Acrylics over enamel paints

Are you painting over a gloss? In that case, you're going to find that painting with an acrylic is probably not going to work very well no matter the paint you try.

You're better off trying to mix the proper color in a similar enamel.

I hope this is the end of your acrylic woes.

When I switched from Humbrol enamels to MM acrylics I ran into watery paint and lots of bubbles forming. Some colors I got away with stirring by hand (armor sand) but when I tried Russian Armor Green it was a no go. I got some advice, got the mixer and the problems went away. 

I don't know if this applies to you, but while you can get away without using primer with some enamels, acrylic will just peal/flake off easily without a primer coat.

I was doing the light colors first, the darker gray seeped through and didn't work.  Since I have just been informed that acrylics take more stirring then by hand, I will have to redo the darker grays all over again.  At this point, I may just sand it back down, prime and repaint all over again.  As for the yellow, I will do sand, and add a base of white paint before the yellow.  After I do the grilling of course!  :)

From what you have said, it sounds like you're stirring the acrylic paint by hand and that would be the problem.

Enamels mix by hand well, most acrylics require more mixing then is reasonable by hand (eg, using a small stirring stick).

I suggest a Badger paint mixer (google search / images to see what it is) or a dremel tool with a tooth pick/flat spur to properly mix acrylics. Don't forget to use a splatter guard (eg, toilet paper roll) and let sit for about an hour to let the bubbles settle down.

-edit- Oh and light colors over darks = very bad things. Paint from light to dark if possible, as has been stated in the thread you may need a special base color for that yellow and other such light colors.

For your problems with yellow (a consistant problem with many yellows, (acrylic or enamel in my expereince) try putting down a base coat of white or yellow zinc chromate first... Yellow paint is always a bear to apply for some reason...

Will give that a try, thank youi.

You may be able to remove the acrylic using denatured alcohol without it affecting the underlying enamel.

Thats good to hear.  Last night I had to work on the model, took off the paint and the acrylic paint worked its way under the tape.  So I will have to sand and repaint the model.  This is defnitely becoming a learnign expereince.

You will find that it's a characteristic of the paint itself rather than an issue of different paint mediums. Painting acrylic over cured enamels is no different to painting with the same paint over bare styrene. In fact, painting over a cured flat enamel will arguably be better than painting over bare styrene as it provides some "tooth" for the acrylic coat to grip to.

The Model master acrylics is what I am using, over Model Master enamels.  it is beading, and for lack of a better term, regardless of how I am mixing it, it is just not giving alot of coverage.  Yellow is coming off as very light even with multiple layers when applied over a gray base.  is wear, this Enterprise model is givign me a headache.

A few questions

1 - watery how? Is it beading up? If so you need an agent to break the surface tension. Depending on the paint, a drop of dish soap or a spritz of windex in the mix can really help. If it's just watery as in too thin/no coverage, how are you thinning it?

2 - what acrylic are you using? I've found some acrylics brush paint very well (Vallejo and Lifecolor), and others I can't get to work to save my life (specifically Tamiya, though IMO Model Master Acryl is a bag of hurt, too).

Typed so fast, I forgot to add.  I am finding that it is coming on either too watery using acrylics.  I tried to apply a dark gray over a lighter gray that is enamel based paint.  The results were alot to be desired.  First time using acrylics for a model, so I am uncertain if I am doing somethign wrong since I am using a brush and not an airbrush system, or do the two just do not go well together.  The enamel paint was dry before I applied.

What specific problem are you having?