I just got through painting an entire Warhammer Fantasy Dwarf army with no issues. With my new 40K army, however, I've been having a darn near impossible time with gold trim. I'm not sure what I'm suddenly doing wrong. Everything I'm trying to do with metallic paint is coming out blotchy as heck, even after a bunch of layers!

For example, these guys I just got done with a test painting: http://i.imgur.com/EYiQGyH.jpg. (These two dudes are some used models I picked up to test color schemes out on. I wasn't as neat on some of the edges as I normally would be but my intention was to strip them down and do them right once I was happy with my choices.)

It's most noticeable on the shoulder trim on the right guy. That was after 4 layers of paint. I didn't have this problem with my Dwarves but part of that might be because their golden fiddly bits were much more fine.

Paints: Vallejo Model Color Old Gold Vallejo Thinner Medium in a 1:1 ratio.

Thanks in advance for any advice you may have.