Auctioneers use many special types of marker.  The average marker doesn't give a dense mark and is made for consumer use.  We have a line of special "industrial" markers that are formulated for specific uses such as auctions.  The marks our markers lay down are dense. They don't fade quickly. In fact on certain materials like Tyvek tags our marks will last years.  We recommend our industrial markers for auctioneers. Our "B" line of paint markers are an auto auction and window favorite.