I've been using Mont Mater artist brushes made from ultra-fine "taklon"
fibre to get a very smooth finish on small pieces. I'd like to buy some
larger taklon brushes but I can't seem to find enough technical detail.

Can anyone share their experience with taklon brushes, comparing
with other high quality brush types?

The Mont Mater website doesn't state the fibre diameter for the 25mm
brushes I've got, and it's not clear whether the larger 50mm and 75mm
brushes are the same or coarser. Wikipedia says:

Quote Originally Posted by Wikipedia
Taklon is made in several sizes, ranging from 0.08mm to .15mm,
which mimic hair, to .20mm, which mimics boar bristle.
What's the fibre diameter of sable and badger brushes?

Also, is it safe to use taklon for all solvents? It seems fine with
ordinary oil-based paints, but I'm wondering whether it's ok for
polyurethanes, etc?

Cheers.