Marc, Yuhang, Michael, Aso

This morning, we took the mirror out of the water bath. Then we dried it with an ion gun.

We inspected the HR surface and found that stains get much fainter but still there. Therefore, we decided to continue the cleaning for another 24 hours.

Example1: splash like stains near the bottom of the mirror

Before cleaning

After cleaning

Example2: a stain near the center

Before cleaning

After cleaning

Some stains such as an arc like stain seen in the 2nd photo remain almost intact.
I hope we can remove such stains with first contact.

If it was not possible to completely remove the remaining stains with the ultra-pure water system, we need to try something else.

One possibility is to use the water spot pretreatment (WSP) with first contact.
http://www.photoniccleaning.com/product-p/wsp1.htm

I'm asking for quotation of this product now.