Horological Meandering

As for Urushi, this video shows the gist of it:

Also, Urushi has been used for high-end (for wealthy family) homeware (like porcelain) for a long time and last for a very long time (Urushi tends to get harder and harder as the time passes) from generation to generation in the family.  This video shows how it is done, away from watch dial application.

As for both Enamels... as far as I understand it, they are both very similar and slightly different from European ones.

Hourou (琺瑯 - actually it is "Horo" but confusing with horology, so I write "Hourou") is base plate is steel or aluminum and categorized as "homeware techniques" while Shippo (七宝) whose base plate is typically precious metals (gold, for example) is categorized as "Art crafts".  Both are heated at 800 - 850 degrees, but I suspect the glaze is somewhat different.  The history of Enamel is very, very old, not Japan-origin, thought to be originated in Egypt BC time.  Hourou and Shippo are both translated to Enamel - literally, Hourou means Enamel in the industrial products, and Shippp means Cloisonne (most Shippo products/ crafts are in fact made with Cloisonne).  But today, both are considered highly skilled crafts and for the watch dial, both are in essence, "Enamel".

Here is the video for Hourou - may look simpler to make and bake:

... and Shippo Enamel - may look more complicated and requires more skill.

Slightly different, but mostly the same.  Both are Enamel for sure.....

Hope this helps?

Ken