I love using washes. Nearly every army I paint involves a black or brown wash. In the interest of saving a truckload of cash on these bottles of wash, I tried making my own using varnishes, soaps, and acrylic medium but they all acted a bit funny – and nothing like the GW washes. In the end, I bought a couple of bottles of Vallejo washes($8 on Amazon), but I was still trying to experiment, so I also grabbed a bottle of flow aid.
This is a transparent medium similar to GW’s Lahmian Medium except it has some extra magic that breaks the surface tension and allows the paint to flow much easier. Surface tension [Wikipedia] is the physical attribute of liquids to cling to things rather than flowing freely.
When using a wash, the surface tension of the acrylic paint – along with its thickness – keeps it in a little droplet of pooled paint. Releasing the surface tension will allow it to release and flow about – what you are usually looking for in the shade.
I have found two great uses for the flow aid medium so far:
The first is to make washes on a much larger scale using tubes of basic acrylic paint you can get at a paint store. I used these to paint my Pegasus Buildings – something that would have taken about 20 bottles of Earthshade to complete.
The second use for the flow aid is to improve the flow of current washes if you want it in the recesses. When I’m using washes, I am either trying to cover the whole model to create overall shading, or I want to create a black-lining effect by emphasizing the recess between two colors (think the trim of a shoulder pad). Adding a few drops of the flow add to a wash helps it sink into the recesses even more rather than pooling on the surface.
A 4 oz bottle of the Liquitex Flow Aid (which is huge for what we need it for) is only $9 on Amazon.