Someone asked me a question about my painting style, and when I realized I had already written a book - I decided it was probably a good idea to just make a journal post about the topic. That way others may be able to find it useful as well.
Here's the question: "how do you get your acrylics to look so smooth? Do you water them down or is it the brushes?"
That's a loaded question! I have always been into the idea of painting that way - I believe it's technically called a blended style - but I was doing it before I even heard about that! Basically it's a combination of paint, brushes, and ocd. xD At one point, I decided that I didn't like the way lines and such that hadn't been blended in looked. I found I had a lot of trouble blending though with my current brushes/paint, and considered trying oils. I followed the suggestions of an oil painter who offered lessons and info on what brushes to get. The oil painting didn't work out, as I had just become too accustomed to acrylics, but 2 of the brushes ended up being incredibly useful for acrylic painting.
The funny thing is, I have never heard of people using these brushes with acrylics and you can't even buy them on dickblick.com. You have to spend like 24 bucks for one brush through a private supplier, but on the bright side the brush lasts 2+ years (mine is still going strong). Seriously even with acrylics that tend to eat the heck out of any brush. It's a brush by Alexander and it's a badger filbert. It only comes in one size. They also make a badger flat brush that i use for background work. But, I use the filbert brush for just about everything - the only time I don't use it is when the space is too small for that brush to get into and in that case I use a small titanium round. Titanium is synthetic and holds up amazingly well to acrylics. It also has a tendency to get very frayed once worn in and this is great for blending.
See a picture of these brushes here and notice the difference between a worn in brush versus a new one- sta.sh/0vdqqmxpl44
That's the other important thing to note. Most brushes are pretty useless for blending when you first purchase them because they are too stiff and still have too much form. It's a good idea to use the brushes for other things until they are properly worn in. I use the rounds for detail work until they get frayed enough to blend with. I also keep my main brushes in water all of the time. The rounds don't take as well to this as the filbert and flat does, but they only cost 2 dollars a brush - so I don't really care. So long as you wipe them and change the water once a day, you will not have to worry about any funk on the brushes. This helps to keep them soft..another aid in blending.
Lastly, the paint. I use 3 different types of acrylic paint: Golden Heavy Body, Golden Open Acrylics, and Chroma Atelier Interactives. See picture here: sta.sh/024ga3y28c2o
Open Acrylics are amazing for blending. As with all acrylics you have to keep them wet. I use a fine mister from Chroma Atelier to keep my palettes wet. Spray them every time you notice them starting to get tacky. With Opens all you need to blend right is a bit of water. Mix it in as you're using it on the palette. You want the consistency to be creamy but not watery. This is something you will have to just practice - maybe I'll make a video sometime in the future to show what I mean, but otherwise it's hard to explain past creamy! Do not keep it thick though..that will just make a mess. Don't let it get too watery or the pigment won't hold. You can always tell when they paint is perfectly mixed when it just flows smoothly and mixes well with other paints already on the canvas.
Heavy Body acrylics are what you use when you can't find what you want in opens. I use them for all of my neutral gray paintings because sadly, they're not available in opens. I use retarder to keep them from drying so fast and keep them wet more often than I have to with opens. The paint is very thick and will have to be watered down a bit more to make it workable. It is great paint though..it usually comes out so nice and creamy when watered down right, and the pigment is very strong.
Interactives are a nice alternative to the more expensive Golden products and I use them for blocking in huge sections of color. Usually for backgrounds and landscapes. In my personal opinion, they dry too fast for portrait work. Typically when working on a portrait you want a palette to be able to stay wet for days. Even in an airtight container, this paint likes to dry out. The other big reason I don't use it is the severe loss of pigment. They don't seem to be bound as well as the Goldens pigments and when the amount of water I like to add is added, the paint loses it's oomph. Especially if working on something with a liner brush where the mixture needs to be very fluid or glazes.
The rest is just finesse which comes from practicing..and practicing..and practicing.
I hope that answered you're question though and that I didn't speak too confusingly. It's sometimes hard to explain something that you just know from doing it over and over and I might have left something obvious out!