I sanded the interior area of this tray with an Arbortech Contour Sander to 220 grit. This is the first time I used this tool. I then stained the work piece. As you can see in the picture there are a lot of swirl marks and "pig tails". Does anyone what caused this? I wiped the work piece with Mineral Spirits prior to staining and none of these marks showed up at that time.P1010481.jpg