Question on body preparation

[Deleted User]

I am getting into an area now that I am unfamiliar with. First off, I have sanded the body down to bare metal and have applied one coat of epoxy primer. THe question is should I give the primer a light sanding and then apply another coat of primer or is that overkill? When I start sanding it, be it the first or second coat of primer, what grit paper do I start with and in what increments do I use finer and finer paper. What about wet sanding?



Thanks, Doug

bellbigdawg

you only have a 24 hour window to recoat epoxy primer. after that, you have to sand it with 220 grit. pull the MLS sheets off the product web site for instructions for product use. get a how to paint book if you have any more questions. this is not an area that beginers have alot of luck!!

Kdancy

epoxy primers that I have used, have a 7 day re-coat window.

here are a couple of good post's

http://www.autobodystore.com/forum/showthread.php?t=1214



http://www.autobodystore.com/forum/showthread.php?t=8609&highlight=epoxy+primer+re-coat+window

RL Chilton

Doug-



You've opened up a can of worms with your question, and here is why:



Painting an automobile CORRECTLY is really an art form. That simply means that llike skinning a cat, there are literally a jillion different ways to go about it, and one man's procedure will certainly differ from another's. I said "correctly", with the intent that what you are trying to do is a quality paint job that 1), will last, 2), you will be proud of.



There are those that will spray on a coat of Scotch-Gard over existing paint and shoot a new color on top of it, ala Earl Scheib's, "We'll paint your car for $99.95!!". I'm going to assume that you are on the other end of the spectrum than that.



Firstly, is all your bodywork completed? Assuming that is done, 2-3 coats of Epoxy Primer is usually employed to make sure you cover every square inch of bare metal. Follow the directions on the can, but usually 6-8 hours of drying time and you'll be ready for the "block sanding", which is the stage I think you are actually asking about.



After the epoxy primer has cured (usually 8 hours or so), the rage these days is to shoot on 2 or 3 coats of high build primer. If you decide to go this route, especially on older cars with a lot of fine crevices and body lines, try not to shoot too much into the corners, like the speedline on a stepdown. You'll lose the nice crisp lines down in those areas. And stay off of the outside corners as well, you sand right through your primer in no time.



Next, shoot on a guide coat of cheap paint from an aerosol can. You'll be sanding all this off, anyway. The purpose is to show you where your final highs and lows are located.



After the high build primer has cured, put 320 or 400 grit sandpaper (depending on how smooth your surface is) into a bucket of water with a few drops of liquid soap. Let them get good and soft. USE SANDING BLOCKS. The longer the better.



Then wet the surface to be sanded. Use a hose, a big sponge, whatever. Don't let the sandpaper clog and start making deep grooves in your work. Change it often. As you find low spots, tap them out from the back. If you work in an "X" or "+" fashion, you'll be able to see where exactly you are smoothing out the surface.



As you break through some spots where bare metal shows, they have to be primed and sanded again. You can work your way to 400 or 500 grit for a really smooth surface. Make sure all metal is covered in primer when finished.



I'll probably catch some flack just for posting this, but remember, it's not rocket science. The whole purpose of what you are doing is to make a surface that is as smooth and flat as possible for your final paint coats. This is but ONE way to go about it. The other thing to remember is, the better a job you do right now, the better your paint job will come out. This step is the most important of the whole thing.

Kdancy

RL Chilton wrote:

Doug-

After the high build primer has cured, put 320 or 400 grit sandpaper (depending on how smooth your surface is) into a bucket of water with a few drops of liquid soap. Let them get good and soft. USE SANDING BLOCKS. The longer the better.

That is one thing I used to do, but no more. The coarser the paper, the less "riding" it will do when going over waves in the sheet metal. Thus, I will start my block work with 120 to 220 grit on a long board and block until I am satisfied the waves are out. I will only use the 400 to get the final prep finish prior to paint.



Another good info post on this -- I have gotten a lot of paint tips from these guys-

http://www.autobodystore.com/forum/showthread.php?t=13005&highlight=Blocking+spray+filler

RL Chilton

Kdancy wrote:

That is one thing I used to do, but no more. The coarser the paper, the less "riding" it will do when going over waves in the sheet metal. Thus, I will start my block work with 120 to 220 grit on a long board and block until I am satisfied the waves are out. I will only use the 400 to get the final prep finish prior to paint.



Another good info post on this -- I have gotten a lot of paint tips from these guys-

http://www.autobodystore.com/forum/showthread.php?t=13005&highlight=Blocking+spray+filler

That's what I meant by "depending on how smooth your surface is". I'm assuming, of course, he's already past this stage.

Geoff

I can paint a car in a day. But it takes me a month to prepare the surface!

Geoff.