Richard, a 'properly made' wash such as any commercial product out there is merely enamel paint thinned with white spirit. Don't be sucked in by the marketing blurb!
Flory washes are slightly different in that they're water based with a clay additive to aid keeping the wash in the panel lines.
As long as you apply any wash over a well cured gloss coat, you're unlikely to mess it up. Most problems occur when people add an oil-based wash over an acrylic gloss coat before its fully cured. Then the chemically hotter wash affects the gloss coat, resulting in undesirable effects.
Patience is the watchword!