitting on a damp wettex to stop it rolling around.

Never thought about the 'no food' situation. Maybe it's getting overheated? Duh.

This will be the problem. You are putting over 1KW of radio frequency energy into a small space. With nothing to absorb the energy. (after the water evaporates and the fan removes the steam) Which will be why arcing is occouring between the door and case. It can also destroy the magnetron.

Use Sodium Percarbonate mixed in water for sanitizing your bottles. You can buy it from shops that sell homebrewing supplies.

geekIT

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#2073412 14-Aug-2018 16:37

Aredwood:This will be the problem. You are putting over 1KW of radio frequency energy into a small space. With nothing to absorb the energy. (after the water evaporates and the fan removes the steam) Which will be why arcing is occouring between the door and case. It can also destroy the magnetron.

Use Sodium Percarbonate mixed in water for sanitizing your bottles. You can buy it from shops that sell homebrewing supplies.

OK, I get it, thanks.

Re sterilizing solutions, I occasionally leave the bottles overnight filled with a weak mixture of Janola and water.

'Those who can make you believe absurdities can make you commit atrocities.' Voltaire

'A patriot must always be ready to defend his country against his government.' Edward Abbey

tdgeek

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#2073445 14-Aug-2018 18:10

geekIT:

Aredwood:This will be the problem. You are putting over 1KW of radio frequency energy into a small space. With nothing to absorb the energy. (after the water evaporates and the fan removes the steam) Which will be why arcing is occouring between the door and case. It can also destroy the magnetron.

Use Sodium Percarbonate mixed in water for sanitizing your bottles. You can buy it from shops that sell homebrewing supplies.

OK, I get it, thanks.

Re sterilizing solutions, I occasionally leave the bottles overnight filled with a weak mixture of Janola and water.

Its a great suggestion, brewers need it very clean and sterile.

Gordy7

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#2073451 14-Aug-2018 18:18

Maybe an option is to use a pressure cooker to steralise the bottles...

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

Coil

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#2073452 14-Aug-2018 18:18

SpartanVXL: I have a friend who did this, till I pointed out that until all water boiled and all surface area of the item had water to be boiled that he wouldn't be getting everything. It was good that he understood some basic science. He used to do this to every kitchen cloth instead of washing them properly. I very quickly pointed this out to him and stopped using any of his kitchen cloths to dry anything. He went back to not being cheap, and using detergents/laundry powders.

tdgeek:

Coil:

Can someone explain this microwave sterilization technique?
Sure if it turns water on the surface to steam but it wouldn't compare to a steam cleaner.

Water boils so that sterilises?

This was my exact thought process.

tdgeek sorry maaaate.

Goosey

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#2075133 18-Aug-2018 08:40

When the young one was a baby, we used this...

https://www.philips.co.nz/c-p/SCF282_01/avent-microwave-steam-sterilizer

We know lots of people who have these....

never tried to sterilise anything else other than baby bottle stuff though.....