Whitish plaque on bricks - how to clean

[merman]

Sorry if this question has been asked before, but I could not find a specific topic on cleaning Lego.

I disassembled my 10226 Sopwith Camel and was a bit shocked to find the big green plates being pretty dusty. So I removed the dust and then found out there was a whitish/greyish plaque underneath. We have a small house with an open kitchen.

So I tried to clean it three times, using laundry detergent and dishwashing detergent and with a paint brush, sponge and toothbrush, but nothing helps. You can see a difference where the plates were exposed to fhe air and where ofher plages were stacked.

The plaque can only be seen under a certain angle and light. Is fhere a way to make my plates shiny again or is this a normal deterioration that happens throughout the hears? I also noticed it on my 75059 UCS Sand Crawler.

Edited March 23, 2016 by merman

[Hinckley]

I found this one time only on an eBay auction of Fabuland figures. I healed them with olive oil. I'm sure there's a better way but that worked for me.

[SpiderSpaceman]

I got that on my 2001 Bionicle sets years back. I dunno. I'd say hard water deposits if I'd ever washed them, but I didn't, some grimy grime. Maybe just dust that caked up from air moisture?

[merman]

Yes may be caked up moisture and dust. But how to remove? See pic

http://i235.photobucket.com/albums/ee236/hellomrzebra/Mobile%20Uploads/image_zpsyvhltmv0.jpeg

[Giantorange]

Might sound strange, but have you tried toothbrush and toothpaste - it's a VERY mild abrasive.