Golden "heavy body" acrylics on gessoed linen canvas, 12" x 18".
here is the acrylic version. the main difference is in the depth of color on the couch. i satisfied myself that i could match it in the watercolor painting (below) with additional layers of paint, but decided not to put in the effort.
now to summarize the differences between watercolor and acrylic that most impressed me during the paired paintings. (disclosure: i developed as a painter by optimizing my setup and process around watercolors, and this shapes my working preferences.)
paint dryout - watercolors in pans or palette wells are wetted or left to dry: they conveniently manage themselves either way. i asked several acrylic painters for advice and they all said acrylics have to be diluted or mixed with acrylic medium or water to retard drying time. i found they harden in about 20 minutes, have to be put on the painting or cleaned off tools and brushes before they harden, and this time limited task of managing paint before it dries was a painting distraction.
paint waste - for all the watercolor paints i habitually rely on, i empty tube paints into small porcelain condiment dishes, where the paint dries out to make large pan watercolors (basically the same format as you can buy, at much higher cost, from blockx or winsor & newton). these pans can be wetted and dried an unlimited number of times; the only wasted paint is in the brush rinse water. acrylic seems more wasteful. in my practice a lot of acrylic paint got blotted onto paper towels, or formed a mixture residue on the disposable palette that had hardened before i could use it. mixing colors or blending paint with acrylic medium forced paint up onto the brush ferrule, where it had to be scraped or wiped off. more thick paint goes into the rinse water each time the brushes are cleaned.
paint consistency - i found the thick acrylic paint consistency to be unpleasant. no matter which dilution i tried, the acrylic could not be applied without brushmarks. i could not create smooth color areas ("washes") without applying the paint in a thick, hiding layer. diluted paint applied as a "wash" tended to creep back and dry into a smaller, clearly bordered puddle of evenly distributed color.
chroma & value - watercolors seem to start out dull and light valued, though they can be built up to acrylic appearance by repeated glazes. acrylics start out saturated and strongly contrasted, and have to be methodically dulled down by glazing with black, white or complementary hues. i came to the conclusion, surprisingly enough, that it was easier to make a watercolor look like an acrylic than to make an acrylic look like a watercolor. acrylics produced more vibrant effects of color and contrast, while watercolors produced more delicate effects of atmosphere and light.
wet in wet - i was unable to produce wet in wet variety in acrylics, unlike the fantastically varied diffusion and backrun effects you can get in watercolor. dropping paint into a watery puddle, or puddle into a diluted paint mixture, produced a dried color that was smooth and had well defined edges. backruns and diffusion just didn't happen in acrylics. all contrasts were in the brushstroke textures.
tinting strength - the relative tinting strength of pigments is different in watercolors and acrylics. this did not seem to be only a property of the pigment load in the paints, but also the way the pigment combined with the vehicle as the resin dried. in my palette i greatly underestimated the tinting strength of acrylic nickel azo yellow and phthalo green; quinacridone magenta was weaker in acrylic than in watercolor.
drying shifts - in general drying shifts in value (the color appears lighter after it has dried) were larger and often harder to anticipate in watercolor than in acrylic. however i found that novel *hue shifts* in paint mixtures occurred in acrylic paints, as if the tinting strength of the pigments changed as the paint dried. for example, a mixture of yellow, magenta and white appeared a perfect flesh pink on the palette and when brushed out, but dried into a definite yellow.
support - the support texture shows through much clearer in acrylic, although the texture is a generic weave; the paper textures in watercolor have a much greater variety and more impact on paint appearance. the absorbency of papers contributes a lot of variation to watercolor painting, but the lack of absorbency in gesso is constant; gesso also contributes to the brighter color in acrylic. paper creates a softer, more atmospheric color in watercolor or in acrylic on paper.
underdrawing - the underdrawings in watercolor pencil lifted equally easily from both the gessoed canvas and the sized paper, but the underdrawing in carbon pencil held much better on the gesso. in watercolor it lifted to muddy the color somewhat, and i had to redo the drawing before the painting was finished.
glazing - i have a lot to learn about building alternating layers of paint and transparent medium, in acrylic, but overall i think that similar glazing adjustments were possible in both media. acrylic also offers a wider range of surface finishes -- gloss, matte, dull, textured, etc. -- compared to traditional watercolor. (i have not tried coating a finished watercolor with acrylic medium.)
pigment texture - pigment textures, including flocculation and granulation, are effaced by the acrylic medium. every color has the pigment texture of house paint.
brush blotting - if i need to dry a watercolor brush as i paint, i simply wipe it across the leg of my denim pants, or snap out the excess water onto the floor. both stains clean up easily. i can't do either with acrylic; i need a rag or paper towel. and once a paper towel has two or three wipes of acrylic on it i must throw it away to prevent unwanted paint transfer when i use the towel to blot paint from the painting. my trash can quickly filled with paper towels.
i am enthusiastic about continuing with acrylics -- at least, until i use up the paints i've bought -- but i realize i have to rethink my technique from the medium up. you can't just dip a watercolor brush into acrylic paint, and expect to fly from the beginning.