I thought I would share a painting tip on covering up those UGLY brown and red spots that show through the paint when painting a vintage piece. Sometimes, chalk paint will cover it up if you use several layers of paint.
However, if you want to take the easy way out...buy a spray can of shellac. I prefer Zinsser Bulls Eye Shellac in Clear. Just spray it directly on the spotted area and let it dry for approx. 15 mins.
Paint back over the Shellacked area and voila....spots are gone!
The Shellac acts as a barrier. It has worked for me every single time!