Last Updated: June 16, 2018
1. Flat Edge
The very earliest 12″ microgroove Blue Note LPs (1956/7) were pressed without the slightly raised profile to the edge of the central label area – called a “groove guard” – which is found on all later pressings. The first pressings of BNLP 1500-1557 all have a flat profile, and none after.
The flat edge also refers to the finish of the outer edge of the vinyl, a trimming process by which excess vinyl extruding from the stampers is cut off immediately after pressing .
As seen on this copy of BN 1530, the vinyl rim was trimmed at 90 degrees, a straight vertical cut, leaving a “flat edge” the thickness of the vinyl, though lightly chamfered at the top and bottom edges so as not to leave sharp corners.
2. Beaded Rim
Flat edge was succeeded by “beaded rim” as found on most records today and in the following fifty years, where the edge of the vinyl is trimmed to a smooth rounded edge, the profile like the letter “D”.
(Added picture below for a permanent home on these pages)
Flat Edge vs Beaded Rim
The waste vinyl left after trimming is contentious, as some plants added this waste vinyl back in the pressing of future records, adulterating pure vinyl to reduce cost.
Vinyl production process (wiki)
3. Serrated Edge
Another “anomaly” found on a small number of Blue Note re-issues in the Liberty Years (1966-70) is the serrated edge, which was characteristic “trademark” of one pressing plant, believed to be Keel Mfg. Corp. of Hauppage, Long Island, N.Y. (long since defunct)
The significance of serrated edge is close to zero, however it is not “negative”. This pressing was pressed from an original Van Gelder Stereo master. I have five Division of Liberty pressings with serrated edge out of about fifty Liberty reissues. Uncommon, but not rare.
Since Liberty had records pressed at at least two locations and eventually at multiple locations, copies of the same title will be found with and without serrated edge.