About a month ago, when I was becoming more interested in gouache paint, I was introduced to the fact that acrylic gouache was a thing. What is gouache? On a basic level, it's watercolour paint with extra pigment and an additive - often chalk - that increases the opacity and flatness of the paint colour. These qualities have historically been useful in graphic and poster design (to the point that gouache is often known as poster colour too), and they happen to be useful to miniature painters too.
The problem for mini painters is that gouache shares watercolour's binder - gum arabic - which has a propensity to re-wet and dissolve, when water is reintroduced after drying. This would make many of the usual layering and washing mini techniques a little problematic.
Acrylic paint doesn't have this problem - it polymerises after water evaporates from it, creating a waterproof film that can easily be worked over. But as many of us know from acrylic miniature paint ranges, some colours can be poorly pigmented or otherwise turn out quite thin and transparent. From what I've read of acrylic gouache, it shouldn't have this problem, seeming to be an acrylic paint (quick drying, waterproof) with added qualities of gouache. (highly pigmented, opaque, matt) Now, I know acrylic paints with these properties aren't unknown to hobbyists! We could all probably recite two or three examples of the top of our heads. But with the larger quantity per unit and/or lower prices of acrylic gouache, I wondered if they could also have a place on the mini painter's palette.
My first inkling of acrylic gouache's existence came from a Jackson's Art Supplies catalogue, so I visited their website and perused the brands they stocked: they were Vallejo acrylic gouache and Turner acryl gouache. The former seemed to be a liquid paint, or at least liquid enough to put in 35ml dropper bottles (typical Vallejo!) and that turned out to be the case. The latter is a 20ml tube paint, which mini painters often have trouble with as it is usually fairly thick in comparison to mini paints, and thinning to a useful viscosity for mini painting usually thins the pigment right down as well. But I was confident that the extra opacity of this paint could stand up to a little thinning, so decided to buy a couple of tubes of that too.
But as above: what colours? I didn't want to buy a whole palette of paints that I might not like (and especially not with a Paintier 80 already groaning with pots), so I'd only test a few. Say, four or so. The first two choices were easy - given acrylic gouache's potential as opaque basecoats, I went for the two colours that are usually poorly pigmented in hobby ranges: red and yellow. Specifically, Turner permanent red and Vallejo primary yellow. The other two were colours I'm usually fond of: ochre and light grey, or Vallejo yellow ochre light and Turner neutral grey 8. When they arrived, I matched them as well I could with other opaque paints I already have. The matches aren't exactly close, but as the purpose of this test is opacity of acrylic gouache vs. mini paints, it perhaps doesn't matter so much.
AKA 'the bit you're here for'. I grabbed some plastic models, two of each type for each colour of paint tested, and gave them a coat of black gesso where needed. With that dry, I shook and stirred the test paints (the ones thin enough to shake and stir) and painted one thinned layer each, followed by a second layer of the same paint. Here we go...
Vallejo acrylic gouache primary yellow vs. Miniature Paints mustard, part of the range owned by Ral Partha Europe. I've found it to be a pretty good opaque yellow, though more as a basecoat for bright yellows. These were compared on termagants. The first layer:
I've got to admit, I'm pretty disappointed with the Vallejo colour. The mustard obviously doesn't cover on the first pass either, but isn't quite as transparent and patchy as the primary yellow. The second layer:
Two layers of primary yellow doesn't look too much better than one. By comparison, the mustard needs a couple of touch-ups here and there, but has created a pretty solid base.
I wonder if, as a more 'earthy', ochre pigment, mustard has a slight advantage over primary yellow. Either way, it's pretty obviously a failure for the Vallejo colour. It is the only yellow in the range without an opaque cadmium pigment (most of the extensive yellows and reds seem to have actual cadmiums rather than imitation 'hues'), and I wonder if one of the others would have more opacity. Although lack of cadmium is the reason I chose primary yellow, and given that this is a hobby full of brush-lickers and people who set their mugs of coffee beside their brush-washing jars, I wouldn't feel responsible in recommending them!
