Jesus,
Beware of creating too much heat from friction during polishing. Use a slow speed. Start on an underside surface if you can to learn what works best for you. Also, you said varnish. Is yours a solvent based polyurethane varnish, e.g. Minwax brand? Most of those are relatively rubbery/gummy which is why they have excellent abrasion resistance compared to older alkyl based formulations which will eventually cure very hard and thereafter polish very well. This same resilient gummy property makes them more difficult to polish than harder drying/curing finishes such as the water based lacquer finish shown in the link to Target Coatings site, which is based on acylic polymers much like those used in automotive finishes. The polyurethane finishes used on automobiles are also chemically cross linked, which makes them harder and tougher. I have the Menzerna products and several from other manufacturers, mostly 3M, which I have used with automotive finishes and with solvent based nitrocellulose lacquers on wood. They both work well You might do well to ask the manufacturer of the varnish what they recommend.
Dave R.
