Here is a link to an image of a floor that we just had refinished for one of our clients. I watched them sand diagonally to get the previous check marks out of the floor and then sand with the grain.

In this image it appears that there are lines every 6" or so across the grain of the floor. I am not sure if it got worse after the 2nd coat but I thought it was the applicator at first. I did not see the finishers sand against the grain which is what it looks like in the photo.

It is more visible when the sun shines across them. Without the sun and under normal artificial lights the floors look great and the old check marks from the previous sander are not noticeable.

I need help identifying what could have caused this so we can get it corrected. The only thing I think of is the screening between coats caused this and it is every 6 in since that was the pattern they took going back and forth.

We also used a high traffic water based poly.

Here is a link to the image and would like advice on how to imbed the image in the post as well.

https://public.3.basecamp.com/p/E3kYJ7P ... ZEACovtmbX

Thanks in advance for the help and if your answer helps solve the issue, I would like to share on my blog etc to help you and your business out.

Looks like sanding technique. Use a satin or matte finish to reduce reflection and not be noticed.