Glossing straight over Zinsser BIN.

Shellac based sealer and not necessary an undercoat.

Give the customer the technical data sheet.

Not recommended for whole surface exterior application or for application to floors or decks or surfaces subject to immersion or prolonged contact with water. These limitations are not to be construed as all inclusive.

Dry to the touch in 20 minutes and can be re-coated in 45 minutes. The dry primer film develops full adhesion after it cures in 1 to 3 days. Lower temperatures, higher humidity and the addition of tint will prolong dry and cure time

Would a water based paint stick to a shellac coated surface over any length of time.?

Thanks Alan, that's decided me. Although I'll be using the oil based weather shield gloss the same principle applies. I'll use the undercoat.

There used to be two types of weathershield undercoat.

The DIY version sold in the sheds was water-based, while the PRO version from trade outlets was solvent-based.

The primer-sealer is now only water-based and is almost impossible to use outside if the temp is below 20C.

I have discovered the best way to use it is fill an old oil can with primer-sealer and gently squirt/dribble it over the timber while rubbing it into the grain with a synthetic paint brush. This way, even though it is water-based you can do vertical and overhanging bits of timber without too much running down your arms.