General priming question....

[trapin]

I'm nearing the phase in my project when I have finished the initial filler application part and am ready to shoot the car in primer. My question is...........I wanna kinda stack this primer......right? I mean...if I'm going to be doing any blocking, I want there to be enough build of primer so as not to burn through down to the metal. I was thinking of doing about 4 coats of primer per panel. So what I want to know is...do I lay on a coat of primer, let it flash, and then do a 2nd and then repeat? Or....do you have to wait for that first coat to completely dry before adding a 2nd? I've heard of a problem that can arise called solvent stacking or something to that effect if you do 2 successive coats of primer. I'm not using a high build primer. Any direction you can give me would be greatly appreciated. Thanks. :3gears:

[68protouring454]

tony, you are not using a high build primer?? why not?? most all urethane primers are high build, to the tune of 7-9 mils, you do not want to use a epoxy primer, just etch prime bare metal then go right into urethane primer, 3-4 coats would be good, yes let each panel flash hand slick before topcoating, handslick is not touching in a spot, its having the ability to drag hand across panel with latex glove on and not stick, thus making it very important to be flashed off well or you will put deep marks in primer , you will have nop issues with solvent pop or anything, i however would let it sit 2-3 days and have it in the sun if its sunny
let us know products and part numbers you are using
jake

[BuddyP]

what do you guys mean by "flash"?

[68protouring454]

means the paint/primer is not cured but the bulk of the solvents have dried, and it is hand slick, meaning with a latex glove you can pull hand across work, if you do not think you can do that do not apply another coat, this applies with everything, except do not touch clear, just in an unseen area, this is why alot of at home paint jobs end up with runs cause there is no air flow and one side of the car flashes alot quicker than the other, i always tack cloth inbetween all coat of sealer and basecoat
gotta be flashed off or the tack cloth will screw the base up
jake

[redss86]

tony, you are not using a high build primer?? why not?? most all urethane primers are high build, to the tune of 7-9 mils, you do not want to use a epoxy primer, just etch prime bare metal then go right into urethane primer, 3-4 coats would be good, yes let each panel flash hand slick before topcoating, handslick is not touching in a spot, its having the ability to drag hand across panel with latex glove on and not stick, thus making it very important to be flashed off well or you will put deep marks in primer , you will have nop issues with solvent pop or anything, i however would let it sit 2-3 days and have it in the sun if its sunny
let us know products and part numbers you are using
jake

just wandering why you say you don't want to use an epoxy primer?

[427v8]

Would you consider k36 to be a high build primer??

[BRIAN]

If you are doing home job try NCP line from PPG. It is both etch and high build in one. Can go right over bare metal and sticks like you wouldn't believe,sands nice, and has reasonably high build up. Stinks worse than anything but simplifies having to buy so many different products. If you have serious waves use a high build poly primer instead.

[68protouring454]

because there is no sense to use epoxy as he has done all body work and sanded whole car, plus his car has been dipped and ecoated, i would etch bare metal, the go right into 3-4 coats of urethane primer which is high build and has to b sanded before topcoating, no sense not using a high build urethane as it will get rid of small flaws and it does not have to be sealed, unless it is not finished in high enough grit.
i have not used what brian is talking about but i would look into it, as it sounds good and plus tonys cars has been dipped
jake

[Boyd]

just wandering why you say you don't want to use an epoxy primer?

.....you ever try to block sand epoxy? I had a buddy that wanted to paint his son's truck. He calls me one day and says he can't get the primer to block very well. So I go over to his house, he sprayed the entire truck with 3 coats of DP90!. After laughin' my a$$ off for a few minutes, I helped him block it. It took us a whole weekend to do.

[trapin]

I thought flash times varied from 15 minutes to about half an hour. I never heard of having to wait 2-3 days to do the 2nd and 3rd coats. Isn't it supposed to still have some tack to it to apply the additonal coats? Or did I misunderstand you?

As far as the primer I'm using, last year I purchased Transstar 2K Acrylic Urethane Primer. The can sat in the garage all winter even when the temperatures dipped below freezing. Should I go with a different primer? Is it still good to use?

Also as stated above, the car is primarily all in e-coat but there are a few spots where I burned through the e-coat while scuffing it last year. Do I have to etch those spots or can I get away with the regular high build primer?

Also...I will not be painting this car in my garage, I have rented a paint booth for July 16th for the entire day. So I've got a lot of work ahead of me to get ready.

[ProdigyCustoms]

I hate epoxy for all the reasons previously stated. Sands like concrete. Epoxy sucks. Far as primer, Sherwin Williams has a new urethane primer in their lower cost Select line that can go over bare metal, e coat, primer, paint, what have you. I used it on Wallys 62 as he was on a budget, and I was impressed. Seemed to really stain the metal meaning it bite in strong, built nice, and sanded very well without clog after a overnight dry.
On my high dollar paint jobs, I will still use the higher dollar Sherwin Williams Ultra Fill over GBP self etching zinc primer just because i have many years good experiance.

[Boyd]

.... you should not wait 2-3 days between coats. The coats only need to "flash" between each additional coat. If you're having a hard time understanding flash, take a test panel and spray a small section. Make sure there is plenty of light. When you first apply the primer, it will look very wet and will have a semi-gloss look to it. Now (under the light) you can watch as the gloss begins to go away and the primer takes on a flat or dull appearance. This means most of the solvents in the paint are evaporating. This is a good thing. Unless you're spraying in a very humid or cool environment, it shouldn't take anymore than 5-10 minutes for each coat to "flash". Before the next coat goes on , take a gloved hand and lightly rub it across the coat you just laid down (after it flashes, of course). It should feel smooth and cool to the touch, but there should be no primer on your glove. If there is, it's still too wet and needs more flash time. Now, after spraying the car with the desired # of coats (3 sounds fine for the Trans-Star) let it sit for 2-3 days before you block it. This will allow the primer to "shrink". Basically you are allowing the solvent that did not "flash" off when you first sprayed the car to evaporate. Allowing the primer to shrink will help prevent sanding scratches from showing through in the basecoat.

[trapin]

So the primer that I bought is OK to use....even though it sat out in freezing weather all winter?

[Boyd]

trapin - it should be just fine, except for the actual paint booth itself, most paint shops (most of the ones I've worked at anyway) aren't climate controlled. If you have a local paint supplier, just take the gallon to them and ask if they'll shake it for you. Even if you didn't buy the primer from them, they should do it. Maybe buy a couple rolls of masking tape or something....

[68protouring454]

i meant to say if primer is not baked wait 2-3 days before block sanding it.and get it in sun if possible, to get the solvents out and get it to shrink all up.
i laid out when to wait for next coat, when its hand slick just as boyd also laid out in his advice, i would not fret over having primer shook, just stir for awhile till its all evenly mixed and not sludge on the bottom

i would not use transstar anything, if going that cheap, get som mar hyde ultimate 2k primer, but again being a cheap urethane primer i would spray 3-4 coats, handslick in between then let sit 2-3 days before touching.
jake