To many collectors putting their prized comics in polyethylene bag, thinking ” this is a good enough preservation
move, until they come back to their comic in a few years to find the quality of their book has changed for the worse.
While polyethylene bags are OK for short time comic storage, perhaps over a few months to a few years. Comic aging depending partly on the climate where the comics are stored. Polyethylene are not considered a safe long term archival quality solution to document preservation. Polypropylene is considered a better encapsulation method because generally it is more stable in structure than polyethylene. In the end although polyester film encapsulation is considered the best for the value.