Artgerm Loaded palette knife

Hello everyone hope everybody is doing fine :)

So what I would like to ask is if any of you know how to make the loaded palette knife to paint flat?

To be more precise, I'm trying to reproduce the loaded palette knife of an Artist named Stanley Lau (Artgerm), and while looking at some of his videos I see that his palette knife is not showing the bristles. but I haven't been able to remove those bristles from brush. I hope somebody can answer this topic. If you want any reference on Artgerm's work please check his youtube channel