Experimenting with pigments

I recently bought several pigments from AK Interactive. I'm very happy with their washes, so wanted to try my hand at their pigment range.

One of my concerns is how to fix the pigment to the model, allowing someone to pick up the model and turn it over, without fear of removing the carefuly placed pigments with their fingers.

As a first experiment, I tried several mediums to dissolve the pigments in :

• Water
• White spirit (= "mineral spirits")
• Vallejo matt varnish
• Alclad II klear kote matte (basically : matt varnish)

Here you see all 4 tries (still wet) on an index card. The Vallejo varnish was a little thick, which contributes to a slightly ugly result. I'm not trying to get the most realistic look here. I'm trying to find out which medium keeps the pigments in place the best.

One remark about the white spirit. While the other mediums all dissolve the pigments, effectively creating a kind of "wash", the white spirit does not dissolve the pigment and you get a kind of fluid in which the particles are floating.

If you apply some dry pigment to a surface, and then apply white spirit with a brush or dropper, it engulfs all the pigments, but does not disturb their placement. (Unfortunately, it also does nothing to "fix" them in place, even though I was told it would.)

Here's the result, all dried up. On the left, all is still undisturbed. On the right, I just pressed my finger against the card.
As expected, the 2 varnishes have sealed in the pigments. The test fixed with water is relatively undisturbed, but the test with white spirit is simply dry pigment, which slides right off the card.

A little tougher testing. On the left : smudging with a finger. On the right : scraping with a tool or nail.
The pigments fixed with water or white spirit come right off. The ones with varnish stay put.

Test results :

• Water and white spirit are bad fixers for pigments
• Any kind of varnish will do the trick

Problem still remains : now that I have an idea on how to keep pigments in place, how do I apply them to achieve a somewhat realistic look?