Hi Dave... heres a quick description >From http://www.woodfinishingenterprises.com/coating.html ABRASIVES ............. Rottenstone is a very fine abrasive powder used to obtain a high gloss on finishes by rubbing the surface with rotten stone and water or oil. To obtain the highest gloss on varnish, lacquer or shellac finishes, it is recommended the surface first be rubbed with pumice and water or oil.
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