Yes, it's for plants and yes, we had some pretty specific parameters! Please see my response to your original post on the "Tool" side of the house.
As stated in the article above, we had a host of complex factors to address in our design. The two primary issues are the incredible degrading natural environment of the northern Olympic Peninsula as well as the volume of materials and water being pushed through this machine (we're 30 years old as a company and just getting started…I expect this machine to last).
An additional, far more black and white factor for us to address are the federal regulations that require our products be manufactured with tools that feature non-permeable, non-leeching, solid surfaces that can be cleaned and sanitized with a validated method. It's this last point that makes some of our more utopian dreams just that. Utopian.
Welcome to our working compromise.
In a larger sense, this also fits our greater guiding philosophy as an herb company. Our intention has always been to provide local, sustainable alternatives to traditional herbs of commerce, those like goldenseal and american ginseng that have been all but wiped out of existence based on domestic and foreign demand. In a very real sense, we can only make the changes that our customers are comfortable with and support with their dollars.
As a result, education is a huge part of what we do. If you focus on the micro level, this washer may not as "sustainable" as some. It could be made from more reclaimed materials. However, this particular design allows us to model our particular philosophy to a wide audience of medical practitioners (our clients), who in turn have the opportunity to model and educate responsible and reasoned choices to a wide range of people.
So, in looking over the trees to see the forest, we're quite proud of our design as it supplements our attempts to address issues of botanical conservatism and activism. It's value extends far beyond the numbers I can collect on paper.
I hope there was something in this response that resonates with you, as your question allowed me to discover those pleasantly unexpected unconscious connections that sometimes occur when we put our faith in the intentions guiding our process.
Please read our discovery post in the "idea" section of the pedal powered root washer tool page. We've finally completed manufacture on a stainless steel, re-envisioned drive-train that is robust and capable of meeting all we need to remain a federally compliant production facility. Enjoy, and I look forward to joining to conversation! (http://farmhack.net/forums/bike-powered-root-washer-v-20)