I heap abuse on synthetic brushes. But some synthetics are not too bad–for oils. I haven’t found any synthetics that can replace sables for watercolor painting. Not even close.
These synthetic rounds from Winsor and Newton are OK. Monarch brushes are made from “synthetic mongoose fibers,” whatever that might be. Winsor Newton claims that they are more durable than natural mongoose, which in my experience is accurate.
They handle OK as well. They are too stiff for fine or close work but for broad work, they handle as well as my high-end bristle rounds from Isabey. Actually, they might handle a little better.
For medium to large passages, these brushes are serviceable. What is medium size? The 3 brushes in the photo are 10s, which is certainly medium. In general, medium starts at size 6.
Is the performance upgrade enough to change from natural bristles? When the Monarchs’ prices are significantly lower than the bristles, the Monarchs are an easy choice. When the prices are similar, the choice is not so clear.
On Blick, size 8 Monarchs are $12.68; the comparable Isabey is $12.88. The size 12s are $17.13 for W&N, and $23.66 for Isabey. (No Isabey 10s are listed.) If I was buying a 12, I would unhesitatingly choose the Monarch.
Here’s a painting that is seeing a lot of Monarch brushwork.
You can see from my palette that I mix tones as I need them. The only premade colors I use these days are 3 values of gray and 3 values of burnt sienna. The premade colors provide me with a color-mixing headstart. I used to prepare more tones but these colors provide enough of a boost that I don’t need any others.