How were Ford Model T body's painted?

Re the Ford Model T how was paint applied to the metal? Brushes, spray guns or dipping or what?

All of the above.
4rth paragraph.

Black (that is a little bit of a myth). Early ones came in lots of colors…except black.

The process used to paint them was a baked enamel process called japanning. Black just happened to be the color that dried the fastest so it was used almost exclusively for the later model years.

*"According to Model T expert Guy Zaninovich in Ann Arbor, Mich., cars were painted using a process called japanning, which today would be called baked enamel. “It was first used in the mid-1800s for decorative items imported into America,” Zaninovich says. “A piano has a shiny black surface that almost looks like plastic rather than painting because it was done with the japanning process. It leaves a very hard and durable surface. The only pigment that it worked in is black. If japanning worked in hot pink, all Model T’s would have been hot pink.”

Akron Paint & Varnish Inc., the 125-year-old Ohio company that made the original black paint for Henry Ford, is still around, and it has the formula. CEO David Venarge says the formula came with the two founders from Germany. “The formula used tung oil, a cheaper replacement for linseed oil, car black pigment plus gilsonite, a mined mineral,” he says. “The paint was also used on mattress buttons, hooks and eyes, bobby pins and other hardware.”*

through the first decade of the 20th century, they were using spray guns to paint with whitewash. This was done with a large hose a bit like washing the wall.
Last year of it, Devilbiss developed a lacquer spray gun to lacquer furniture.
Binks developed spray nozzles for whitewash during the 1910’s and realised that compressed air and fine nozzles would give good result for oil type paints too.

Binks’ nozzles allowed spraying oil /thinner type paints,which were first used for cars during the 1920’s.

Model T’s body work were dipped then baked. Other parts may have been dipped or brushed, and baked or not baked.