I hadn't done one of these in about 20 years and we did them differently back then. So when I saw Cali4Dawn's directions, I realized that some people would not understand what the correct texture needed to be for the icing to work. So I experimented and created my own icing for buttercream transfers. It works fine, had no trouble with using black colouring in it for outlining, I now use it all the time. No expert here, I have only done a dozen or so, but it seems to work well for me and for other first-timers I have sent the recipe to. Just follow the Cake Central instructions Dawn put under Articles, Tutorials and follow these in addition. I copied the post I made on another site, www.r-bdesigns.com
and they follow.
Just go without about 1/4 inch of colours and top that off when set with some more icing of the colour of the top of your cake.
So I played with the icing until I got the right consistency and here is what worked for me. It also worked just fine for the black outlining, I didn't have to freeze it or dry it before continuing with the other colours. All I did was add black Wilton paste food colouring to a small portion of this icing, no special fudge icing or Wilton black icing ready-made or anything.
So you are going to follow the usual steps. You use a sheet of plexiglass or a board that can go into the freezer. You tape your picture on well. Cover it with waxed paper or preferably parchment paper and tape it well too. I had my brother-in-law get a 16 inch square of plexiglass cut for me, I figure that would be about the biggest size I would ever use for anything, but you can get various sizes cut.
1/2 cup Crisco shortening
1/2 cup butter, softened, I use salted
1 1/2 tsp. vanilla extract, I used the pure brown, but you will get an ivory tinge to your icing so you can switch to clear (the brown really does not affect any colouring except your white will be more of an ivory, but for eyeballs etc. it isn't noticable)
2 cups of sifted before you measure it out, icing (powdered) sugar
No other liquid and you don't need to dip your spatula in hot water or any of that stuff!
Blend butter on low until softened. Add Criso and continue on low. Add vanilla and continue on low. Add icing sugar, one cup at a time and continue on low until well incorporated. Then colour and apply. I use a tip 3 for outlining and a tip 12 for filling it in. I don't use a coupler in my icing bags for this. You can use parchment bags with just a tip cut off the end or whatever. Let it set for a few minutes and dipping your finger in icing sugar or cornstarch smooth out I dip my fingers and use a gentle pouncing motion vertically. When all colours are done and set a bit (usually about 25 minutes or so), smooth out with a spatula (again I sprinkle on some powdered sugar and again I sort of gently pounce down vertically so as to get rid of any wormies or such and apply your backing and outlining colour. Again smooth out with a spatula, once set. Now I also covered the finished product in parchment paper, then inserted the whole thing in a green unscented garbage bag and froze it overnight. In the morning I take it out, flipped it onto parchment, lifted off the waxed paper and then reinserted it with a piece of parchment over it, back on plexiglass and back in freezer if I don't need it, for up to two weeks. But really these freeze up in a chest freezer in about 90 minutes. It is solid enough that you don't need the plexiglass on it to re-insert in freezer, I just do because I needed a flat surface as the freezer is pretty full! You could just put it parchment paper and all, into a freezer bag.
Hugs Squirrelly Cakes