Not tryng to give lessons or tell anyone what to do or counter to anyone here. This is just some thinking from several points of view:
1. Ecology-wise, synthetic bristles add to plastic pollution after they are thrown away, same for any synthetic handle.
Wood handles add to tree harvesting.
Metal handles add to pollution by mining and metal acquiring processes.
So:
Plastic made out of HEMP would be a good sollution for both bristles and handles.
2. Animal cruelty-wise, horse bristles are the most ethical, since the mane and tail are groomed and trimmed regularly.
Everything else will bother SOMEONE, in some way.
Personally, i have a total of 4 brushes, 2x boar, a synthetic and a badger. I consider adding a 4th or 5th gen. synth to that in the long run, but i simply don't need more than that.
Each to his own, but realistically, the best solution for the biggest part of the problem is pure and simple MODESTY. No more, no less.
Find what works for you and USE IT. Untill it really needs replacement. There is no real need to buy something new just on a whim or because it looks good. Plain and simple.
I take great umbridge in your statement that wooden handles add to tree harvesting. What utter tosh! Most of the handles I’ve carved are from rescued, reclaimed and otherwise cast aside bits of wood. Besides, trees can and have been harvested with ecological benefits for centuries. Coppicing, pollarding and thinning of responsibly managed woodland has actually been proven to increase biodiversity.
However, I heartily agree that the felling of exotic species purely for their wood and with no plan to replant or care for their surrounding environment is at best wanton stupidity and at worst a grievous crime.
My very first wooden handle came from a large limb of ash that was pruned in order to allow easier passage of the 2012 Olympic procession - the tree lives yet.
Ash dieback disease is rife throughout this country and has decimated many of Europe’s
fraxinus species. Are we to just let ALL of the wood rot? Burnt it all? Or should we put some to good use?
Trees can be farmed for the good of all but governments and companies around the world lack the foresight and planning to start a proper cycle of anything other than fast growing, near-useless spruce planting in this country. The quick buck, the instant return condemns us all.
Find me another handle material that is as sustainable, as easily worked, as practical and as beautiful as wood. There isn’t one and never will be. You may play with your 3D printed corn starch shite but I’ll stick to mother nature’s best and praise her for it. All hail wooden wood off trees!
For me, as a confirmed meat eater, the most ecological shaving brush is one made of wood without the use of electricity in its making, a natural coating and a boar hair knot. I’ve yet to find a horse hair knot than can come halfway close. Except for the knot plug, all of this may at least one day rot back into the environment from whence it came and enrich, not poison it.
Point made? I ruddy well hope so!