Dunder: surface growth and vinegar smell

[Denizh]

I collected the dunder from my stripping run two weeks ago and kept it indoors in my distilling room. Last week there was a fuzzy spot on top and still smelled of dunder, this week the growth covers the surface and smells mostly of vinegar.

This is absolutely the first time I am doing this and wondering if I am on the right path to establishing a muck jar.