couldn’t get my hands on any hay or straw for a period of time so I ended up trying rolls of burlap used for wrapping shrubs in the fall to protect them from winter winds/cold.
I used 2, 3x25f rolls of burlap to fill the 45gallon barrel i use as a filter. seems to work quite good. I find it alot easier to change out than hay also I can ensure that the filter material is tight against the sides of the barrel. I tried the hay in the bag trick but had issues of the gas bypassing the main mass of the filter and flowing up around the edges where resistance was least.
this may be a good alternative for those city dwellers that don’t have access to agricultural goods or need some filter material in a pinch, you can get this stuff year round a home building centres.
Been using the same burlap for roughly a year now and holding up well. has just been turned black from the soot but no signs of degradation of the fabric and remains quite “free flowing” due to the large pores that are manufactured into the material. haven’t tried to wash it yet but black soot comes off when touching the burlap so assume that this is also a likely possibility as well.
Biggest downfall with this material is it freezes up in the winter, however hay and all other materials due this. The warm woodgas will heat things and melt the ice in the filter however this does take a bite to do and depends on the ambient temperature so I find that when we get into 0 Fahrenheit I run without any filter material except for some courser metal screens or there is too much restriction from the filter (due to ice bulidup) and I have idle problems.
the other option would be bypassing cooling rails to dump warmer air into the hay filter thereby warming the filter material faster. This may be one of my projects for summer
running without a large filter mass does give more soot up to the throttle body however this can be cleaned in the spring/summer and is payment for having a consistent idle no matter what temperature or how long the gasifer has been driven.
my 2 cents