60% Compostable? What Does That Mean?
If you've ever contemplated a Flight Coffee bag while enjoying a cup of your morning brew, you may have read our sustainability statement and wondered what 60% compostable means. You have probably thought that the the tin tie and valve clearly are not compostable, but they don't make up 40% of the bag, so what's going on?
Actually, I wondered this one myself when we first ordered these bags. Fortunately, at this year's SCA Coffee Expo in Boston, I had the chance to speak with one of the VPs at the company that makes our bags and he explained the whole thing to me.
Like many more things than you may realize, the word, compostable, has a specific meaning in commerce. Just because something eventually biodegrades doesn't mean that you get to call it compostable. After all, even regular plastic biodegrades (in a few hundred years).
In order to advertise something as compostable, the material in question must meet a specific standard as defined by the American Society for Testing and Materials now known simply as the ASTM, an international standards organization. The standard in question is ASTM D6400. You can purchase the full standard from the ATSM website or you can read a summarized version here. Basically, to meet the standard (and legally call something biodegradable), the item must biodegrade within a municipal waste stream within 90 days. The test is pass/fail. Either the material fully biodegrades or it doesn't.
So, what does this mean for our bags? Well, according to the manufacturer, the bags are composed of three layers of material. Two of the three layers have fully biodegraded inside of 90 days, but the third has not. When you add the 1/3 of the bag that has not fully biodegraded to the tin tie and valve, you wind up with about 40% of the bag that does not meet the standard, hence 60% compostable.
The ironic thing is that that the three layers individually all meet the 90 day standard, but when they are fused together, something happens that retards the biodegradability of one of the layers. Furthermore, if you cut the bag up, all three layers will often meet the 90 day window, but the ASTM standard requires the bag to compost in its original form, you can't cheat by cutting it up or separating the layers.
So, what does this mean to you? Well, if you participate in a municipal composting program, the bag may not be welcome in the compost waste stream (check with your local authorities, YMMV). If however, you have a home composting program, feel free to toss our coffee bags into your compost pile. It may take a bit longer than 90 days, but our bags will fully biodegrade (not counting the valve or tin tie).
Sustainability is one of our core values. We'll continue to do what we can for the environment. Thanks for helping us try and leave the planet a little better than we found it.