Auto painters- I got a question!
 

I'm about to purchace a package of "Dura Block" sanding blocks to use to prep my truck and a few other cars, I plan to sand the curent paint and primer it before repaint and wondered what order of sandpaper grits to use, I've done similar painting in bathrooms and have a fairly good idea of the automotive prep process, but never knew what order to use sandpaper in!

Also, any recomendations on good books regarding painting cars? I'm sure it wouldn't hurt to see what tricks I don't yet know :)

books on painting cars are all very old i would try the internet for more curent info... and last time i worked in a body shop we sanded the car with 220 untill the clear coat isnt shiny any more then sealed and painted it (you can use the orginal paint as a primer coat... unless there already is a few coats on it) but its been a few years so im not 100% on my info

220 before basecoat? Ouch! You'll see every bit of it

Depends all on if you're doing a small area or a complete job...but genrally youll want everything finished off with 600 grit, wet sanded by hand with a block before paint. Here's the breakdown:

36 grit- Use this to rough up the areas you'll be applying body filler.
80 grit-This can also be used to rough up an are before applying either glaze or thick filler. Also, This is used for rough shaping of the first layer or two of bondo. Work your way to
120 grit-Before applying body glaze (Acrylic glaze, very fine body filler)
220 grit- Use this to shape the glaze
320- (optional) use this to remove sanding scratches from 220

Primer

400 grit- This is going to be your new best friend. Do almost all your sanding with this
600 grit- Finish the whole job off with this, because believe it or not, you'll actally see 400 grit sanding scratches under the basecoat. 600 grit is basicly the point at which paint will suscessfully fill the scratches, even after it has shrunk back. But dont sand it any finer than this, otherwise the basecoat will have a tough time sticking
1500 grit- Use this to get a blend panel ready. A blend panel is a panel adjacent to the one getting painted, which recieves a little bit of the paint at the edge meeting the panel its getting blended to (I.E., If Im painting my door, ill take the fender and the rear door for blend panels, and dust a little of my base coat onto the edges of the fender and rear door, then clearcoat the whole thing)
2000 grit- This is used after the clearcoat has dried. Completely by hand, lighty rub it on small dirt specs and other imperfections and buff it back. Or, use a block, and wet sand the whole job, and buff it back. This will create a shine that you probly havent seen since laquer paint was commonplace

A few notes here:

for prepping an area that doesnt need body filler or primer, its the same as primer. Prior to primer, the area around the bodywork should be sanded with 400 grit

typically, Ill go over the panels being painted with a dual action sander to remove all the chips, scratches, and to flatten the old paint / clearcoat.Afterwords the bodywork gets done to the dings and dents. tape it up for primer, and lay on some good heavy coats. (Two on the body work and one over the whole area, making a solid three coats) Then Ill wetsand the primer by hand. *tip: Dust on a layer of black spray paint to use as a guide coat. While sanding, it will show al the high and low spots, and every little bit of orange peel* After the primer is completely smooth (It should be the smoothest thing you've felt in your life right now) Wet sand the entire panel with 600. At this point, set up your blend panels. Knock them flat with 1500.(Completely flat, no orange peel or shiny spots!) There are scuff pads out there, and a toothpaste like product that will work alot faster and easier, but its likely you wont be able to find it at your local hardware store.

A litte tip on sanding stuff: Hold the sander as flat as possible. Sure, you can dig a chip out real fast by holding it at an angle and cutting it, but if you feel it afterword, it makes a crater. Also the same goes for any kind of blocking by hand. Hold the block as flat as you can, and use long, straight strokes. I prefer to use a power sander of some sorts only for rough bodywork shaping (See: up to 120 grit) and for getting panels ready for prime / removing chips (400 grit) All acrylic glaze gets hand blocked with 120-320 dry, on a sanding block, and all primer sanding, panel sanding, blend panel sanding, and getting buffed sanding are done wet, with a hard block. A soft block is used only for channels, grooves, and difficult curves

Um...I think That more or less gets it for now. Need to know anything more, feel free to ask

Slight edit of the body filler part. You can use 80 to rough shape heavy filler, or to score an area for glaze. you can use 120 to shape heavy filler. For shaping a glaze, I reccomend using 220 and finishing it off with 320

Thanks Eric, that should hold me over for a bit! I'm going after the 9 piece kit, but found a little better deal on Ebay-

http://www.tcpglobal.com/autobodydepot/durablock.aspx

this will be the entire truck, so I don't get to learn about blending this time :) and I can work up my courage for a nicer car :p

NOTHING beats EXPERIENCE!! Don't start w a CAR!! try a bicycle, make little mistakes, next try a motorcycle, and make bigger mistakes. I am up to BUSSES now, and still making mistakes!

If all the DUPONT product I have sprayed were in one truck, there would be TWO 54 footers hooked together. The CHANGES in the tech THIS year alone makes me a RANK Amature!

Go online, start small, go BIG!!