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-   -   Is gray primer best? (http://www.hotrodders.com/forum/gray-primer-best-59028.html)

cboy 03-02-2005 01:03 PM

Is gray primer best?
 
Just had a long chat with my local Car Quest store manager (good guy - avid biker) about shooting my rat rod project. When I said I wanted black for the fill/sanding primer he gave me a very interesting lecture on gray as the prefered primer color. I always thought, what the heck, one primer color is the same as the next (unless your paint mfr recommends a specific primer color to support your base coat color). But my Car Quest guy says many years of research show that gray is the best filling and best covering primer there is. Anybody ever hear that theory?

Dewey

rick458 03-02-2005 01:05 PM

I would also like to know and will be buying Primer in a week

302 Z28 03-02-2005 01:58 PM

That is a new wrinkle on me. The color of primer has very little to do with it's filling properties. Most primers that come gray as base can be tinted to just about any shade you want, does that reduce their filling properties?

Unless he is talking about primer from a rattle can.

Vince

mikeweyman 03-02-2005 02:03 PM

the nason 2k yellow is for overall coating,they have a grey 4k for spot spraying,as far as i know there is no color specifically for any job.mike

BarryK 03-02-2005 02:19 PM

That just kills me!
I hear from some shops that they won't use red because it will crack and some shops grey will crack.
Fill difference on colors?
Here is how we do it so you can figure out yourself if there is any difference at all in fill rate.
2500 gallon vat is the primer, its all made and in the color of the core resins, kinda a milky color. Now we add white tint to the whole batch because the first 500 gallons pour out will be white.
When that is done we will add x-amount of black to make our grey and we will pour out 1000 gallons. Next we will add black to the remaining so we have 1000 gallons of black primer. (tint is powder)

Fill rate difference 0.

Is there any difference? fill rate no, but the more black you add the
the slower dry because black is the slowest drying paint.
An example with the above primer at 30 minutes the white is ready to sand
the gray at 32.75 minutes and the black is ready at 35.25 minutes.

Beenaway2long 03-02-2005 03:02 PM

I'd ask for a tech data sheet.

MY BET is that he has TONS of old gray that he wants to peddle.

BarryK 03-02-2005 03:26 PM

Quote:

Originally Posted by Beenaway2long
I'd ask for a tech data sheet.

MY BET is that he has TONS of old gray that he wants to peddle.

************************************************** **
A further note, in the other two primers we make in buff and gray only and 90 percent of the sales is gray in those primers, so he probably knows this and is assuming why.

cboy 03-02-2005 07:30 PM

Quote:

Originally Posted by BarryK
A further note, in the other two primers we make in buff and gray only and 90 percent of the sales is gray in those primers, so he probably knows this and is assuming why.

Actually he referenced some Dupont research that had been done regarding gray vs. other colors. Next time I'm in there I'll have to press him for some specific documentation. I've delt with this guy on other car related issues and he's always seemed to know his stuff. This is my first paint purchase from him however.

baddbob 03-02-2005 09:08 PM

Just my opinions-no scientific data but for me primer color offers only two functions. Primer color can help or hurt paint color coverage- some colors of paint cover some primer colors or shades better than others and can make a big difference on how much paint you will use. Also related to color coverage would be rock chip damage- major differences in color from paint to primer will show rockchips much more than if the primer was similar. Example-If I do underbody work all of my primers used will be black so future rock chips don't stand out.

Second function if you can call it that, contrast with guidecoat, when working on highend jobs where the primer is blocked and blocked and blocked to perfection I just plain prefer light colored primers. Dark color guidecoats contrast well with light colored primers making imperfections stand out really well IMO. When I use dark colored primers I spray a light coat of light colored primer on for use as a guidecoat but it just doesn't stand out as well and I find myself looking very hard to see any imperfections. Sometimes I do my heavy blocking with light colored primer and do my final sanding on dark colored primer just for better coverage, etc.

I haven't seen any differences in fill or sandability related to color, they all seem to work the same.

Dupont's valueshade system is a fine example of what primer color can do for you in reguards to paint coverage. Bob

AC/DC 03-02-2005 09:33 PM

When he said "best covering" did he maybe mean that when you shoot color over it that you could acheive coverage faster/easier? Grey does seem to be the best color to paint over. Just a guess on my part.

cboy 03-02-2005 10:05 PM

Quote:

Originally Posted by AC/DC
When he said "best covering" did he maybe mean that when you shoot color over it that you could acheive coverage faster/easier? Grey does seem to be the best color to paint over. Just a guess on my part.

His argument was more about coverage and "fill for sanding" of the primer itself, not its effect on the top coat. I know this because we were discussing what I wanted for a top coat, which is a flat black which will appear to be black primer but, in fact, will be a finish coat to seal out moisture (like John Deere Blitz Black - although I'm going to use the Car Quest brand of flat black to achieve the goal). My assumption was that I would naturally use black primer to provide the best base for the flat black finish coat. And that's where he sprung the concept that there is a difference in the coverage and fill characteristics of the different color primers - regardless of the color of the top coat. And that gray was the best.

I really can't provide any of the specifics supporting his argument until I talk with him again. I was just interested to see if any of the experienced painters on the forum had ever heard of such a thing. And it doesn't appear they have.

AC/DC 03-02-2005 10:15 PM

OK then. Refer back to BarryK's first post, he's got it right. Color makes 0 difference on fill.

Baddbob has a good post too.

sevt_chevelle 03-02-2005 10:36 PM

Well PPG's NCP type primers come in three different colors a med green, gray and purple. If you look on the tech sheets for both products they have the same solids content and coverage per sq ft.

Color makes no difference on film build...Eric

MARTINSR 03-02-2005 10:50 PM

"Solids", "Filling", not only does color have nothing to do with it, a 2.1 urethane clear has more solids than your average urethane primer by FAR.

S-W has a tintable urethane primer. It is a milky color as Barry discribed. You add toners off the mixing bank to make one of 28 colors. After mixing, when you spray it, it STILL is quite transparent. But until some super high solid low VOC primers came out it had the most solids of any primer they sold. It is one of my favorite primers and fills like mad.

AC/DC 03-03-2005 09:20 PM

Could it be that he has a gray primer that is more expensive than his black primer? Just guessing, cause I can't figure out why he would tell you such things. I would now be careful in receiving advice from him. None of us a perfect and we all have opinions but what he said was strange.


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