I have the body of my panel stripped to bare metal , I used 80 grit. on the areas that need to be filled should I scuff with a courser grit, I'm going to be using All Metal filler product that says to apply to bare metal but don't specify grit. and is the 80 grit course enough for epoxy or to course.

John

 

The bodymen I have talked to say that 80 grit gives enough "tooth" for the filler to grip.

I'm not familiar with the "all metal filler product" you mention, bit I can imagine that sanding it to shape will be a tough job. I used Evercoat Extreme Rage body filler and love it. Much fewer pin holes (bubbles), etc. Sands out very nice.

I also used 80 grit to get to shape, then 180 to finish for primer.

 

Scratches may show through the epoxy primer after 80 grit but most will follow the epoxy with 2k high build primer after all the body work is finished, then block sand and paint. The scratches showing in the first coat of epoxy want matter if this is your plan.

 

I vote for the Rage filler, but All-metal is a good brand as well. Rage works well, sands well, prefered by many of the top body shops. It does set up rather quickly tho so be sure not to mix a large amount and work quickly, quit when it first starts getting cottage cheesy and discard any unused material as it will set hard withing a minute or two after that point. 80 grit is fine for tooth for filler, but wipe the area down with lacquer thinner until the paper towel/rag shows clean. Sanding dust sticks well to the metal but keeps the filler from sticking. Same with skin oil. Avoid touching the panel with bare hands while working on it, or if you do wash it down again with mineral spirits between applications of filler or paint.
Sanding scratches, small dings and waves can be filled with a catalized polyester glazing putty such as Euro-soft (this is the putty you see them using in large quantities on the TV shows where they coat the entire panel before block sanding it)
Some people are now recommending rolling on the primer coats with a disposable foam roller over spraying it on, especially if you are using a high build primer.

 

Now that's a great idea! Sure seems an easier way to do it. I could get the primer on and block sand, then clean up before dedicating the garage to painting the base/finish coats. Cool, man.

Do you know how much time you have between mixing the primer and it setting up?

Are there any water-based primers that are high-build?

 

The biggest mistake novices make is not carrying the filler out far enough and not using a large enough sanding board. Carry the filler out at least twice the size of the dent, and use the longest sanding board that you can. I have used boards as long as 3' for large panels like hoods and roofs, if you don't have one buy yourself an 18" "longboard" sander and self stick paper for it. Unlike sanding wood, you hold the board parallel to the panel's long dimension, but move it in diagonal strokes, first in one direction, and then in the opposite direction. Quit sanding at the first sign of touching metal. Refill any low spots, don't try to sand down around them to eliminate them you'll just end up making waves. If you have one spot of bare metal show up in the middle of the filler, tap it down slightly and refill.

 

I haven't seen much in water based primers at all, AFAIK all the catalized primers are solvent based.
In the current issue of Hot Rod they painted a Falcon with rolled on hardware store Rustoleum Enamel just to see if it could be done! Cost a total of 95.00 but was very labor intensive requiring 6-8 heavily thinned coats and several sandings between coats, as well as color sanding and buffing, (took a little more than a week with drying time between coats) but they said it was a good 5' paintjob, better than you might get from one of the quicky paint places for 3x as much.

 

Just outta curiosity....It it better to do a coat of etching primer before the filler? Can you use etching primer over filler and old paint? There seem to many diferent thoughts on the order of the process. Is it dependant on the individual or the product.

 

Body fillers should go on bare metal only and sealed as soon as possible after. Glazing putty can be applied thinly over an epoxy primer. Etching primer is normally used on bare metal, if you use epoxy primer, no etching primer is required.

 

So what you are indicating is that ther are two distinct options.

1- Etching primer for the bare metal surfaces and epoxy primer or standard non etching for the areas in paint.
2- Epoxy primer on everything after metal prep has been done.

Metal prep should be done before scuffing and proior to filler and filler is sealed by the epoxy primer...Is this correct?

One more quick tid bit...can a high build primer be used on top of an epoxy primer?

 

high-build primer IS (Polyesther) epoxy primer.

I am doing my own bodywork, and learning as I go with info and some help from a painter friend of mine. The work is going pretty slow because I'm only able to put weekends on the job. I apply filler to bare metal, as Ax said, then cover the area in the (rattle can) etching primer to give it some flash rust protection. This also allows me to get a good look at the surface to see if I missed anything. If I discover that the area is still wavy, I sand the etching primer away and refill and resand it. The filler doesn't stick very well to the etching primer, but the epoxy primer will stick to it fine. The epoxy primer will go over everything once I'm ready to block sand the final surfaces.

If you plan to do it a little at a time, I would also recommend that you sand an area to bare metal only when you are ready to fill it. Sanding paint off the whole truck before you are ready allows it to flash rust.

I believe the BEST method (if possible) is the media blast everything and then shoot it in epoxy primer. Everything is then protected against rust and you have all the time you need to do the job. You can do the bodywork right over the (scuffed) epoxy primer, which works well since the filler is also a type of epoxy. If welding repairs are necessary, sand the primer away well around the area, repair it, fill it, then reprime it.

I found this website very helpful: http://www.autobody101.com/

 

But not all epoxy primers are high build. High build primers are like sprayable spot glaze putty and are used to give thickness for final blocking without having to spray many coats of standard build. If you don't want a high buildup for sanding (like over existing paint) then use a standard build. If you go with a high build, you will need a large cap and needle like a 2.0, and a high enough air volume to not run out of air in the middle of the job or to start spitting. If you use a one part primer, be aware that it is not waterproof and should not be used if the truck will be exposed to weather for some time before final paint. Either spray a sealer coat over the single part primer or use epoxy primer. I'm not partial to mixing a lot of different products even if from the same manufacturer. I used rattle can primer/sealer on Gracie's dashboard because I knew it would be a time before I painted it, but it will be sanded off before priming in epoxy and painting. Most of the paint manufacturers have extensive technical info on their web site for their products both for application and compatability. I first pick my final brand and type paint, then use whatever under products that manufacturer recommends.

 

I just got back in and didn't expect so many replies this early, thanks. The all metal filler that I have says to apply on bare metal, that I have but don't have it completly bare, I still have to sand blast around the door frames and wind shield areas but the weather is not cooperating with me thunder storms repeatedly. So the epoxy primer is on hold until I can finish stripping it. I have some long boards on order through Eastwoods that should be arriving shortly. Now back to what has been discussed, I was under the impression that you applied epoxy then a high build primer after that,to which you could then apply the polyester filler to block sand. I just hope I'm not getting in over my head. One other thing I was wondering about was the stain marks left in the metal from scratches, they are not blistered or pin holes just rust stains will the epoxy primer seal these with out worry of them blistering later down the road.

John

 

from what I know, the filler is put on bare metal, then sanded with 36 and 80 grit as per Ax's directions, and then apply the primer and sand with 320-400 grit sand paper. A misting with a guide coat (black) helps in the final sanding process. But, everything I've used has been PPG. K-36 primer/surfacer for "high build". This mostly for spot repairs.

 

Is any one familiar with a epoxy primer brand name Endura ( ep-fd epoxy primer ) it's a two part primer.