Once upon a time, in the dim and distant past, there was cellulose.
Much later, there was 2 pack cyanide-based paint which you had to wear an airline respirator to apply.
Then came acrylic finishes. That was during the early to mid 80s IIRC. They were pretty neat as far as I can remember.
Just imagine I've spent the following third of a century in a drunken stupor and kindly tell me what my options are today. I'm guessing it's going to be some sort of water-based stuff which sounds horrific but I admit I'm way behind the times and may be wrong on that score. I'm going to be needing metallics and they need to be formulated for spray application and high quality finish. How do I specify the colour I need and is there a by-post service where I can order by the litre? thanks.