Way back in the waning years of the last century, I worked at A.J. Hastings
Store in Amherst, Massachusetts.  They sold many things, but stationery and
office supplies were a big part.  We had a machine that would emboss lettering
onto many different surfaces.  We primarily did pencils and leather or leather-
like  binders and diaries.  We charged by the impression and the number of
letters.  Color choices were gold, silver, white and black, iirc.

It was a heat transfer process, we built up the dies, not unlike compositing
print on a letter-press, which was held in a fixture that heated the type,
(brass I think).  The object to be printed upon was held in a clamp and a sheet
of dry transfer media was placed between the object and the die.  When it was
pressed together, the heated die struck an image on the object and the heat
transferred the ink or color into the struck image.  The media used had a heat
tolerant film backing, likely Mylar or something.  After finishing you burnished
the object to wipe away flecks of the colorant that went for the ride but didn't
belong.

The color media looked like little strips of carbon paper, well the black did
anyway, but must've been wax based as it transferred readily to the pencil (I
did a lot of pencils), but when cooled, remained in the impression and was
permanent.

It took some fiddling to get it the heat and pressure just right, too hot and
the letters spread, making the Os filled and blurry, same with too much
pressure.  Too little heat and the letters didn't fill entirely.  Or were faint
and spindly.

But you soon got the hang of it.  All the time I worked there, the pencils we
used were ones we used for practice with names or slogans covering every
surface.

You might try heating your punches and using Carbon paper to set the color?
Practice on scrap of course.

David Carroll

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