A Merry Christmas To All

Started Dec 24, 2012 | Photos thread
bassotto Regular Member • Posts: 272
Re: A Merry Christmas To All

vincent W wrote:

Hi Bassotoo

How's going on about your replacing CMOS glass filter?

Is there any new information about the spare part sensor filter?

I ever checked that the glass might be coated by MgF2 coatings, which might be etched or even exchanged under humid condition.

If you could, try some dilute HF solution to swap on the white spots for dissolving them.


It is believed the Na+ ion was migrating into MgF2 layer to replace the Mg into NaF.

MgF2 + 2Na --> 2NaF +Mg 2+

after the contacting to humid air, the water molecule react with Mg

Mg2+ + 2H2O --> Mg(OH)2 + H2

The magnesium hydroxide was appeared as white powder such like the white spots on filter surface.

You can try this using the broken filter to ensure the phenomena described.

Good luck

Hi Vincent,

sorry for the late replay, from where the Na in the reaction?

I can note that usually spots are on the internal surface of the filter and this could maybe be in relation with the heating of the sensor and the presence of air-humidity between the sensor and the filter itself.

When I find enough time I will try to use dilute HF solution (I have it but it is an operation a bit dangerous ) just for curiosity

As you can see I opened a new trhead about filters.

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