Here is the recipe/procedure, as I do it:
Ingredients - quick lime powder, (red or yellow) lead oxide powder, commercial lye cyrstals, water.
Procedure:
1) mix two parts lime powder into one part lead oxide powder
2) mix three teaspoons lye cyrstals into one cup of water. O.K. if water is warmed, as this will facilitate lye going into solution. Water quickly loses its heat so it is not critical to have the water very warm. Caution: avoid breathing fumes from this mixtures as the reaction takes place.
3) Take a very small amount of the lye water and add it to the mixed powder to form a paste. Just enough to get the consistency needed to apply the paste to the area on the horn you are planning to decorate.
4) Once the paste is applied to the horn, allow it to dry and become crusty or lighter in color as it dries. If not reacting enough, or if it doesn't appear dark enough to your liking, re-charge the reaction by carefully applying just enough of the lye water to re-wet the paste on the horn surface. Repeat, until you feel decoration is dark enough (15 to 20 minutes).
4 a) As an alternative, you can also apply a little heat to the paste as it dries by heating with a heat gun or with a torch. Be careful not to scorch the horn when doing this.
5) Once desired degree of color has appeared, wash the dried paste off the surface of the horn, and viola, presto, change-o you should have new decoration on the horn.
6) Repeat if needed to achieve full color.
Notes: I always wash the surface of the horn with soapy water (dish soap) prior to application. I have also washed the surface with the lye water in advance to "pre-treat" the surface with the strong base. This may help to get better color, faster.
