David Nebenzahl wrote in news:485ab17a$0$18941$ snipped-for-privacy@news.adtechcomputers.com:
How bout a reply from E.F. Hutton. Will that carry any weight?
Yea man. Iz got sum sticky sheeeit in it that hole up onto other shit real good. Iz like...iz like...iz like, well, iz like that sticky shit ons the backs of dat metal tape weez hole broken shit together wit.
One cleans up with water and the other thinner. Not sure which is which though.
Yes, they are usually supplied to a buddy with a drinking problem along with a case of beer and a bottle of Jack.
The primary purpose is to provide a surface with uniform absorption characteristics. It does that because it *does* have more solids (that is also why it is heavier.) I haven't checked to see what the solids are nowadays, used to be stuff like whiting (powdered limestone). The solids also help provide a smoother surface by filling in grain and minor surface scratches/dings.
With luck, the primer will also be easy to sand so you can do so and get a baby-butt smooth surface. Most aren't. ____________________
Well, duh. Oil based primer has oil in it :)
Actually, it has a higher proportion of oil (compared to "paint"). That means it is relatively soft when dry and that means it resists chipping or loss of adhesion. That is also why it doesn't sand well...for a prrimer to sand easily it needs a high proportion of solids and less oil. Get one thing, lose the other. _____________________
Any paint. It will just require many more coats to get to the point that one coat of primer will give. ______________________
Which is why I didn't bother talking about latex.
I suggest you pony up the cash to award a grant to a MIT grad student...or maybe write your senator and ask for hearings on the topic.
And yes, welcome to 2008. Usenet is indeed dying largely because there are faster and more reliable ways of finding information on something called "the internet".
For a reason to use an oil based primer...a few years ago I was painting new walls with Benjamin-Moore's water based primer and it looked horrible. Black and gray spots all over. Benjamin-Moore sent a chemist down and in a millisecond he put his finger on the problem. The drywall that had been used was manufactured in Canada and used recycled newspaper to create the facing. The inks dissolve in the water and carry through the water based primer leaving the small black to gray spots.
He had me switch to an oil based primer and the problem disappeared. Still used a water based acrylic for the second coat.
I was going to thank you for a useful link until I saw this was an ad for a book--for $195, no less. Thanks, but no thanks. (Now, if my local public library has it, fine, but I doubt that.)
You should learn more about how Wikipedia works. Studies have found it just as accurate and more up to date than the Encyclopedia of Britannica, but I suppose both will pale in comparison to the accurate information you can solicit on Usenet :)
... I find it an interesting set of questions. While the OP can be faulted for clarifying his question in a manner that some found undiplomatic, I can understand his desire for the the theoretical how and why of primer vs. topcoat rather than the empirical knowledge that most of us have from having applied these coatings. I also appreciate the few (such as Frank and Smitty Two) who actually tried to answer the question.
: 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)
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