Apple was using a cellulose foam mixed with a starch based biodegradable binder, one that was very slightly different from Paperfoam to save them money on licen

Apple was using a cellulose foam mixed with a starch based biodegradable binder, one that was very slightly different from Paperfoam to save them money on licensing fees. Now they just use 99% compressed cellulose with a few antistatic additives.