sand paper

[br0nc0xrapt0r]

what grit sand paper would you guys recommend for sanding primer?

 

[firehawk]

I would use 220 if it is the last coat before paint. If you are using it as a guide coat to ensure the panels are straight then I would use 180 and then reprime and then 220.

Some people like to wet sand the primer before paint, but use nothing finer than 400. Some say 600 but you want something for the paint to adhere to.

Then there is the option of doing both 220 and then wet sand making sure not to sand through in either scenario, a little is ok but if you do you increase the risk of shrink lines or circles.

 

[TN1776]

I think the answer depends greatly on what kind of paint and primer you're using. I used a high-build polyester primer over top of my body work, wet-sanded with 400 then shot an epoxy primer then two coats of paint as soon as the epoxy flashed long enough to support the paint. I was told specifically NOT to sand epoxy primer at all.

Good luck.

 

[bax]

Your both wrong.;D Everyone does it different. TN1776 Epoxy primer /sealer does not need to be sanded if it is used as a final coat just before color. High build is made to be sanded.
Firehawk- 180 is too fine on high build and guide coats. Start with 80 grit and a long board file. You have to cut into the primer 180 will just run over the surface and you will not find your imperfections. It will take at least 3 to 4 primer coats to find and fill using primers. After you have got it straight prime one more time and start working with the finer paper. If you want to go to 400 that works. I like to spray a sealer coat just before color. The sealer coat will fill any small scratches you may have. When it goes off you are good for color. No need to sand the sealer coat.

 

[allenfahey]

There are alot of different ways to prep a vehicle but get the body straight with body filler before primer. Primer is used to fill small sand scratches. If you pile it on and on it will/can shrink in time. Bodywork should be finished off in 180. 3 coats of high build primer, block with 400-500, guide coat, Da it with an interface pad with 500-600, use a red Scotchbrite pad. Then you are ready for paint.
Or
Block primer with 320, guide coat, Da with 400 using an interface pad, red Scotchbrite, use sealer, then paint.
Or
Use spray polyester Evercoat Feather Fill G2 (same as bodyfiller but sprayable) block with 120 finish in 180, HS primer. Then follow one of the above steps.

 

[Pa PITT]

Well I sold Dupont paint for 30 year TO me Bax is closest to correct on his answer ...I'm not up on todays product ...everone gave a correct answer in it own time .....But the kind of primer your using is the the question each has it own window of time and grit of paper to fill the scratches .....check with the mfg and if the "kid behind the counter" can tell you correct use what the mfg recominds ....
A lot of todays primer needs to be recoated from 12 too 30 hours after it is sprayed .....OR you need to do something else ......
Many years ago the best one I ever use was a 2 part that covered 80 grit and you didn't sand it But you DID repaint it in a small window of time ....12 to 24 hours It smelled like pucky ''BONDO'' when sprayed it was so smooth ...feather rite .........I think was the name .....

 

[firehawk]

Coming from a bodyman thats been in the business for 15 years I like to think my mud work only needs one coat of primer or two if is going to be show quality.

Filler is cheaper than primer so make sure it is straight before you prime. 80 grit is for filler not primer, maybe 120 or 150 if you are not good at the filler work, then reprime as necessary.

I use evercoat metal glaze, a skim coat to blend the filler into the surround area then etch prime the bare metal then fill prime and block. And I agree with sealer before paint.

I am not knocking anyone for the way they do it, but I make my money on a commission basis, so I have to be fast and efficient and the quality has to be there also. The way I described it is probably the best way to do it, within reason. If anyone has a particular way they like to do, then for all means have at it.

I learn alot from this site and also try to help others and if someone is wrong or not well informed, then I think it is the responsibilty of the well informed to make corrections as necessary, or I would have made a few mistakes from what I have read in other posts. Just trying to help out and I greatly appreciate all the help I have received form the site and others.

 

[bax]

Like you said everyone has their own way. I am not a big fan of etching primer and I dont use it. I make mistakes even with this site's help.
It's part of the fun.

Bax

 

[allenfahey]

I too have been in the bodyshop industry for 15 years as a commision painter. There are alot of different ways to do this work but that doesn't mean it's correct. I know from classes I've taken and experience that you don't prime over anything other than 180 or finer. I did a test of my own a few years ago. I preped an old fender with 80 grit on some filler, 4 coats of primer, then proper prep and paint. Let in sit outside all summer in the sun. The primer had shrunk and I you could see the sand scratches. The normal everyday guy might not see or notice it but I could and a repair like that might come back to me. I too work commision and can't afford to redo it let alone the shop. That's why I also don't use cheap materials so I know it isn't the primers fault, it was Speis High Build primer.

If you have a question about a product ask for the spec sheet from the paint store. It will tell you what substrate to use it over, what to add to it, what ratio, what to sand it with, how long to dry, ect... If it doesn't answer your questions ask to speak to the jobbers tech guy, the one that does demo's for the jobber. Most have been to the paint companies paint school and they know the product the best.

PAPPITT you must have had a good group of guys in your store. The ones I deal with are like some of the guys in an Autozone

 

[bax]

Paint fight!!!
Not really. Sounds like we are all saying prety much the same thing. I just start with 80. It's not like I stay with 80 until the sealer coat. I work up the numbers. 80, 120, 180, 220, 320, 400 and even 600. Dont think for a second that all my primer build up is on the truck. Most of it is on the floor where it should be. I'm sorry but I use my high build as a final filler. If your still feathering in body work at this point your not even ready for paint your at 90 percent. That 10 percent will double the time you have in the job. You make it perfect with primer not glaze or a skim coat of anything. I'm a carpenter I don't do this to make a living, I don't even do it as a hobby or a side job. Body work sucks but my labor is free and I am not trying to make a living doing it. I would starve. It's just my way and it works for me. After reading this please dont think I am going off an anyone, I am not. So to answer the origional guestion: Use all of them.
Peace and love to all.

Bax