Shamrock and Emerald were budget reel to reel tape brands manufactured by Irish / Ampex through the 1960s to 1980s. According to experience, the quality of these tapes varied tremendously, depending on when and where you bought them. Mostly they were non-spec tapes based on regular Ampex formulations. We have identified 8 generations of this tape, and this one offered is the first type we identified:
Early generation mylar tapes are based on the standard (type 1) tapes sold by Ampex in the 1960s and early 1970s. These are still playable and have no sticky shed. You can identify them through their oxide color (brown) and that they have no back coating. These are the most reliable Shamrock tapes, and we offer these as refurbished with their formula called out (Shamrock Type 1: Ampex Ferrosheen Brown Oxide). The DP version is a little shorter at 2250ft, but this tape seems to perform very well.