Sifting the sawdust helps get it more to the consistency of wood flour.

Beware of any contaminates that may be lurking in your orbital sander dust from other projects. Example: Very tiny bits of red enamel dust can turn your mix red while it is setting up. Discoloration happened in 'fills' on my first boat. Red spots did not occur/show until the mix started to dry.

Lew

I tried to make my own wood flour with sawdust from my random orbital sander. I was hoping I could make wood flour that would be the exact same color as okoume. The consistancy seemed OK, but the color was much darker, so I decided not to use it. I don't think I had problems with contaminates because the sander has only been used to sand okoume.

Mark

I collected more than a quart of wood flour from the vacuum bag on my RO sander when I sanded out the deck of my hybrid. I will second the comment about contaminants, though. Make sure your bag is clean before you begin. -Wes

I've used wood flour from sanding Okoume with my RO and when mixed for fillets it's nearly a chocolate brown color, much darker than than the peanut butter color from mixing the purchased wood flour. I filleted my cockpit with it and I love it. It seemed just a tad bit coarser as well.

You can make your own wood flour.  Keep it clean and make it from a lighter colored wood, I use sassafras to get a light color, if I want it darker I add a little darker sanding dust, mix it then add epoxy.  Try adding More or less until you get a nice color.  It does to darken upon drying.  With practice you can get any wood color.

I've mixed sawdust from my HEPA filter in the shop vac and other sources and sieve it for contaminents. I'll usually mix it half dust and half silica to lighten it up. But I'll usually only use these mixes where they won't be showing, just in case.  You could probably use cookie crumbs if you can get them fine enough.