The best thing about duo-fiber brushes (aka skunk brushes) is that they're great multi-taskers and can be used in various ways for different products. They are made with both natural hair (the shorter black ones) and synthetics (obviously, the longer white part), so they work well with liquid, cream and powder formulas. The shape allows for stippling liquid foundation and tinted moisturizers, but it's also ideal for picking up just the right amount of bronzers and very pigmented blushes. It's usually recommended to use a skunk brush with blushes that might be too dark or streaky for a light and natural application.
I own several duo-fibre stippling brushes, including one from Guerlain (which I think works better with powder products, so it's less of a stippler). My favorite one for the last year or so has been this Sephora Professionnel Platinum Stippling Brush #44. I find it to have the perfect density, softness, length (hair and handle). It's as efficient with my various foundations as it is with blushes (including cream) and bronzers. Generally speaking, I'm really impressed with Sephora Professional Platinum series. There are very few duds in this line of brushes and they're great value.
The #44 brush doesn't require any special technique and I reach for it without much thinking or planning. The brush is there, it performs well and takes away the guessing. It's also quite soft, so I don't experience any skin freakouts and well made, so no shedding, even in my older one that's been washed countless times. I keep one of these Sephora brushes with my foundations and another one in the blush drawer, so you understand it's become a staple.
Sephora Professionnel Platinum Stippling Brush #44 ($35) is available online and in store.
All photos by me (with the help of Sophie).