If the screen is at least 2mm up to 3.5mm. IMO, I wouldn't use anything that passes through a 2mm screen, and At the VERY MOST I wouldn't use anything retained on a 4mm screen for Turface and grit. The bark can be a bit larger (1/4 inch.)

Not sure how to measure the holes. Maybe if you had some known sized wire (say, 2mm Bonsai wire?)

Rob

Hey, again. I went to Callahan's and had them cut 2x2ft of various size screens. I stapled the screens to a very basic sifter that I built. That might be the easiest route.

A simple kitchen strainer will work fine.. You just want to get the dust particles out.

Laura

I'm sorry, let me clarify my comment. I predominantly use the GM for Bonsai and other plant's that require sharp drainage. It has been recommended to use what is retained on insect screen, however that is a bit small for my purposes unless I am going for more water retention (because I do save the screened leftovers).

Rob