I am an automotive painter with over 30 years experience and on the topic of clear coating or not clear coating the embossed area of a Coke machine, I have had very good success with the following procedure...
Once the decision of what color you would like the embossed area to be has been made, base coat the entire machine with that color choice. You should use a high quality base coat product such as PPG's DBC base coats or Sherwin Williams Ultra 7000 system. Next step is to clear coat the entire machine with 2 coats of high quality urethane clear such as the vendors listed above. Once the clear system has been allowed to dry for a minimum of 24 hours with or without a bake booth, you will then sand entire machine with 600 grit sandpaper, preferably with a DA sander. If you are not knowledgeable with using an orbital sander, then you may use 600 wet sandpaper and sand the machine by hand. You will need to sand between the letters with a grey 3M scotch brite pad....Do not sand the letters at all, leave them with a shiny gloss finish....I will ex pain the reason for this further into this tutorial...the rest of the machine should have a dull appearance and with no shine at all. Pre-clean with wax and grease remover and then paint the entire machine with your final base coat color including the embossed part. Once the base coat has had a significant
amount of time to dry, approximately 1 hour at 70 degrees or higher. Precede to sand the tops of the embossed
lettering carefully with 1000 grit wet sandpaper, until the underlying color appears. This is an important step as you do not want to sand beyond your 2 coats of clear...this was the reasoning behind the clear coat application. Use only the tips of your finger and light pressure when sanding the tops of the letters. Wipe down the entire machine with a quality
base coat tack cloth, then apply 2 coats of urethane clear coat provided by one of vendors above.
This is by no means the easiest way to paint your machine but it is a finish you can be proud of and the longevity will be much more desirable in the years to come.
I am located in North Carolina and if I can be of further help you may contact me at
myrustedjunk@yahoo.com