So I have most of my hammering and welding out of the way. The only piece of body actually on the frame right now is the cab. As I finish making each piece look the way it was supposed to look, i've been covering up the bare metal with rattle can primer. I've managed to rebuild all four fenders, the front piece with the 'FORD' letters on it, and the doors. The bottom front valance is the last one that needs more rust cut out, metal welded in and hammered back into shape.
My question for you guys is whether or not I should go ahead and primer/fill/color everything and then assemble them or would it be better to go ahead and put it all back on the truck and then paint it?
I have the basic steps down to this:
1) a coat of epoxy primer
2) a coat of high build primer
3) body filler work
4) another coat of epoxy primer
5) color
I have all the primer and filler supplies. I've been waiting to finish the rest of the bodywork before I order the color.
Mike

 

Just my humble opinion as I am no where above amateur status nor do I have a good place to paint. I find it impossible to mask some areas so I like to paint them before assembly. Doors come to mind. When I paint prior to assembly I always wind up with a chip, scratch or two or more. A lot depends on the final paint. I've read it is not always easy to get an even color when you paint panels and then assemble. I am sure those with expert status as painter, bodyfolks will chime in. Good luck and pictures.

 

You're gonna get a lot of different opinions on this one. Rattle can primer can cause a problem in that it doesn't bond well with newer paint compositions. I would think that the epoxy primer over the rattle can primer should be OK because the epoxy will stick and seal over just about anything. The high build primer should be an urethane primer because it builds faster and is easier to sand than epoxy. I can't see any reason to epoxy over the urethane, you'll just have to sand again. Go ahead and paint over the urethane after sanding. As far as painting the whole truck at once, that's how mine was done, but I would recommend painting one part at a time and assembling after. It's much more professional and there just are places you won't be able to get to at the correct angle to get a good finish. Good luck and if you don't already have one, use the correct resporator. Post pics

 

You can save a lot of money and time if you not go with your first round of high build primer before your filler work. It's not necessary. I've always done my filler work on bare metal, because that's the way I was taught and I live in a very low humidity area where flash rust isn't a concern. Some guys like to lay down epoxy primer first, and that's acceptable, too. Even though materials have improved and are more compatible than before, filler still shouldn't be put over any more primer than absolutely necessary. It makes for too many layers and areas for things to fail later down the road. I would recommend having all your filler work as perfect as possible before doing any heavy priming.

Whether you paint before or after assembly is up to you and your patience and skill level. I like painting everything apart and putting it together last. It makes for a much nicer and cleaner job, imo. Others will be afraid of scratching something on assembly, and that's their choice. Either way, the end result will be the same. Hopefully.

Oh, and get all that rattle can primer off your parts before doing any kind of professional and final finish work. That is a recipe for disaster.

 

I read your post again.... do the the body filler (bondo) before the urethane primer. Rough up the area you're gonna fill for good adhesion.

 

Couple of questions first:

- what type of "rattle can" primer are you using? If it's not a DTM (direct to metal) product then you will need to sand it off and apply a good DTM primer. This is your bond to the metal, no place to use the wrong primer.
- what type pf paint are you using for your finish coat? Solid color or metallic, single stage or BC/CC.

I always paint each panel seperately and then assemble after...this ensures that you get a good coat of paint on all mating surfaces. No shadows in the corners. If using a BC/CC it also makes it much easier to get the corners buffed out before assembly.

I use SEM Metalock DTM primer. It has superior adhesion, is very durable, and sands well. I would not recommend any polyurethane primers, they were better than the old lacquer-based primers but they don't hold a candle to the newer 2K products available today.

Filler application...old skool technique was to take everything down to bare metal before appying filler. This was necessary because the early fillers would not bond well to paint. The current line of fillers work very well over primer and they recommend that the metal be primered BEFORE applying the filler. The rationale behind primering first is that it will better isolate the metal from moisture/oxygen that may get through or under the filler. You can make up your own mind about this.

Pre-paint prep: if you use SEM or other DTM 2K primers you can thin the primer out to the max recommended and use it as a sealer. The sealer can be sprayed over the entire piece to be painted and then the final color sprayed over the sealer (usually after a short "flash" period). The sealer will hold out any issues with incompatibility between your color coat and the paints on the panel.

 

Thanks guys. that was quick.
Here's a little more background. A 4X8' utility trailer is my sole experience with automotive paint. I have srayed quite a few AGM-88 harm missiles though, so I at least know how the guns work and have good respirators.
The steps I mentioned came from the owner of the paint store in Boise that I'm getting my supplies from and he came highly recommended. We talked for awhile about my experience and my goals and I went by his advice.
The rattle can primer was used mainly because it's just taken me so long to finish the parts. I've learned to weld and do hammer work on this truck. I do want a high quality, long lasting paint job. I finished my first fender last spring.
Space is also becoming an issue. I'm running out of room to put parts that I've already pounded the dents out of.
I'm leaning towards laying down the primer and doing the filler work separately and then assembling before the color. That will save the first scratches for the dog. I'm not makeing a show truck. When I need a yard of gravel, it's going in the bed.

 

Glad to read that.

