This is a series of tests I did to try and figure out common materials to recreate this ancient (and very beautiful!) technique. Here is a traditional piece
I started by trying three "paints" on three whites I used Ultramarine fines (the medium blue), China paint (the darkest) and Prussian fines (the lightest) all mixed with a water medium that I got from Coral Schaeffer (#1368) Iused 1010 Undercoat, 1020 Titanium and 1030 Foundation as my whites. You will see that the Prussian fines did not scratch very well.These were just initial tests so I didn't put too much effort into the design ;-)
The next level of test were influenced by an observation that my apprentice Alex Bolduc made - noting that the colour inside the lines was underneath the scratch marks - and must have been painted on before scratching - so I decided to try painting both the background and the pattern before scratching. I had eliminated the fines after the first test - I didn't have enough control - they were too 'slushy'. In the subsequent tests I used only blue china paint mixed with Coral's water medium. It is very slow to dry (at least 10-15 minutes on top of the kiln before it is dry) as opposed to the Thompson acrylic blue (which was the only other colour used in these tests) which dried very very fast.
The first tests were done of 1030 Foundation white
I scratched a line around the bottom design - but when fired the enamel paint spread and covered the line
The next tests used the same paint material - but were on 1010 Undercoat White
In the final piece (base 1020 Titanium) I tried putting the acrylic paint on quite a bit thinner when it was a base coat. This worked much better but for some reason it would not flow when it was painted over the china paint
Now for the final tests I eliminated the 1030 Foundation - the paint seemed always to go too blurry with this base. I felt that the china paint lost it's brightness and became to much like navy on the 1020 Titanium - so I used the 1010 Undercoat for the final tests.
I mixed the china paint with white liquid enamel - but I had the same problem with it not flowing. I am very happy with the turquoise background - but will need to go out an purchase some white china paint before I am entirely happy with the darker blue.
The red was Thompson Acrylic. It is by itself on the turquoise piece - but I thought it needed to be deeper - so I mixed it half and half with brown.
The trouble with Thompson Acrylic - is that the palette is limited to 12 colours - while china paint can be purchased in an unlimited palette. I will be doing some more tests with different mediums (I am going to try an oil medium today) so I will keep you posted!