I was given a flow hive that had been left standing for a couple of years. As a result the hive tool couldn’t move the seized sections up or down. due to propolis gumming up the works. I tried freezing and washing in hot water which removed most of the old wax and honey but still left the propolis in situ. I stripped the frames to their component parts and immersed them in a weak solution of caustic soda overnight then washed and brushed them to remove the softened gunge. After a thorough rinsing to remove any caustic soda residue I blew dry the parts and reassembled them. Very fiddly and tedious as I had all the frames to clean. End result was the mechanism worked perfectly, looking like new. All propolis removed and a very smooth action.