On Aug 30, 4:51*pm, Don Foreman wrote:

.. After all of these processes, you have a short
window of time to get the first coat of etching primer applied before corrosion sets in. Depending on prevailing conditions, that
window is between 20 minutes and 2 hours.
Use of a passivating metal treatment will extend the window
considerably and will also aid wetting and adhesion significantly.

Whether you just neutralize the acid and wash, or whether you use
phosphoric acid, you should apply the primer as soon as the surface is
really dry. Tests done on aluminum treated with fpl *pretreatment,
found that the bond strength was highest with immediate application of
the paint. Just sitting around for a couple of hours produced lower
bond strengths. No corrosion involved. Just airborne contaminates.

Dan