Cleaning the Plastic - TechforTrade/Thunderhead-Filament-Extruder GitHub Wiki

Cleaning the plastic can be time consuming and labor intensive so start with plastic that is as clean as possible. Bottles that cannot be easily cleaned should be passed on to another recycler.

Step 1: Sort the plastic. Sort by color and if possible by type. Bottles of the same type will be more likely to produce more consistent filament.

Step 2: Remove the labels. This must be done 100% perfectly. Any bottle with little bits of label remaining MUST be discarded. We remove the labels by dunking the capped bottle in boiling water. The label glue will soften and the label can be pulled off in one piece. The cap is kept on the bottle so that as the walls of the bottle soften, the ridges are somewhat removed. This makes using our chopper easier. NOTE: Do not store bottles in this state. The remaining label glue will collect contaminants

Step 3: While the bottle is still hot, remove the label glue. We have found that the easiest way to do this is to wipe it with an oily rag while it is still warm from delabeling. The oil mixes with the glue. Heat speeds up the process. When the glue has mixed with the oil, soap and water are effective for washing.

Step 4: Wash the bottles with warm (if possible), soapy water. Change the water as it becomes dirty.

Step 5: Rinse the bottles with clean water and inspect.

Step 6: Store the bottles in a clean container until they are ready for grinding. The bottles do not need to be dried as water helps to cool the cutters of the grinder.