A5.13 is (now) the specification for Nickel and Cobalt coated electrodes. It used to also contain the Ni and Co bare rods for GTAW and OFW, but those were recently moved to A5.21.
These type of rods are usually made utilizing a continuous casting method. The alloy materials are melted in an electric induction furnace and then cast through an appropriately sized die to form a continuous length of rod. The rod is then cut to length for welding (14", 28", 36" or 6 foot lengths).
Hope this helps,