 

I would never use any rattle-can primer on a quality build of any type, unless you planned on stripping it back down to bare metal before spraying on an epoxy primer. I would only use a 2-part epoxy primer on any bare metal, then do the filler work. Once you have all of the filler and body work completed, you could spray a build primer on and do all of your sanding. Once that is done, then I would spray another coat of epoxy primer over everything to seal it. If you want to do a good, quality paint job, and you want it to last a good long time, the don't skimp on the prep work. The paint will only hold up as long as everything underneath it. Good luck with your project.

P.S. Here is a forum that I belong to, they are a full of quality knowledge (much like this site). SPI User Forums

 

Here's my opinion for what it's worth. Since I am not a pro painter and the materials are constantly changing mostly due to changing regulations, and the price is starting to reach the stratosphere, I start with choosing the product manufacturer by the finished color and desired finish, then use that manufacturer's recommended prep materials and methodology either from their literature or sales rep. That way I am assured of compatability, and if anything goes wrong I can get support. If you mix brands and or materials, the paint manufacturer will just pass the buck if there's a problem. Remember the guy behind the counter at a supply house that is not brand specific, no matter how well intended, is giving you second or third hand advice, he himself is not swinging a spray gun. I like to do my initial priming dissasembled so I can get all surfaces, do my hi build and or surfacer filler, reprime/seal, color spray the door frames, engine compartment, under fenders etc, loosely hang the doors, fenders, etc,then spray the finish coat, especially if painting something like heavy metallics, translucents, transparents, special effects clearcoats etc. If you paint these finishes on separate parts it will be very difficult to get a match. Just painting the body sides with the body sitting vertcal and painting the fenders laying horizontal can change the appearance and match. One way to reduce shadowing is to have your primer tinted towards the top color.

 

That is very good advice as well, Ax.

 

Charlie- I missed your post before my last reply. I'll have to check the can stuff this afternoon. I know its rustoleum auto primer, but I'll double check to make sure. I get lost with the uerathane/acrylic/whatever terms. I know I'm not doing a clear coat. It will be paint I need to use buffing compound on after the final coat.
AX- I completely understand the 'salesman' reasoning. One of reasons this person comes so well recommended is because he is a painter. The way I understand it is that he finally got fed up with people wanting $7000 paint jobs on their hot rods but didn't want to pay more than a $1000 for it. He just decided to supply other painters in the area instead.
During my talk with him I had a chip of powerdercoating that I had put on my wheels. It is a cream color that I wanted to match on the hood/doors/cab/bedsides. The front end and fenders will be a dark red/maroon. The cream actually turned out to be a range rover color that he will get from PPG. the maroon we picked out is also PPG. It was from there that he did exactly as you suggested and picked out the primer/filler products based on the final paint.
Sounds like I might have added a bit more work for myself with the rattle can. I will check this afternoon and see it is the DTM that Charlie talked about. If I have to sand it off, so be it. I'm just glad I don't have to weld anymore on the fenders. I replaced about 30% of the backside of the cab to make it solid and that seemed like child's play compared to fixing the fenders!

 

A lot of bodymen and custom painters use rattle can primer as a guide coat when block sanding the surfacer putty and or primer. Use a contrasting color rattlecan and apply a light dust coat on the panel. Sand the panel with a longboard or long foam sanding block and 320 stearate coated longboard paper (looks like it has wood grain pattern in dust on it, use either sticky back paper or sandpaper spray glue to attach nice and flat) Hold the board with both hands horizontal to the ground lightly against the panel, using only enough pressure to keep it in flat contact. Keep the block horizontal but move the board with 45* strokes bottom left to upper right until you have sanded the entire panel. Now still holding the board horizontal sand with strokes at 45* from bottom right to top left. Stop when you have resanded the entire panel. Now wipe the panel with a clean rag dampened in prepsol. and dry with another clean cloth. Now examine the panel. It should have a very fine crosshatch sanding pattern on it. Under ideal conditions the primer guide coat (or your rattle can primer coat) should be sanded clean off without sanding the under primer thru to bare metal. More likely you will see clouds of the guide coat remaining in the low spots. DON'T sand off by concentrating on that area or by applying more pressure! You will just make flat spots and hollows. Mix up a batch of surfacer putty (I like Eurosoft) and apply over any and every "cloud", keeping it thin and as smooth and feathered as you can. After it cures, re-block the surfacer putty with 120 grit paper then dust on another guide coat of rattle can and re-block the entire panel with the 320 as before. Continue this process, the clouds should become fewer and smaller each time. When the guide coat sands off completely without hitting any bare metal, give the panel it's final prime coat, you have a flat and smooth panel!
Never rush the final surface prep, the paint job will only be as good as the surface under it. A good painter may spend a week or more blocking the vehicle.

 

Thanks Ax. I really wish I could just tear down the engine and rebuild it about 100 times and then the whole truck would be done. I'd enjoy that.
I checked, and the rattle can stuff I've been using is compatible with the epoxy primer I have. I'll be able to start sanding on everything in about two more days. I just won't be able to start on the bed yet. That'll probably be the last thing I work on.
I have some black rattle can primer also. I'll use that like you explained with the filler.
Mike

 

My suggestion and the way I plan on doing the Final color on my truck is paint the underside and inside of everything, assemble, and the paint the outer panels of the trunk. I feel this will reduce my paint chips and also help with the final color as I have heard if its not mixed the same or entirely you may have different shades across the body.