The tools I used the most. The two on the left mostly with a predilection for the losange on the brass
I have couple left over engraving on bones for a repair we did on a bargueño those where a little or not deep enough so we have them. The bone is very brittle like the horn or the shell and the side of the engraving tool the “burin” needs to be real shap to avoid excess splitting and jagged edge on the engraving lines. So I use it to test the sharpening for the shell engraving
Brass is really tough on the tool and I need to resharpen often as soon as the point is dull, otherwise you rip and this is not good. Each time you sharpen you have to test your attack angle to go straight and not get draged deep in the material, that it turns well or permit regular straight lines etc…
Then pore-filling (more accurately gap filling) and engraving line filling with a mix of pumice and black ash first then ash alone.