I was reading in The Haynes Automotive Body Repair & Painting Manual ( 1989 ) that after polishing, you can put a sealant on before you wax in order to give better, longer lasting protection to the paint.
However, when looking at sealants from a variety of manufacturers like Chemical Guys, Wolfgang, McGuiar's, etc... I get the impression that they are meant to be used in place of wax and not as an additional layer in between the clear coat and wax.
Which one is correct? Has the technology and practice simply changed since the book was published in '89?