What is Flow Improver?
The Amazon description sort of speaks for itself:
This medium increases the flow of acrylic colours, allowing the application of areas of flat, even colour without changing colour strength. It is also effective for hard edge painting techniques. It maintains the stability of the colour and slightly slows drying
Accessed August 2020
From what I understand flow improver decreases the surface tension, so when added to acrylic paint and water it means that the paint has a better flow.
How do you Use It?
You can either add it to the water you are using or directly to the paint and mix on the palette... I would for example add it directly if the environment is very hot or windy. This article is painting like a watercolour so I add it to the water as we will be using lots of water.
A third way of using it is described in the partner blog 'Use Acrylic like an Oil'. I explain how to mix the flow improver with another medium to make the paint act very differently!
Flow Aid is an additive so care must be taken to avoid adding more than 30% to acrylic paint either neat or mixed with water.
What do you mean by an Additive?
Acrylic gels and mediums are acrylic based. Meaning that they have the same polymer binders that the paint does. The difference between them and paint is that they do not contain the pigment and each one has been designed to perform a particular function.
Anything that you add to acrylic paint / medium / gel without this binder in is classed as an additive. Hence water is an additive, sawdust is an additive etc...
Golden Rule: do not add more than 30% of any additive (or 30% of combined additives) to acrylic paint / gel / medium. If you do not follow this rule the binder could break down causing cracking or flaking.
How can I tell which are additives and which are mediums?
If they are a gel or medium it will state that in the title e.g. 'glazing medium', 'gloss gel' if they don't they are an additive... Alternatively look on the back of the bottles, there are always instructions.
I have Flow Aid is this the Same as Flow Improver?
Yes.. different brands call it different names.
So... how do I use Flow Improver to make Acrylic act like a Watercolour?
Firstly, get some watercolour paper... if you want acrylic to act like a watercolour do it on the correct surface.
Secondly, don't make your life hard by using heavy body acrylic, its designed to be thick. Use a soft body or flow acrylic. Acrylic Ink is a great option too.
When you use acrylic on watercolour paper you can relax the 30/70 'golden rule' and use more water. This is because the extra absorbency of the paper (as compared to canvas) creates a surface that is easier to bind to.
However, water on its own does not reduce the surface tension enough to give it that 'watercolour feel'.
So finally add the flow improver to the water that you are mixing with the acrylic. Then add plenty of water / flow improver to your paint, as you would if your paint was a watercolour. Create a mix, even washes, that is fluid like a milk consistency.
Acrylic will never be exactly the same as watercolour, it retains its colour on drying and does not lift once dry but it does work well, even with wet-in-wet techniques.
Try it!
P.S. you can use flow improver in this way with actual watercolour paint, this reduces the hard edges... great when painting portraits when trying to avoid hard edges on the skin.
Next Blog is a Partner to this one: How to use Flow Improver + Slo-Drying Medium to make Acrylic Act like an Oil!