Humbrol Gloss / Matt Cote

[Starfighter]

I've been using the above products for some time now, as they overcome the yellowing effect that you can get with conentional varnishes, but I have a couple of questions.

Firstly, are they acrylic  or enamel based, as although you can thin them with normal thinners or white spirit they dry extremely quickly, unlike normal enamels ? Also, even after a year or so they seem to be slightly " tacky " if holding your model for any length of time, which is why I use cotton gloves. One other point . . . you can't paint enamels over the top of gloss / matt cote ( Ask me how I know ! 😖 ).