For those that read my blog with any kind of regularity, you know that I sometimes venture rather far afield from the normal thinking when it comes to potential biochar applications. This weekend another one of ‘those’ ideas snuck into my brain.
I blame this latest rabbit hole that I fell into on my daughter’s 4-H group’s recent DIY solar charger project which got me interested in other DIY solar ideas. Not only did I invest considerable time this past weekend checking out various Instructables, Pins, & YouTube videos on how to convert soda cans into solar heating panels but I also learned that soda cans aren’t really the Holy Grail for solar optimization (no surprise there I suppose). Interestingly one series of videos showed how simply spray painting plywood first with shiny, then with matte spray paint would do a better job colleting solar heat than the aluminum cans. Then the guy threw in some steel wool which he proceeded to spray painted black to increase surface area for solar absorption. So really what is needed is something black with a lot surface area.
Hmmm now let me see, do I know something that fits that description? Why yes, yes I do. A little something called biochar! Which of course got me wondering if biochar paint might be a possibility. Well thanks to Master Google and Mother Earth News, I have learned about the basic elements of paint and thought I’d give biochar paint a whirl.
Wanting something easy to start, I discovered flour paint which uses flour as the binder and clay as the pigment and filler. I simply substituted char for both the clay filler and the additional filler listed on the recipe. (I do wonder if the char might act as some type of mold deterrent if the flour doesn’t clog up all the pore spaces). The key quality for the char, or any coloring agent for that matter, is that it has to be really, and I mean really finely ground which can be a challenge for certain kinds of char. My first batch used coffee chaff char which turned out to look a bit like black stucco or perhaps asphalt. Not terribly pretty but still interesting properties nonetheless. The picture shows a plain piece of wood painted twice with the char flour paint. It definitely has a lot more surface area than mere spray paint and seems to absorb heat rather efficiently for such a low tech object.
I also tested a much finer grained biochar made from grape seed extract which produced a much darker shade of black paint. As I am suffering from poison ivy for the 2nd time in a month, I decided to paint some on the affected area. I have to say it helps stop the itch but it looks like I rubbed my arm in black grout. Anyway this got me thinking that this stuff might eventually find a use as post-pruning or wound care technique for trees too.
Next I may try making a char-based tempera paint and then perhaps graduate to more complicated oil based recipes to see how those work. One thing is for sure, char pigments are to dye for! 😉