What causes paint to become chalky?

[ErikB]

I'm still working on those BoB Tropical Brits and having difficulties painting the khaki.  This is strange.  I've done this 100 times with other minis but I'm having an odd problem.

I put down a khaki (Vallejo) basecoat, apply thinned GW Mud wash mixed with the base coat, and then drybrush basecoat back on.  It comes out very chalky.  The highlighting is Dheneb Stone mixed with basecoat khaki and then just Dheneb Stone.  It is also turning out a little chalky.

By chalky I mean that the granularity of the drybrushing is large and not smooth.

Anyone know why this happens?  Or how to avoid it?

[Gandalf]

As long as you're leaving plenty of time between coats so that the paint below isn't being rubbed off by further applications, the biggest factor is probably the age of your paint.  Have you tried the same technique with a new batch to see if the same problem occurs?

[ErikB]

Oh, that makes good sense.  I've been using flow improver which slows the drying time, so the lower layer may be a little wetter that usual.  And the Stone paint is very old.

Alright, time to let them dry longer and go to the local GW store.

Thanks heaps.

[Gandalf]

You're welcome. Glad to have been of help.

[ErikB]

I just did a layer of highlighting today with the base coat and then bleached bone plus base coat.  The minis were slightly tacky from the flow-improver.  Letting them dry for a few days seems to be important.  Also, the bleached bone paint was brand-new (and the base coat is still young).

Your advice was dead-on.  Thanks again.