Epoxy fairing over foam sandwich cores

Say you want to fair a large area of hull 0.064".

Is it necessary to precoat straight epoxy when fairing over large area of hull? Precoat and then allow to tack?

Or if you rough the substrate and clean it well is that sufficient to just add fairing compounds?

Does it make a difference if the substrate is smoother or rougher to start?

This is for paint prep.

 

The only reason to precoat is if the substrate is porous. Prep in the same manner you would if applying an additional layer of lamination. You know that an un-etched surface lacks adhesion potential.

 

What do you mean by etched surface lacks adhesion?

 

My bad. Missed proof reading.

Should have said;
Un-etched surfaces lack adhesion.

Thanks for bringing it to my attention

 

Want to edit and clean up the thread?

I will.