How do I clean my new Hoya ND400 filter?

[HPS3]

Yesterday I received my new ND filter and my DD grabbed it and got smudges on it. I tried just using a lens cloth but it feels like there is a coating on the filter that just won't allow it to come clean. Are there any tricks? Should I try just water? My other filters don't seem to have this coating on them.

 

[boBQuincy]

Mine came with a small smudge on it and cleaning made a real mess. It took many attempts with lens cleaning fluid and lens cleaning tissue to get it clean. After that I returned the filter and bought a B&W, figuring the Hoya would be a real problem in the field if (when) it got a smudge.
Others use them so maybe the problem is not that bad.

 

[ssanders79]

Try calling or emailing the US support and asking for advice

THK Photo Products, Inc.
7642 Woodwind Drive, Huntington Beach, CA 92647
Tel: 714-849-5700 Fax: 714-849-5677
support@thkphoto.com

I just picked up some shade 10 welding glass to experiment with a ND filter as my other ND filter does not provide enough stops.

 

[HPS3]

Thanks for the info. I am going to try and clean it again. If its a pain I may just return it and get the B+W.