Many painters paint with lots of paint, a heavily loaded brush. I don’t typically paint that way. I like more control for how much paint is applied at a time. And I often paint in translucent layers.
However when painting Plein Air, outside landscapes which are time limited – due to the sun moving across the sky. I paint faster and tend have more paint on my brush and try to not fuss with where I decide to place it so there is a more fresh appearance to the marks and strokes. Plein Air painting demands immediate decisiveness.
I also tend to get different color changes happening in single brush strokes loaded with bits of different colors on the brush at the same time, allowing them to mix slightly while on the canvas. This technique in particular, makes paintings magical and exciting to my eye. I do not "mix" as in stir the paint to blend it while the colors stream out of my brush. I let the brush marks be as they happen.
For this reason, even though I will mix colors on a pallet or container, I rarely ever mix a large batch of the same color paint. I tend to mix a few brush strokes worth of paint at a time if I am after a particular color. I do not see the world in flat sections of color so I paint in variations and blends. And I prefer the varied versions of color that flow out of a brush while painting.
However when painting a large smooth sky on a mural, it does help to have sizable batches of particular colors to cover large areas and have on hand for further touching up. And even then, that sky color is going to change from top to bottom; from a darker more red tone, purplish deep blue, high in the sky, to a faded light turquoise beige at the horizon.
I am not drawn to even flat unchanging colors, typically known as "graphic" blocks of flat unchanging color, such as in old poster art where printers had to make a whole new plate for each color and minimized the color options to keep the process simpler and the cost down. I love the antique poster prints, because they had a lot of layering. Yet posters later on. got simpler not more complex. Painters are not limited to certain colors and we can mix colors to please our eyes as we see fit, so that is what I enjoy in painting. Seeing the painter's choices by seeing the brush strokes and the colors that happen more spontaneously.
While painting, I load a brush, 1/3 – 2/3’s full of paint. It optimizes the capillary action that urges the paint to leave the brush. I try to keep paint from building up and drying at the top end of the bristles where it is secured to the brush handle.
There is a fine balance between manipulating the paint on the brush as it is put down, and moving, altering, or mixing with the paint on the painting. I often dab the brush on the pallet before I put it on a painting. This allows me to first check the flow (moisture and color), and second to remove some paint first in order to manage not putting on too much paint down at a time nor to have the liquid be in excess. I also dab, to adjust where the paint is on the brush. I want the paint near the point end of the bristles when I want to lay it on the painting. I want it further up the bristles if I am blending and do not want the full load to arrive on the painting all at once., especially if I want to manipulate what is already on the canvas before I let the paint on the brush join the paint on the painting.
I rinse the brush as needed to change colors, get rid of muddy colors, or to freshen up the moisture inside the bristles to keep the bristles pliable. Drying paint will limit the flexibility or movement of the brush. I frequently rinse a brush well, and dry off excess water (or solvent) before collecting more paint.
Due to capillary action, if a brush is too dry it will pull up paint or moisture off a painting into the brush, which is something to know about so you can use that when you want to, and don't have it happen when you do not want that effect. And it is good to know how to lift something if you want to remove paint or moisture.
While painting in acrylic paints, I use a clear matte or satin medium for blending. It takes very little pigment to add color to a painting. And having a medium to extend the pigment versus water helps the paint bind well, and the paint with less pigment will remain the same consistency as paint versus becoming much too watery or thinned and runny.