I built a farmhouse table with Douglas Fir, applied Saman water-based stain, and then applied the first coat of water-ased finish. The folks at the store said I should sand after the first coat, using at least 220 grit sandpaper, which I did, using my random orbital sander. But the sanded surface is now full of milky white scratches, and in a couple of smaller patches the stain came off. What did I do wrong? Should i not have sanded, or did I sand too hard or should I have used a finer grit? Finally, do I need to start all over again and re-stain the table?
sanding between coats should just be a light rub, usually it's less effort to use a hand block, or a sanding sponge than to lift a power tool, you only need to remove the sheen, when the paint looks mostly dull that's enough rubbing.
Water based finishes can take considerable time to set, especially during cold or humid weather. If you ignored the makers advice for suitable painting conditions you will have to wait longer than the label suggests for the paint to be hard enough to sand.