Environmental Impact of the Materials Used in Blow Molded Plastic Products

Plastics often get a bad rap when it comes to being environmentally friendly. In many ways, this is a misperception. This article takes a closer look at the environmental impact of the resins commonly used in blow molding.

High-density polyethylene (HDPE)

HDPE is the most widely used household plastic material and the most common resin used in blow molding. Examining the raw materials that go into making HDPE resin, 188 pounds of crude oil is used to produce 1000 pounds of resin. Other popular plastics, such as polystyrene, which is commonly used in injection molding, require 3.75 times more crude oil to produce the same amount of material. Americans throw away 25,000,000,000 styrofoam coffee cups made from polystyrene every year.

Further, HDPE is on many white lists for the best plastics for consumers because it doesn’t leach harmful chemicals, such as BPA, into the environment or into the contents it contains.

HDPE plastics are so commonly recycled that their resin code, 2, used to be part of the universal recycling symbol. Over one billion pounds of HDPE bottles alone were recycled in the United States in 2014. Also, HDPE products are normally built to last, which improves their sustainability over less durable plastics that are continually disposed of and replaced.

Polyethylene Terephthalate (PET)

PET is most often used in blow molding clear bottles. Only 215 pounds of liquid natural gas is needed to produce 1000 pounds of PET resin. Of the most common plastic types in commercial use, PET is recycled more than any other.


Polypropylene (PP) is a good plastic commonly used in blow molding. It’s a low-density plastic, so for comparable volume, it can have a lower environmental impact. PP produces less solid waste than many other popular types of plastic. Also, like HDPE, it’s BPA-free.

PP recycling has increased over the past decade, skyrocketing by 32% from 2012 to 2013. Because it is a very flexible plastic, it can be recycled into versatile new products, from new blow molded products and clothing fibers to battery housings.

Source for raw material data: American Chemistry Association

Sustainability is system-wide

Assessing whether a certain plastic in your blow molding project is sustainable goes beyond choosing the most eco-friendly type of resin. Level of sustainability is a big-picture metric, which takes many things into account:

  • Sourcing — from type of resin to where resins come from, including the greenhouse gas emissions of production
  • Energy expenditures — from how efficient a blow molding machine is to how energy use is managed company-wide
  • Waste management — from reducing physical waste throughout the blow molding process to creating a company culture of waste reduction and recycling
  • Import, export, and transportation effects — from a blow molding supplier’s commitment to sustainable trade partners to how much fuel a chosen shipping method requires

These factors (and more) interact to create a complex, often-changing portrait of what it means to be sustainable.

Custom-Pak has been a leader in environmentally sustainable blow molding for over 40 years. Our recycling facility recovers two million pounds of plastic per month. Looking for more information? Check our page on Stewardship & Recycling.