"George Max" wrote

You've said a mouthful. Being the guy I am, I had to learn the hard
way. I too wanted to use latex over a "varnished" surface at my
house. In my case, it was the risers on some interior steps. In no
way shape or form was that paint (Sherwin Williams superpaint) going
to adhere.

I ended up using a heat gun and stripping it all off. It was a time
consuming PITA, but the results after sanding the scraped surface is
perfect. A beautifully smooth surface with excellent adhesion.

I say strip the old surface in whatever manner you want then sand 'er
smooth. Then apply the paint.

Thanks, George.
I had an idea that stripping might be required but I didn't want to if I
didn't have to. On the other hand, I want a good finish and I'm willing to
do whatever I have to do to get it. I have a good heat gun and I can get
stripper. Which do you think would be better? I'm not fond of stripper
because of the fumes and the mess but if it's what I have to do, I'm game.

Max