Robert11 wrote:

Hello,

Not very sharp re painting.

I know latex paint over oil paint is O.K., but have have heard that oil over
latex is not.

Is this universally true, or... ?

What actually happens ?

Thanks,
Bob




No. Not universally true. It depends, in part, on whether the alkyd is
enamel or flat. I don't know
of a book that says so, just my own experience. Latex semi on top of
alkyd enamel is a bear. It doesn't
adhere well and is difficult to repaint, especially on doors and trim,
because it won't sand. Sanding makes
the latex roll and/or peel. If properly cleaned, deglossed and primed,
it might work better. Either kind
of flat over the other probably works fine. If a latex paint is smoothe
and clean, you can probably put
alkyd paint over it.

There is a big difference between "dry" and "cured"....if one type is
put over the other without sufficient
curing, it would likely cause problems; this is where oil and water
don't mix and the rest of the curing
gives off vapors that are trapped.

Here in Florida, most new building is concrete block and stucco. I have
read that acryllic/latex semi
is the preferred exterior paint for that. Lots of folks, from what I
read, are using water based paint
for wood siding, but haven't seen it around here. On oily wood, like
cedar and redwood, a stain blocking
alkyd primer should be used, I believe. Best to check out a webside for
a good paint company, like
Ben Moore or Sherwin Williams, for the particular project especially if
there are problem areas.