Turner acryl gouache permanent red vs. Miniature Paints deep red. The latter made my throw out my pot of Citadel foundation mechanicus red. Like that OOP color, it's a nice... well... deep red with good coverage. Permanent red is obviously brighter and more saturated. First layer on skaven clanrats:
The deep red does it's thing with no complaints, but wow. The Turner paint made my jaw drop as I saw just how intense, let alone opaque, a single thinned layer of this red was over black primer. Any misgivings about the medium from the Vallejo primary yellow test were blown away. There was quite a colour shift as it dried, turning paler and almost pinkish (not to mention quite matt) compared to the wet paint, which makes me suspect this has a bit more filler than the Vallejo paint. It reminds me a little of the short-lived Rackham paints in that regard. But as you can see in the photo, the dry paint is still very bright and vibrant. Heck, my camera couldn't even cope, washing out the painted area! For the second layer photo I turned the camera brightness down a bit:
Vallejo acrylic gouache yellow ochre light (say that ten times, quickly) vs. the old Citadel foundation iyanden darksun. Probably the closest colour match in this test. Two kroot were the volunteers here:
Both seem to have a similar level of coverage. Although, I don't know if I've been soured by the primary yellow test, or if unlike other models in this test, kroot are made of a lot of gangly angles rather than flat surfaces, but the citadel colour seemed a little easier to brush on. Second layer (only on the upper halves, if you please):
A similar opinion to the first layer. I'd say iyanden darksun might have the edge, but in the greater scheme of things it's a negligible difference, and well offset by the price point too. (Note: my camera and screen seem to make the yellow ochre light seem more bright, saturated yellow than it really is. I can't seem to fix the problem without throwing it off even further.)
Turner acryl gouache neutral grey 8 vs. Citadel celestra grey. Tested on two space marines (sans bolters):
I should've tested this against ceramite white! The colour tab on the tube, and the actual paint on a white palette, are obviously grey; but painted onto a black-primed model it seems like bright white (even without the glare in the photos). Like the permanent red, it provides a quite opaque first layer, even when thinned down beyond what would be considered wise. Indeed, that thinning might be necessary, because I got another hint of chalk filler before I did so: looking closely, it left what might charitably be called a 'fine tooth'. On the second layer:
Again, excellent coverage. The fine grittiness and brushmarks weren't apparent this time, but there's still a little bit of 'thick' texture left on the surface. While the problem wasn't apparent with the permanent red, the celestra grey left a similar kind of texture on the other marine, and I have had this kind of trouble with white paint before. Am I still not thinning it enough? (I think the opacity could still take it) Am I loading the brush too much? Either way I'd say the Turner colour just needs just a little more care for fussy painters (self included), and maybe a drop of flow-aid.
Vallejo acrylic gouache, being similar to their mini paints, has about the same level of durability. A good rub with a fingertip doesn't damage the layer too much. The extra filler of Turner acryl gouache causes minor hiccups, though. Unusually for a product labelled 'acrylic polymer emulsion', it seems to re-wet to some degree - the permanent red stained the water on the brush, though without damaging the paint surface, and the black primer started to show through the neutral grey. Although it has to be said this involved a lot of water and purposeful scrubbing. I was able to layer and shade with water-thinned paint, washes and inks without any problems.
Turner acryl gouache also seems to rub off a little more easily too. I admit I was quite disappointed to discover this, but as with the Vallejo paint this was after a good rub with a fingertip. It may be that the paint needs a little longer to fully cure. Also, even the level of protection afforded by a quick layer of GW wash seemed to help matters. I think a proper, normal varnish might cut out most of that problem.
The conclusion may be a little... inconclusive, in terms of the aim to find out if the basic medium of acrylic gouache can provide suitable opaque basecoats for minis. Vallejo primary yellow might be the blip in this test but it's enough to cast some doubt on other colours in the range. (After using these, I wonder if there's much difference in formulation between Vallejo's acrylic gouache and their model/game color lines) On the flipside, I could be confident that Turner's range would be reliably opaque, but would the apparent weakness of the dried layer negate that advantage, and would the (quite minor) chalky problems of the grey affect many others? I don't really think so, for reasons mentioned.
It seems that the properties and opacity of acrylic gouache paints vary across brand names and colours, just as they do with miniature paints. With that in mind I think I could happily recommend acrylic gouache in general as miniature paint, with extra opacity bonuses and maybe a tad more focus on sealers. The hope I had before the test was justified too: with comparable (or fixable) quality to mini paints, the price of acrylic gouache is fairly appealing. (Jackson's normally sells those Vallejo 35ml bottles and Turner 20ml tubes for less than GW sells a 12ml pot, and they're having a sale on Vallejo acrylic gouache at time of writing too.)
The stronger, more specific conclusion, that I didn't actually expect? If you want to paint very bright red on a lot of minis in a short time, get some Turner acryl gouache permanent red now.