Replaced mirror, defect again from cleaning?

Hello guys,

I got a replacement mirror a while ago and printed 2 parts before with it and it was succesfull. Today I had to clean my mirror as it had a lot of dust on it. At first with a dry pec pad. The after realizing there was some dust left my dry pec couldn’t remove I took one with a bit of IPA (99.9%). I wiped carefuly as long as the oily leftovers werent’ visible anymore. What I can see now are definatley some small scratches again. I did not want to clean my mirror as I was expecting this again but I had no choice due to the amount of dust. Again I guess my mirror is defect and again I don’t know what I did wrong! I am printing a model at the moment and I expect it to be a fail. Anyway I can see new scratches on the mirror and I have noe idea how to keep my mirror clean no matter how careful I am. Is there anyone who is through this as well? I can’t be the only one.

okay I did two prints and they were successful! the 5 butterflies and another bigger part. Anyway I can definately see some tiny scratches. To my experiences this kind of defects led to failed prints in the past but not this time. I have learned a lot about this printer but to keep the mirror clean is the most challenging. The worst thing about the form1+ is that you can never expect the next print to be succesful. I was hoping to have a printer that is predictable in the quality of the prints - no way to have customer orders.