Metallic proxies remain unsuitable for assessing the mechanics of microwear formation: reply to comment on van Casteren et al. (2018). Issue 7 (10th July 2019) - van Casteren, Adam; Lucas, Peter W.; Strait, David S.; Michael, Shaji; Bierwisch, Nick; Schwarzer, Norbert; Al-Fadhalah, Khaled J.; Almusallam, Abdulwahab S.; Thai, Lidia A.; Saji, Sreeja; Shekeban, Ali; Swain, Michael V.