colour in the engraving?

[yadnom1973]

I often see products like these little key rings which are sheet metal with an engraved pattern and then there is something applied to leave colour in the engraving. The coloured pigment looks glossy and thick, it has a high saturation and brightness and it is also very resilient. I’ve seen glow in the dark pigment applied to engraving in the same way. What is this method of putting pigment into an engraving? Enamel or lacquer of some kind? It feels like a more resilient and permanent way of applying colour?

[Rorschach]

Usually a thick layer of enamel or lacquer, sometimes coloured resin such as epoxy. Really high durability can be achieved by using something similar to powder coating where it is baked on.

[yadnom1973]

That's interesting. I'd presumed it was something heat cured or some such thing but I guess not, thanks for the input Rorschach.

[Rorschach]

Oh forgot to say, if it's mass produced the paint is likely a UV cure as that's much faster and easier than a heat cure.

[yadnom1973]

I’ve tried to research how to go about this and have found many accounts of people wiping nail polish and acrylic paint into the engravings but I find it hard to imagine this would have the same finish and be as hard wearing as the example above. Maybe I’m wrong, I hope so.

Has anyone tested out some solutions to this?

[Hitch]

I restored a brass plaque a few months ago. I filled the engraved letters with a couple of coats of humbrol enamel, then let it dry for a couple of days before flattingand polishing the brass again.

It worked well, but not the most efficient method of doing it on a production scale.

[jaeger]

I've tried various things to renovate tools like steel rulers, the best
so far is a solid paint marker like Edding 950, let it dry and then rub off
excess with card/stiff paper rather than a cloth which just seemed to remove it from
the engraving that I was trying to fill.
Some clock makers use shellac on dials and melt it in.
Somewhere on Youtube is the Starrett factory making rulers and
a man just wiping paint on then off and it's perfect! How he does
it I don't know, never works for me, but then my items are worn so the engraving might
not be deep enough.

[Job and Knock]

The type of paint is also significant. When we made some relief sand blasted signs many moons ago we were advised to use signwriter's enamels for the coloured background areas. Unlike ordinary paints these have an extremely high solids content and seem well able to adhere to glass, metals and timber. I believe that the brand was "One Shot" (American) and that they were bought from Wright's of Lymm (?) although Bollom & Keep (now no more, sadly) and Handover's in London also supplied them.