The thermal diffusion properties of several different kinds of YBCO (yttriumbarium copper oxide) insulations and the quench properties of pancakecoils made using these insulations were studied. Insulations investigatedinclude Nomex, Kapton, and Mylar, as well as insulations based on ZnO,Zn2GeO4, and ZnO–Cu. Nomex, Kapton, and Mylar, chosen for their availability and ease of use,were obtained as thin ribbons, while the ZnO based insulations were chosen for their highthermal conductivity and were applied by a thin film technique. Initially, short stacks ofYBCO conductors with interlayer insulation, epoxy, and a central heater strip were madeand later measured as regards their thermal conductivity in liquid nitrogen. Subsequently,three different pancake coils were made. The first two were smaller, each using one metertotal of YBCO tape present as four turns around a G-10 former. One of thesesmaller coils used Mylar insulation co-wound with the YBCO tape, the other usedYBCO tape onto which ZnO based insulation had been deposited. One largercoil was made which used 12 total meters of ZnO insulated tape and had 45turns. Temperature gradients were measured and thermal conductivities wereestimated from these coils; the results obtained were compared to those for theshort stacks. Quench propagation velocity measurements were performed on thecoils (77 K, self-field) by applying a DC current and then using a heater pulse toinitiate a quench. Radial NZP (normal zone propagation velocity) values (0.02–1 mm s − 1) were two orders of magnitude lower than axial values (∼10–20 mm s − 1). Nevertheless, the quenches were generally seen to propagate radially within the coils, in thesense that any given turn in the coil is driven normal by the turn underneath it. This was dueto the fact that while the radial NZP is much lower than the NZP along the conductor (∼100 ×) the distance by which the normal zone must expand longitudinally is much larger than thedistance by which it must expand radially to reach the same point; in our case this ratio is ∼ 1600.