Frnak McKenney fired this volley
in :

Thanks for the pointer. It turns out that I was wrong on the "cart"
being polyethylene, although I haven't figured out exactly what it
_is_ yet. I know it does crack -- there is one small one where a
bolt holds the belly-band lift support tubing in place -- and the
color and surface have a "weathered" appearance.

I'm not sure what you've described rules out polyethylene. PE oxidizes
and is deteriorated by sunlight. When it does, it achieves that
"weathered" appearance - rough, grey, pourous, dusty - and begins to
crack easily.

So... what else make you suppose it isn't PE? It should have a recycling
stamp somewhere on the bottom indicating which one of several general
types of plastic it is. If it's PE, it will say so; same for
polypropylene. Mixed resins will carry a number.

LLoyd