Feb 112007
 

The oth­er day Tim brought home some food in a con­tain­er that claimed to be made of corn and there­fore com­postable. I was intrigued by this, since I remem­ber going to street parties and Christ­mas mar­kets in Ger­many where the dis­pos­able plates were grain-based and even edible (not that people usu­ally did eat them) but haven’t seen them here. So I looked into it a bit more.

The con­tain­er was made out of some­thing called PLA, which is made from starch. The label said not to microwave it, which had me puzzled — isn’t corn safe to microwave? What would hap­pen? Would it melt? I tried microwav­ing some water in the con­tain­er and noth­ing unto­ward happened, so I poked around on the web­site for the com­pany (Nature­Works LLC, a sub­si­di­ary of Car­gill) to find out more.

The web­site did­n’t give any details that I could find as to why not to microwave the con­tain­er, so I emailed them. And got back a rather mixed reply. Some breath­less mar­ket­ing prose (new, revolu­tion­ary, bridges the gap between nat­ur­al and syn­thet­ic products), the actu­al answer in the middle, a some­what odd para­graph about how all the tech­nic­al info they’re pre­pared to dis­close is on the web­site (if the answer to the microwave ques­tion had been there, I would­n’t have emailed them). Any­way, the answer is sup­posedly that PLA has a low melt­ing point, so the con­tain­ers might leak in the microwave. 

Next Step

So if this con­tain­er is com­postable, where can one com­post it? The store has a big bin to take them back, but what about the Van­couver com­post facil­ity? Or indeed my com­post bin? The cash­ier said “oh, just throw it in your com­post bin.” “Are you sure?” “Yes, abso­lutely”. Accord­ing to the PLA bro­chure, you need 140ºF and humid­ity between 80% and 90% for exten­ded peri­ods of time. So that rules out my com­post bin. And the Van­couver City com­post facil­ity as well, unfor­tu­nately, since they use an open win­drow pro­cess. I emailed the rel­ev­ant people in the Van­couver City engin­eer­ing depart­ment, and they poin­ted out not only would it not com­post, if I put the plastic in the yard waste bin, it might encour­age oth­er people to put unsuit­able plastic con­tain­ers in there. So it’s back to the store with the con­tain­ers; for­tu­nately it’s not a big deal since it’s one of the loc­al stores we shop at anyway. 

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