On Sun, 30 Aug 2009 15:42:39 -0400, John wrote:

easyguy wrote:
easyguy had written this in response to
http://www.thestuccocompany.com/main...nt-313727-.htm
:
Wow, I googled the same subject and wound up here. I thought it was a
great question... I find it frustrating to try to find answers to things
from "experts" in the field, and only get those bland answers that aren't
worth reading. I actually wanted to KNOW what the difference was, but I
was shocked that almost everyone who answered mocked and ridiculed the
questioner. I went through every one of the eight pages to see if ANYONE
had a normal answer... not super-scientific, just a normal answer IF THEY
KNEW IT! Jeez, that's what I hate about looking things up online, is that
you get all these wise-cracking guys with nothing better to do than sit at
their computer and type in useless information, when some of us actually
want to learn something from guys who might know something. I would hope
that if you don't know the answer to someone's question, you wouldn't
respond, and let someone who WANTS to share their knowledge respond. The
whole thread on this topic was a weird battle between idiots... I couldn't
believe it. I had to register just to post this comment, because I was so
perturbed by the weird immaturity of most of the responders. The
questioner never got an answer to the question, and neither did I.




I wasn't following the thread so I don't know what was previously said
so here's what I've been told many times by many different paint stores
and articles: Paint has very little binder to make the new paint stick
to and cover the previous coats or bare wood. Primer consists of mostly
binding agents. When I painted my house (going from a dark color to a
much light color), I first power washed the siding with soap and water
to remove the grim then primed by brush. Afterwards, I spray painted.

Primer feels like you're painting sandpaper onto the surface and it's
tough on paint brushes and equipment.

I don't think you'll ever find a contractor who'll ever prime since it's
an extra step and he'd have to charge more. Also, most homeowners don't
know and don't care about the quality of the paint job so long as it's
the "right" price and the contractor didn't spray paint the plants
and/or the cats.


Primer is "generally" a more porous finish that allows the finish coat
to "bite" and therfore stick better. As stated above, primer is
generally "stickier" - bonds better to the surface.

Some new generation paints (G3 latex) is "self priming" and "alkyd
modified" latex sticks better to chalky surfaces because it "fixes"
the chalked surface.
The other reason for using primer is to make the surface a more
consistent colour. Tinted primers reduce the amount of finish paint
required to cover - and can actually reduce the TOTAL amount of
product required.
A "primer surfacer" also levels the surface, helping hide minor
imperfections.

Any contractor painting drywall without priming is just wasting your
money.
Repainting a house (external) that has had paint peeling without spot
priming is also wasting your money - and a contractor who painted my
house WITHOUT proper priming would not get paid. PERIOD.

I just had the exterior of my house (aluminum siding) repainted last
summer with a G3 alkyd modified 100% acriylic latex and the contractor
spot primed all bare spots before painting. Excellent job and it will
likely last as long as the original finish (house is 38 years old now)