Please correct me if I'm wrong (as I'm not familiar with this technique but would like to begin working with it), but there seems to be several different approaches to painting on cakes:

- Gel food coloring + vodka (or lemon juice)

- Royal icing

- Colored buttercream

I tried the first technique last night, but it wasn't what I expected. The colors came out very "watercolory" and almost iridescent. Which of these techniques will give me an opaque look? (Something more like this or this)  Would I get better results just using the gel food coloring without diluting it? I'm not entirely sure the purpose of diluting it, so it was hard to assess whether the technique would work if I didn't. I'm just looking in general for an explanation of the different approaches and how they're different in terms of results on the cake.

I also noticed AmeriColor has these airbrush colors (http://www.amazon.com/dp/B002L3RVC4/?tag=cakecentral-20). How are they different from the "regular" coloring gel AmeriColor sells? 

Thanks so much in advance! :)

I just purchased the americolor gels and airbrush shimmers.  The gels are thicker and the airbrush shimmers are more liquidy and have a definite metallic glimmer to them.  I would imagine a thicker medium would give you the opaque look.  I have never painted on cakes so not much help there but I could help with the difference between the americolor products.  

It is lemon extract, not lemon juice. Used to evaporate quickly and not make the fondant gummy like water will.

Buttercream is too thick to "brush on" in any way to paint as detailed a picture as you want. You can use it to make a frozen buttercream transfer, but not that effect.

Same idea with royal, unless you were adding a "puffy" 3D effect.

You can paint with any food coloring, using the vodka or lemon extract to thin as needed. Powders can be made into "paint" the same way--- even the petal, shimmer, and luster dusts (with varying degrees of "edible"). You adjust for drying time, and how opaque you want it. Painting with "pure" food coloring, food coloring gel, or airbrush food coloring all works.

Incredibly helpful! Thank you so much! :)

You can also try using cocoa butter or shortening as a base for mixing colors. Cocoa butter has a more opaque look and using shortening has an oil paint look

You can also use titanium dioxide, which is the white food coloring, to make food coloring paint. That will give you an opaque base to add the color to.

 I've painted with buttercream before, you can thin it out with corn syrup and water.  It works more like an oil paint.

I've always painted with Americolor gels and vodka.  When doing so, I always have a 'spare' piece of fondant rolled out (in the colour of the cake) and I practice the colours on that first to make sure it's the right colour/consistency that I want.  It sounds like perhaps, on your first try, there was too much vodka added.  Having the 'spare' piece of fondant really helps.  Hope this helps!

I've done painting with gel colours and vodka on a few cakes now. Nothing major, but it's come out ok.

Best thing I got was a cheap little plastic palette mixer, similar to what you would use for kids paints. I actually got it from a bargain store, what we call a Pound shop in the UK. It's simple but effective, lets me mix the colours to suit and very easy to wash off quickly as I change colours.  

I do like the idea of a spare piece of fondant to practice on, that's a great idea and one I'm going to steal :D

I never would have thought of using shortening! Great tip. Thanks. :)

The spare piece of fondant is a phenomenal idea! I think you're right; I probably added too much vodka. Perhaps I'm only supposed to add a couple of drops? It was very watery after mixing, so I'm sure that's where I went wrong. 

I will definitely try diluting with a bit of vodka (or even using the gel colors without anything added, as another member suggested). Thank you so much! :)

I use the gel colours to paint with predominantly. I use an eye dropper to add vodka drop by drop to get the thickness and colour intensity I want.

The vodka is just to thin the gel enough to paint with although it can also lighten the colour of you add more.

The photos look like powdered colors in alcohol.  I've used lemon extract before but got an overwhelming lemon odor that was a real turnoff.