I want to test...
…the strength of acrylic painting medium to see if it does what I think it does.
How I’m going to do this is add some medium to paint and make a transparent wash using very thin medium, I’ll then thin some more paint with water and compare them when they are dry - I also want to test thinned down paint with water then when that’s dry wash on the same medium over the top, so the medium dries on top of it not mixed in with it. When it’s all dry I can test the binding strength of each by scrubbing them with a wet brush and see if they hold.
Using the same paint I’ve made two squares of wash thinned with water and 1 square of wash thinned with medium (the middle one), and I notice that while they are wet they all look much the same.
perhaps there is a slight difference in how the brush marks are held in place with the medium but merge together a bit more with the water (like water paint).
Now I will give it some time to really dry and then brush some medium over the top of one of the watered down washes ( this is called sealing it), and then I’ll let it really dry overnight before I do the scrub test.
The results are this - the paint thinned with just water rubs off with a little effort, the paint thinned with medium needs a fair bit more effort to move the paint, but the paint sealed with medium doesn’t move at all with a hard scrub, which is a little surprising, but makes sense thinking about it.
Imagine the strength of paint thinned with medium then sealed with more of it - practically bullet proof!
a recorded the scrubbing part for the record.
and here’s a little story from my sketchbook.