There can be a few reasons why you are seeing swirls or “pigtails” when sanding. One of the most common is too much downward pressure on your sander or moving at too fast of a rate. Keep in mind that your sander requires just enough pressure to control it. Pressing down hard on your tool will not help sand your substrate any faster and can overheat your tool. Moving your sander rapidly back and forth will also cause swirls. When final finish sanding raw wood, keep in mind that you want a slow, steady advance of your tool with the grain of the wood. Because of the nature of orbital sanding, small circles will be evident when using coarser grit abrasives. As you move through your order of grits and progress to higher numbered grits (finer abrasives) it is necessary to move your tool at a rate of 1 to 2 inches per second to allow the finer grits enough time to totally remove the swirls made by the coarser abrasives and eliminate them.
For example, when sanding raw wood for stain, a good basic order of grits would be: 120, 150, 180, with SurfPrep Paper being the best choice for surface finish.
When sanding veneers, 150, 180, 220 and 320 (if necessary).
Another cause of sanding swirls is when you get buildup on your abrasive from sanding off an existing finish or sanding raw wood. One small piece of old finish attached to your abrasive surface can cause even the most experienced woodworker to experience sanding swirls. When this happens, grab that fingernail brush to remove these attached pieces or, switch to a new piece of abrasive.
A great timesaving tool to add to your Surfprep arsenal is one of our LED inspection lights. These high-powered LED light bars will show imperfections or swirls in your substrate that are often overlooked with the naked eye. It can be very discouraging when beginning to stain your project and you see the stain accentuate swirls that you may have missed. Examination under one of our inspection lights resolves this issue and will up your sanding game and your finished product quality. Inspection lights can be found at this link: https://surfprepsanding.com/product/led-inspection-lights/
