Body Filler Recommendations ?

Here's another related question.

Finishing the welds down flush is a struggle for me. I'm using a die grinder with a 3" wheel and it's like working with a dental tool. I also have a nice angle grinder with a 4 1/2" wheel, but I don't think it's delicate enough for this application. I usually knock the tops of the welds off with the angle grinder, then do the delicate blending with the smaller tool.

What is the weapon of choice for finishing these welds ?

Also, do people finish the backside of the welds (opposite side) down flush too, even if they won't be seen after the interior is put back in ?

Tommy-
 
Thanks, I take it that the rust must be dealt with. This is the answer I thought I would get! OK I've cleaned it up, put on the filler. Then, I've primed it. It is not recommended that that I put filler over primer. However, Let's Say. there's still some scratches, pits, etc. Should I use red lead on it or a small dab of filler? So many questions! I apologize for them all, but I'm 60+ and never did this kind of work before. It's all new to me!
Terry





28ACoupe said:
Ok, Terry - if you can see light through the metal and it appears to be lacey, i.e. full of rust holes, get or make a patch panel and replace that area.

As for the pitted areas, it really kind of depends on where the area is and how badly pitted it is. I have never, in 20+ years of doing bodywork used any kind of an acid wash on bodywork. If you can get the piece to a media blaster, do so. If not, take your time with a wire brush and clean it up as best you can. Then shoot the whole area down with Rustmort to kill the remaining rust. This will turn the area black.

Use the filler directly on the metal rather than priming first.

Finally, as I told Tommy above, take your time and do it right the first time. Don't get in a hurry. Time spent at this stage will pay off bigtime in the end result.

If you can take digital pictures and email them to me, I can put them up here for you for others to comment on.
Click to expand...
 
no need for die grinders with cut off wheels or 4 and a half inch grinders with anything for that matter. your gonna make a mess in my opinion .tooo many rpms and your are going to thin the meatl out in a heartbeat . get a nice low rpm sander . i use an electric makita with a 5 inch 50 grit sanding disc.

seam seal the back of the welds and forget about them if you wont see them ever . if the back side is visible use extra care not to thin out the metal .

http://www.toolbarn.com/makita-gv5010.html
 
This is the most tedious part of this. Grinding the welds down to flush! I use a couple of 4 1/2" Grinders. One with a 2 1/2 worn out wheel that's very coarse. The other with a wheel that only cuts a small amount.
Then I use my 3"x 18" belt sander with a fairly coarse belt. I can only guess what it will finish, under paint, like. They look pretty good when I'm done. I'm always open to suggestions!
Terry






TommyCoupe said:
Here's another related question.

Finishing the welds down flush is a struggle for me. I'm using a die grinder with a 3" wheel and it's like working with a dental tool. I also have a nice angle grinder with a 4 1/2" wheel, but I don't think it's delicate enough for this application. I usually knock the tops of the welds off with the angle grinder, then do the delicate blending with the smaller tool.

What is the weapon of choice for finishing these welds ?

Also, do people finish the backside of the welds (opposite side) down flush too, even if they won't be seen after the interior is put back in ?

Tommy-
Click to expand...
 
Got it ! Thanks Pete! What is "Master Series"?

PetesPonies said:
Do not put filler over any rusted surfaces. remove as much rust as you can. Then cover with two coats Master Series. If the pits are deep, you could even use more. The following day, scuff the MS and then apply the filler. This will give you a permanent solution. Its the way I handle rough surfaces. Yes you can cover primer ( Epoxy is my choice ) with filler, but just use skim coats and make sure you scratch up the primer first for adhesion.
Click to expand...
 
A floppy sanding disc will allow for more area being thinned and less accuracy. You want to use a hard wheeled grinder, like a 4 1/2" variety. A 50 grit sanding disc is fine for finishing up the area, but trying to grind the weld from the start with it is doing it all wrong and causing exactly what you think you are stopping.

Terry, Master Series is a moisture cured primer. I have been using it in restoration work for 15-20 years now. You can apply with a brush or spray it. It is designed to go over less than perfect substructures. But can be used over good metal was well. This makes it valuable and easy to use. You put it over rusty metal that you cannot get all the rust and pits out. Scuff the next day as I suggested and cover any way you want.
 
