Underpainting is 50/50 Gesso and acrylic paint, one layer.
I did both of these paintings right after being outside sketching in the woods. So these paintings are memory paintings. I did the oil painting first, and with the acrylic painting I tried to keep the brushstrokes and colour palette similar to the oil painting, so it is easier to compare.
Same coarse air brushes used in both paintings.
The oil paint is 3:1 oil paint and Liquin medium – for more transparency and faster drying time.
Acrylic paint is 3:1 acrylic paint and gloss medium – for more transparency, gloss and flow. Not sure how this affects the drying time.
Differences
Drying Time
Oil paints still wet when painting finished, so could only work wet-on-wet unless you left the painting for a number of hours.
Acrylics dried extremely fast in comparison – with brushstrokes drying in minutes so mostly dry-on-wet was the way to work.
Colours
I already have a larger variety of colours in oils than I do in acrylics, so I have more colour options without having to buy more paint.
Colours are much more intense and vibrate against the dark background much more than the acrylic paint.
Oil paints have more subtle colours.
Transparency
Oil paints have a much more radiant transparency and would have more interesting layers when applied dry-on-wet. (But drying time makes this an issue to do fast).
Acrylics have good transparency with the gloss medium (and have the big advantage of drying in minutes). Radiance when layering semi-transparent paint not as good.
Similarities
Brushstrokes
Brushes carry paint slightly smoother and longer with oils, but not much difference, especially with more gloss medium added to acrylics.
Overall
Oil paints have more possibility for colour work, but the process would be much slower, and would have to be done in stages if I wanted to layer dry-on-wet. Also cannot paint in oils in sketchbook!
Acrylics better for fast studies and when I want to layer dry-on-wet in one sitting.
Oils better for bigger pieces, that I don’t mind painting in stages.
Georgina Harris 