Didn't Walter McCrone also claim that the Vinland Map was a fake?
Yes. And he was wrong.
In 1965, researchers at Yale University discovered a map that was thought to have been produced at least 50 years before Columbus’ first set sail looking for India and discovering America. The map, which showed Vinlandia Insula, (Island of Vinland) or as it is known today, Newfoundland. It was part of a small medieval volume, the Tartar Relation. The Tartar Relation had originally been bound together with the Vinland Map and another medieval volume, the Speculum Historiale. Wormhole alignments between the map and bothbooks clearly showed that they had at one time been bound together. The Tartar Relation volume was reliably dated by contemporaneous references to the Mongols (Katatas people) who dominated one end of Eurasia. There were also references to a bishop of Gada and Greenland that further corroborated the dating. It certainly seemed that the map was real.
In 1972, Walter McCrone, who would a few years later try to debunk the Shroud of Turin, examined some particles of ink from the Vinland Map. He found titanium anatase, a material that scientist first discovered in the 1920s. He thus concluded that the map was a recent hoax. He appeared on PBS and made a big splash.
Many scholars doubted McCrone’s conclusion. One was George Painter, the curator of ancient documents of the British Museum. In 1985, physicist Thomas Cahill, of the University of California at Davis, analyzed the map using a newly developed process: Particle Induced X-ray Emission. He found only minute traces of titanium anatase, amounts that were consistent with what would be expected in the common green vitoral ink of the fifteenth century.