Dear Anelia,
First, thank you so much for replying to this thread. I appreciate it very much that you know how hard to paint with porcelain paints are. It is truly a dying art, unfortunately, but the longest lasting art of all media....so sad that more don't learn it in order for their beautiful artworks to last forever.
The portrait colors that are used in porcelain art today are of similar pigments (unlike the old ones where cadmium based and others, like silver or aluminum based yellows, which didn't like each other in the firing) and now one can easily use reds and yellows together with none or very little if any difference when firing.
So, reds can be added at any firing. The trick with reds is to paint very thin application because when it gets thick, and if fired hot, will turn almost a brick red.
Porcelain art is all about glazing and letting the porcelain shine through the paint.
Thank you so much again and I do hope that some day you might give porcelain art a try again.
Also, I'm the International Porcelain Artists and Teachers, Inc., Chairman of the Board this and also the Editor of the Porcelain Artist magazine. I am always looking for porcelain artists to feature in our magazine. If you have work to show featuring your porcelain....please contact me through IPAT at the website:
http://www.ipatinc.com
I'd love to see your porcelain art work if you would like to submit it for consideration in the magazine.
Here are some great porcelain artists currently teaching worldwide:
http://www.gotportrait.com/
http://www.atelierdebercy.com/
http://www.andreasknobl.de/
http://www.artfilipe.pt/