With an angle grinder, I found that those flap sanding discs work well, and are less likely than a grinding wheel to dig into the surrounding metal. If the weld bead is on a crowned area, a file gives you the most control and least chance of damage. You can do 80% of the work with the flap disc and finish up with a file.

Doug
 
worked in hi-end body shop for years. Rage and UPol are the easiest and best fillers in my opinion. U need something that will sand easily, and they do. The cheapo fillers sand like a rock. UPol very reasonably priced. Should be using phosphoric acid over *all* bare metal.

Get all rust off metal, however u want, then scrub with steel wool soaked in phosphoric acid, and wipe with clean rag, repeat until no rust comes off on clean rag. Only the acid can get into the microscopic pits in the metal, where you can't go manually. Look up in metalurgy and chemistry books, it is called 'passivation', and use of phosphoric acid has been around since at least the '40s. Esp. needed for you northern and eastern boys where high humidity and salt have taken their toll. You can use filler or primer over this acid treatment no problem, in fact the acid is the best prep u can give the metal for paint/primer. Be sure to use enough so that when it dries, the metal has a sort of dull glavanized look to it. I'll sometimes play a torch over the wet surface to really get a good deep chemical reaction and bonding. The acid converts rust (Iron oxide, unstable) to Iron phosphate (stable and black in color; raw steel will have dull galv. look).

Epoxy primer is nice, but $$$$ and not essential. Have been using 2K filler-primers like Matrix brand and PPG brand for years no problems if metal is prepped correctly. When wiping or spritzing acid over metal if any gets on nearby plastic filler, no problem. Wear gloves but not a really strong acid at all. You can use primer over acid-treated (etched) metal, plastic filler, or sanded color. You can use plastic filler over etched metal or other sanded plastic filler. Evercoat glazing putty (2-part) in the teal and white container is the best and easiest to use glaze over plastic filler in my opinion. Some glazes dry too hard to sand easily and you end up digging into the surrounding plastic filler you just got done working on for hours

Use 50 grit 2" or 3" 3M Roloc sanding discs on a right angle air grinder for really controlled fine grinding of welds, you'll never go back. ORielly's has'em
 
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I have been using Kirker epoxy for a long time now. It is sandable and costs today about $100 for two sprayable gallons. That certainly is not expensive. Unless I need some polyester primer in an area, that epoxy is all I use, blocking and everything.

I also use lots of phosphoric acid.
 
Pete, You mention Master Series moisture cured primer, This sounds like a product I would like to try!!! Who makes it and where can it be purchased ?? I've been reading your posts with interest.
 
heres what one floppy sanding disc can do ...guess i did it all wrong

DSC05599.jpg



DSC05600.jpg


one slip with a 4 and a half inch grinder and you gotta mark in a panel that now needs addressed. and you are 3/4 of the way through the panel .
 
Flop, can't argue with your pics, but . . It's like sanding filler with 400 grit. Sure, you can sand with 400, it will take much longer. But that's not the real problem. The problem is the sand paper will not cut straight, it will follow the contours of the starting filler. Thats why you use course paper, it cuts straight. If anyone doesn't believe me, try it. Maybe 400 is crazy, but tryo flattening filler with some 220 or 180. No matter how straight and flat you try to get it, it won't happen. Well grinding metal is similar. I would rather get the bead down flat with a hard disc, then clean up with a course piece of paper.
Master Series Coatings is the name of the product. All you have to do is google. The silver primer is what I speak about. They have other products as most places do.
 
There's 1000 right ways to do it. The longer you're in the craft, the less willing you are to try things new as you've figured out what works for you.

That said, I'd like to dispell some myths. Filler over primer is not a big no-no. What is a no-no is THICK filler over primer. It will soften the primer base and raise a bullseye at the repair, and not right away. Maybe 3months after the job's done(!) and not worth the risk. You can fade it into primer without too much worry if you keep it thin or nearly transparent. If you like car shows on TV you see often how they make a birthday cake out of the projects. Frost the whole car in filler and carve out something that looks like car. Yeah right, except to those of us who've seen what they should really look like. Some INSIST you must do all body work over epoxy primer. No. Regular 2K is not too sensitive to the solvent soak unless the filler is real thick, but epoxy primer, even cured, will soften under anything over 1/16 of filler. I get a lot of "You're full of..." over that statement, but what have I got to lose or gain by sharing that info with somebody's car I could care less about? It happens. Not to some of you? Fine, go for it, but I won't. The rest is patience, talent, desire, and at least a decent knowledge of the products. In the end, bondo is bondo is bondo. It's a finishing aid rather than an answer. Some can sculpt some real pretty shape out of it, some refuse and tackle the metal. I'm in the latter, but I do use it for final surface quality. Dents and patches aren't meant to be frosted over unless you like redoing stuff. I've been a fan of USC Kromate Lite for a long time. Again, bondo's bondo and use what you like and fits your budget. I think Rage Gold is just marked up Kromate Lite, as both act the same under my sanding boards.

