I've never used that Vallejo product but it should behave similar to pastels .
I scrape pastel sticks into a powder to apply .
I either brush the powder on and when it looks right I apply the AK enamel fixer to bond it to the surface .
You just dab a tiny amount into the dust and the fixer migrates across via capillary action .
It's a matt finish unless you use too much and then it can present too much of a gloss finish :
https://www.scalehobbyist.com/catag...luid/AKI00000048/product.php?kw=pigment,fixer
There are other brands such as this one from
Abteilung , I have not used this brand but I imagine they all perform the same :
https://www.scalehobbyist.com/catag...ixer/ABT0000P249/product.php?kw=pigment,fixer
Another way I do it is to spray down a thin layer of matt varnish and then immediately dust that surface with the pigment .
Once the varnish dries I dust off the excess with a soft brush .
Or ,
Usually only with terrain work , I dust down the pigment then overspray it with varnish -- but this produces a completely different appearance .
If you aren't already familiar with the Tamiya weathering sets that come in the little compact case ,
they are worth experimenting with .
The pigment is already mixed with a binder so you can just apply it and let it cure .
I think they make maybe a dozen or more sets with different colors .
Example :
https://www.scalehobbyist.com/catag...u=4&pg=1&ppp=48&sb=stocknumber_a&so=d&man=TAM