That was Humbrol acrlyic matt varnish from a (small) rattle can, a used one, though. But I also have never come across this kind of reaction, as if the varnish immediately dried up (leaving 3D "drops" behind) and lost transparency. WTF? 

that sounds like a problem with the matting agent,  possibly a batch with too much in, or that it had settled or split out in storage.     
drat and double drat

I have several bottles of Humbrol matt clear that I ran through my airbrush, which I no longer use, the results were generally quite similar (I really should toss them out).

I also noticed that it took a lot of effort to get it to mix properly,

I have the feeling that your rattle can uses a version of the same stuff &, even though I'm sure you used what one would expect to be a more-than-sufficient amount of shaking to mix the stuff, you didn't quite mix it as much as it needed to be & you now have a very concentrated mixture left in the can.


(Note: The finish was very rough & chalky to the touch.)

Déjà vu... 


H0 scale Danske Statsbaner (DSB) Class 'MD' (DB V200.5/BR 220.5), machine '1053' (What-if/Märklin 3021 conversion) - WiP by Dizzyfugu, on Flickr

My heart bleeds after all the work and so close to the finish line, but what else to do? 
Havo to re-procure some ingredients, though, including some decals and paint.

Aouch! That does hurt all the way up here! 

Feel your pain Dizzy.

I've had similar problems to that with Humbrol spray varnish and have gone back to using Windsor and Newton with a brush.

Totally sucks, Dizz, but at least it's fixable!  

Déjà vu, next part. Thanks to the fresh/soft paint the bath only took three days to do its job, and after some more cleaning the new primer coat can come soon.


H0 scale Danske Statsbaner (DSB) Class 'MD' (DB V200.5/BR 220.5), machine '1053' (What-if/Märklin 3021 conversion) - WiP by Dizzyfugu, on Flickr

On the good side of all this, this time around you have less work to do.

Gondor

Yeah, and there are some pitfalls I can avoid/do better this time. 

Boy, does that suck! And it was looking so good.
This is why my projects get stuck at the paint stage. I'm paranoid something like this will happen.
I'll go with the old product not mixed enough. Or just old.  If we could just see inside those cans to tell if it's still good or not.

Quote from: kerick on December 05, 2023, 07:19:19 AMThis is why my projects get stuck at the paint stage. I'm paranoid something like this will happen.

But there is no alternative - you can only go ahead. 



Primer is on, BTW, but things stalled a bit because I have to wait for the delivery of new paints. No compromises or hurry. 

Quote from: Dizzyfugu on December 05, 2023, 08:59:32 AM

Quote from: kerick on December 05, 2023, 07:19:19 AMThis is why my projects get stuck at the paint stage. I'm paranoid something like this will happen.

But there is no alternative - you can only go ahead. 



Primer is on, BTW, but things stalled a bit because I have to wait for the delivery of new paints. No compromises or hurry. 

There is always one alternative......start a new project!

I'm sure the new paints will work much better.

More of the same, just a little quicker this time... 


H0 scale Danske Statsbaner (DSB) Class 'MD' (DB V200.5/BR 220.5), machine '1053' (What-if/Märklin 3021 conversion) - WiP by Dizzyfugu, on Flickr


H0 scale Danske Statsbaner (DSB) Class 'MD' (DB V200.5/BR 220.5), machine '1053' (What-if/Märklin 3021 conversion) - WiP by Dizzyfugu, on Flickr

At least you have all those windows made already.