Yes you can spot shellac. First start out with a little shellac with a drop or two of linseed oil and french polish the area. Keep doing this many times until the area is level with the rest then French polish to blend in. You may want to use the amber shellac first to darken the water ring then use clear to finish the repair. You can also use a fine artist brush and brush the shellac on in thin coats until it is level with the rest of the finish. Waiting about an hour between coats, should only take about three thin coats. Then You can french polish the area smooth. After a week of curing wax the entire cabinet with a good quality past wax. I use Bri wax.
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