For finishing welds, look at like finishing anything else. Too far you cut through, not enough you leave highs. If you feel like it's too hard or taking too long, you probably don't do it for a living. It takes a long time to get this stuff right and make it last. No short cuts. If you want a short cut, buy a finished car and hope it was done right. Frustrated? Walk away and work on something else or just forget it all together until later. Many times when you go back to it you find it's better than you thought when you walked away. Just sayin...
 
The question about grinding the welds goes to what you are trying to do.

If you understand that every weld is shrink point then you know you have to do hammer on dolly work to correct the shrinkage. You first have to get the metal level. When I do MIG welding I first get the welds down close to level or you get distortion because the lumps throw off the hammer hits and deform the metal. I use a 60 grit flapper disk on my 4" Makita grinder. It takes down the high spots and stops at the flat metal. Flat metal only gets polished. You do both sides and then do your hammer on dolly work to get the metal close to correct. Then go in with a shrinking disk to finish leveling the metal. A few coats of filling primer and block sand with a coarser grit paper in an X pattern. I might use a bit of the thinner rage product for some of the minor deeper holes or the occasional deeper depression I did not fully fix. My gallon of Rage Gold has been sitting for a long time as I rarely use it.

I generally put epoxy on the panel before filler and look up the proper grit sandpaper to use before I apply the filler. To many guys use way too course a grit paper which give deeper scratch, but not enough per square inch. SPI recommends applying filler to the epoxy paint before the end of the recoat window for maximum adhesion.

Lots of ways to do this stuff. The key is to read what the manufacturer tells you to do cause they have done the science to figure out what works best. Word of mouth may seem simpler to do, but may not be a good way.
 
Highlander, I have never seen Kirker epoxy shrink as you say. You cannot group all epoxies the same. The most obvious difference is that most epoxies do not sand well. They are used for DTM only, then covered with 2K for blocking. Kirker is more of a reactive primer than most epoxies. It's recoat window is 24 hours, not 7 days like most. It builds well, sands well and is not effected by what you put on it. It actually "cures" .
 
I use Rage Gold for filler, but the process of welding in patch panels and grinding mig welds flat was problematic until I discovered EZ-grind mig wire. It is lower carbon than the normal types that are generally for structurally strong welds which means the weld usually harder than the panel steel. The hardness difference makes grinding difficult. The EZ-grind weld material is very near the same hardness as the panel. Hammers easier, files easier and makes getting the welds down to a common flat surface with the panel almost a joy.

I use .025 wire and always grind the excess weld bead down before hammering and usually re-heat the weld at the spot I'm hammering. I screw a nut on the end of my gas torch tip so I can quickly hang it on a simple post stand that has a U shaped notch.
 
I agree about the EZ grind, new to me this year, just can't get it locally, had to get it on-line. And in a non-cosmetic situation you'll find it will nicely weld slightly rusted steel, which regular 70,000 # wire will not do without tremendous aggravation and messy welds
 
Pete's, EZ grind is maybe 25% more than the plain ol S6. In the past I'd keep a small roll for sheet metal only and run the full size for everything else. That 25% pays for itself long before it's gone in time and quality. Also, thanks for the Kirker info. I'm 100% PPG. I gave up mixing products a long time ago, but will use HOK once in a while for specific requests. Heavier layers of filler have softened every epoxy it's ever been over, and while the edge may harden up when the solvents are gone from the fill, the epoxy below the main fill can remain soft for months. What happens next is the stuff moves around, shrinks or leaves trace evidence of plastics related failures under the paint. I'd rather seal my fillers with the epoxy to reduce or prevent solvent penetration. Just sayin...
 
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