Medium deep (2/3 Langstorth) frames are made of food grade polypropylene, designed and manufactured by Honey Paw.
Due to narrowed top and bottom bars, there is 10 % more cells in the medium deep plastic frames than in comparable wooden frames. In spring a hive is able to keep warm a larger number of bee embryos and furthermore, there will be more space for honey. in addition, the plastic frames withstand extracting of thixotropic (heather) types of honey excellently.
For a short time polypropylene frames can withstand heat up to 115 ºC (239 ºF), so that they can be treated by steam with a grain of salt. The new frames tolerate steaming well, but a part of frames can loose their form in a long run. This is caused by absorption of wax into polypropylene. In addition, during a longer period the frames can bend or curve capriciously. Mesimestari is not liable for the damages caused to the frames.
The frames can be cleaned using a metal spatula to separate the honeycombs apart from the frames and smelting them. After that the frames will be washed by a steam pressure cleaner, and reused. The polypropylene frames can also be retted in cold water with caustic soda overnight. After that the frames will be cleaned with water and a dishwashing brush. Or the frames can be cleaned only taking honeycombs apart with a spatula and after that reused again.