Painting wood beside acrylic white paint - brown specs? I'm painting a bunch of different wooden frames white and the only...

I'm painting a bunch of different wooden frames white and the only paint i own is acrylic craft paint, when doing this though some of the frames started having some brown specs showing up over top of what i just paint, almost close to i had sprayed some brown paint on it, what should i do, and why did that happen?
I enjoy a sound out more or less...
Answers:    It sounds to me approaching you skipped the most important step--priming the frames.

Anytime you're painting something that already have a paint or other finish on it, or if you're working with raw wood, it MUST commence by applying a primer first. My favorite brand is Kilz. This will allow your paint to adhere properly.

The other issue is that you're using craft paint. This type of paint, when used on a large surface, does not move out a very attractive finish. You would end up next to a much more attractive frame if you purchase spray paint, which goes on evenly.