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Background

For the past several years, I have cooked rice and pasta in my microwave instead of on the stove. This involves putting the rice or pasta in a bowl of water and then using the automatic rice or pasta program in the microwave.

When I do this, the microwave exhausts some of the water vapour from the bowl out onto the surface that the microwave is sitting on, leaving behind damp patches.

The problem

Unfortunately, I haven't been cleaning up this wet residue after each use. As a result, the surface that the microwave was sitting on has developed a white stain. The microwave has lived on both a piece of wooden furniture and also a laminate benchtop, and both have developed these white stains.

Stain on laminate benchtop

This one is faint, but if you look closely near the bottom section, you can see lots of little pale white patches.

White stain on laminate benchtop

Stain on wooden furniture

White stain on wooden furniture

What I've tried

I've tried the following to remove the stain, and none of these worked:

  • Wiping over with a wet cloth
  • Wiping over with soap
  • Wiping over with dish-washing detergent
  • Wiping over with vinegar
  • Scraping off with a scourer
  • Soaking in dish-washing detergent

I haven't tried bleach since I read that it can take the colour out of the furniture and benchtop.

The question

What is this white stain? Is it some sort of mould? Or could it be starch from the rice? Or something else?

How can I remove the stain?

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The way I understand the pictures is that whatever you see is not a stain at all. The material of the furniture has wore off - i.e. it was removed due to all the humidity, heat, cleaning...

The if this is the case, then you have few solutions.

  1. Replace the element. Contract a local furniture making company, they might be willing to help.

  2. Live with it. If it is not (very) visible - maybe hidden under the microwave, then there is no harm in just forgetting about it.

  3. Apply an adhesive foil on top of the board, with any model that you choose - wood, marble, metal... Be careful that this foil might not be suitable for high temperatures - study the situation carefully first.

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  • Is it normal for wooden furniture to be bright white under the surface? I've looked over the outside and internals and can't see white anywhere else, so I wonder if it's something else?
    – Sam
    Jun 7 '20 at 4:01
  • It is possible that the wood is actually not natural wood, but some artificial something, covered or painted to look like wood. Sometimes the imitation is so good, that it is surprising. Only a "healthy" cut or drill somewhere in the volume of the wooden board can tell you the truth. If you want to make the experiment, just drill a hole on the underside, where it will never be visible (of course, be careful not to reach the other side, which will make it very visible). Analyze what you see and draw the conclusions. Maybe tell us too :)
    – virolino
    Mar 17 at 16:16
  • Another way to test the reality is to use some sandpaper, and rub the affected area. Either you will start seeing more wood, or you will start seeing more white. The surface is pretty damaged anyway, so a little additional damage will not be very noticeable.
    – virolino
    Mar 17 at 16:20
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The second picture, the wood looks varnished, which will bloom if subjected to repeated steaming. Is the wooden top actually veneer or solid wood? It looks like permanent damage [bloom] to the varnish, which may now be penetrated, allowing limescale buildup in the wood-grain itself, making it a compound issue. I think that's a job for a sander & a new varnish… assuming it's even solid wood & not veneer, which is likely too thin to stand much sanding.

You might gain some slight improvement by treating with standard descaler [long soak for maximum penetration], then oiling or waxing the surface. That may mask it but not fix it. If the varnish is badly bloomed then removal is the only real fix.

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The stains on the wood surface look like they can be scraped off. You could try a glass cooktop scaper like this:

enter image description here
Image source

Don't use any force and be careful not to damage the wood. There also seem to be scratches in the wood already. I doubt you could remove the residue from them.

Don't use such a scraper on the laminated surface, it will definitely damage it.


Another possibility is the good old baking soda and acid detergent.

  • Sprinkle a generous amount of baking powder / soda over the stains
  • Add lemon juice or vinegar to the powder. You can use a spray bottle or mix and spread a paste directly on the surface.
  • Let it sit for 10 minutes before wiping it off with a moist cloth and clean water.

Another site recommends soaking the stains in olive oil for 10 minutes and then scraping the stains off with a spoon. This should work with hard, crusty stains like limestone, but from your pictures I'm not sure it's applicable here.

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  • 1
    did you try to use that scraper on a wood surface? I remember that I tried similar stuff in the past and the wood surface was damaged. I think that it creates more problems than solutions.
    – virolino
    Jun 2 '20 at 11:50
  • I used a tough scourer to try to remove the white stains from the wood, and it didn't affect them. If anything, it seemed to scratch into the wood, but there was still white underneath.
    – Sam
    Jun 7 '20 at 3:57
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If the white is starch, then apply amylase and leave overnight. A cheap accessible source is saliva. Try dribbling a bit at one spot and leaving overnight.

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