Medium v retarder Et. Al.

I'm not certain about the particular paints in question, but as a generalisation;

Reducer, often referred to as "medium" contains binders - this allows it to be added in whatever amount required without having any drastic effect on the paint other than reducing the amount of pigment in the mix & making colours thinner / more translucent as more is added.

Thinners do as the name suggests - they don't contain any binders & can only be added to the paint to a certain point, after which the paint will not adhere or coat properly.

Retarders, improvers & flow aids behave in the same way as thinners - they contain no binder, so can only be added to a certain point.  

Medium won't give that much difference in performance & is most often used to stretch the paint or soften the base colour. I'm not familiar with MM, but I would think that some testing with thinning ratios & the addition of a small amount of flow aid or improver may help. 

You can use Golden Medium GAC-200 as an additive to your Acrylic paints to get them to adhere to your model better

that is what I use it for with MM, PolyScale, and Aeromaster (LifeColor, sometimes, also)

you can literally use Golden 200 and mix in Gauche tube Acrylics (in tiny quantities) and make your own home made Acrylic paints

the Flow aids and drying retarders are used in extremely small quantities,,,,you use Flow Aid to get your properly thinned paint mixture to be "wetter", allowing lower air pressure,,,,and you use Slo Dry to give the paint more working time before it dries, to allow longer brush stroke time (paintbrush) or to allow the paint to spray through the airbrush better before it dries on the tip.  Just don't use either Flow Aid or Slo Dry straight,,,,,,you mix it per directions, and then use tiny amounts of the mixture (directions are on the bottles)

Rex

Thanks for all the input.  I think I found the mixture that finally works for me.  I have the Badger Velocity spraying at about 14psi.  I mixed the MM acryl to the Golden Medium at about 1:1.  It sprayed out of the very fine tip velocity with no issues at all.  I would get some build up on the tip, but a quick wipe with a cotton swab soaked in water did the trick.  I sprayed for about 15 minutes on and off and never had to do anything more than wipe the tip.  The paint did go on a little wetter and had a bit of a sheen, but after 15 minutes was not tacky to the touch.  I will let it cure overnight.

I needed no thinner or retarder.  Camo schemes now seem in my future:)

John