On 7/18/2017 11:52 AM, rbowman wrote:


I worked for a company that made the polystyrene foam clamshells for
McDonalds. One of the advantages of thermoplastics is you can grind the
defective product and feed it back into the line. The clamshells had a
tan color rather than the pure white of virgin styrene, part of which
was due to the amount of regrind being used. McDonald's is a very
demanding customer and would use colorimeters to ensure the product was
the same exact shade. If the process was running right and there wasn't
much regrind that required tinkering.

That whole history is educational. McDonalds went from the original
paper wrapping to foam to save the trees or something. Then they went
back to paper/cardboard to save the landfills. Both were marketing
decisions based on what the public's perception was at the moment.

I've been out of that industry for a long time and don't know what is
used today but we were using freon by the railroad tank car for the
blowing agent. That wouldn't fly today. The best part of the job was ice
cream cones were made in another part of the plant. You could eat the
defective parts. Sugar cones hot off the press are good!



I worked in foam plastics for 47 years. Our blowing agen was pentane.
About 15 years ago we had to capture emission, but it did not have the
bad rap that CFCs had. Nevertheless, all foam plastics were bad to an
uninformed public.