I've been intrigued with the idea that paint is paint and the only thing that distinguishes oils from acrylics is the medium. They have different drying times, true, but with oil paint drying time can be adjusted by additives such as cobalt dryer. I paint rapidly, wet into wet, so I felt that switching to acrylics wouldn't be that difficult.
As an experiment I stretched a 36" x 36" canvas and gessoed it. I then drew a grid with lines every 6 inches. I transferred my drawing and begin glazing in my underpainting. I painted for about six hours carefully glazing and scumbling until I achieved the desired effect–a very thin but accurate rendition of my reference. I didn't worry about surface texture or virtuoso brushstrokes. I worried only about painting values and hues.
I then wet my canvas by spraying on a thin layer of water from a hand-pumped atomizer. I then mixed up a series of values and hues carefully using my nine value grayscale to carefully match value. I mixed my colors with my left hand and swiped my brush across my palette knife to load my brush with broken color. I then very quickly applied the paint into small, discrete areas. This breaking up the painting into small areas was the major difference from painting in oils. With my initial layer I did occasionally notice a border between the different areas. But on the second application of paint these borders were eradicated and I could see no transitions.
I was surprised at how similar painting with acrylics is to painting with oils. Since my initial foray into painting with acrylics to get an oil effect I have discovered that adding Extra Heavy Molding Paste from Golden Colors helps give an even more oil-like application of paint. The reason is the paste gives an oil like feel as acrylic can seem watery, with too much give to the paint, and the paste makes the stroke dry as thick dimensionally as oils. Acrylics dry by evaporation so that when dry the textured stroke will be thinner and not have the extreme texture as how it looked when applied wet.
Some ask why anyone would want to make acrylics seem like oils. If a painter likes the appearance of oils so much just use oils, right? This is true as long as you don't want to explore the extremes of thick paint. Oils has a limit to how textured you can get and still preserve a stable paint film. IN some of my oil abstracts I built up the paint fils so thick that it began to form a weird alligator-like skin as it dried. It wasn't a pleasing effect and I also felt that the film could delaminate at a future date. So I abandoned the extremely thick oils (over 1/4" thick) and started using acrylics for these extreme effects. I have had no problems with acrylics and found them to have nearly unlimited texturing ability. You can almost use the paint like a sculpting medium if you so desire.