I have welded some panels on my truck and I would like to know if I should use fiberglass first then bodyfiller or can i just use bodyfiller and if i only use the body filler will it crack
Fiberglass is the wrong way. Make sure the panels are fully welded in and ground. That means no pinholes at all! Seal it from the backside and use some filler on the front to smooth out the joint. It won't crack for a long time as long as you use it properly.
Hey Bro! Now remember this is just my opinion. I have worked with fiberglass and the application was on a fiberglass boats. I have always stayed with fiberglass to fiberglass. I have used bondo on metal with good success and it really has not cracked. Make sure to buy a good quality bondo not the k-mart stuff. although it will work in a pinch I don't want to offend anybody. Shawn
Filler on the metal is fine. no pinholes in your welds and get the metal as close as you can (hammer and dolly) dont put 1 inch of mud on it. the fiberglass stuff is the hillbilly way for fixing things that should have been replaced.
You should not need much filler if you hammer and dolly it and get it close before applying filler.You don't want the filler to be thick at all,the least amount possible.The thicker it is,the more apt it is to crack down the road.Make sure no pinholes in welds as noted above.You should not need any fiberglass at all.Good luck.
Have you prepared the area you welded for bondo? Didyou cleanup the area you welded and used a grinder to rough up the surface so the bondo will stick. Review these links: http://www.jeepforum.com/forum/f11/basic-bodywork-tutorial-614342/ http://www.youtube.com/watch?v=l9r2H4V3AoA http://www.youtube.com/watch?v=6T5fC0tVybs&feature=related good Luck
I'm gonna go against the grain, but...I almost always use a fiberglass impregnated filler like Mar-Glass on welded panel seams. Why? It is water proof and will keep water out of your repair. When you weld a panel, you may THINK you have it full welded with no pinholes, but in reality, that's pretty hard to do. It is a good idea to lay a thin coat of Mar-Glass over the weld seams then grind it down to flush, just in case. That way, the only Mar-Glass left is a teeny-weenie amount in any pinholes you may have. The Mar-Glass will keep any water from getting in the back side of the repair and fucking up your Bondo, or paint. Then, skim coat as you would any thing else. Good luck, -Abone.
I've worked a several Body Shops in my days. 2 of them were even the BigRig Trucking firms. We were always busy building wrecks,etc. I was involved in an argument with an Old Timer there,,the argument was wether Bondo absorbs water or not. I believed back then that it didn't. I called the 1-800 number and dammit it does allow moisture to move through it even absorb it and cause rusting under it. What Flamedabone said is exactly what I've been doing for 30 years. I get the MarGlass ~ TigerHair or Fiberglass Impregnated filler even with the strands if I can't find the other. I'll work that shit in with my fingers to force the filler into any pinholes. Then smooth it gently down and let 'er harden. Then I use 36 grit DA slow and easy and level it to where it's minimal in thickness.Then I use a good grade regular body filler. Then 80 grit that. And like was said above absolutely seal the back forcing the sealer with a brush or even fingers w gloves,etc. Remember to let it all sit a while to lose it's solvents before you pile anything on it. Those repairs will last for decades.
This is exactly what I do, there's really no way of knowing if that weld is water tight, I use a thin skim coat of duraglass over it then sand it back before I apply putty. Cheap insurance. The car I'm building now had a LOT of putty on it because the last guy must not have owned a hammer and dolly, and under all that putty, the metal was beginning to rust, that won't happen with duraglass or something similar to seal it first.
Hey, guys, I've been fighting this war for a long time now........I know you guys have heard that using a fiberglass type product will help keep rust out...but it doesn't. Think carefully about it...if there's a pinhole in your weld, water gets into the pinhole, even if the filler material is entirely waterproof....the METAL is still rusting. the filler doesn't keep it out, it either traps it it, if waterproof, or absorbs it, either way rust is starting. Better to take care with your welding, and seal up the bacsides of all welds (and bare metal) with a good sealer/rustproofer.
Weld metal panels in where there is rust? Shoot, us hillbillies just use expanding foam. Yup, you just let it expand until its done and then take out your buck knife and shave it down and presto all it needs is a skim coat of bondo. I also find that duct tape and chicken wire works gooder also. Okay, I actually have to agree with chopolds on this one.
Likes been said,,,if it's all done bone dry and then sealed on the back side moisture can't get in for a very long time. I've even put spot lights behind the work looking for those pesky dreaded pinholes. I can understand if you're lazy and trap moisture to begin with or go over old Bondini,,though.
It's easy to find pin holes by holding a light to the panel and looking at the other side for any light showing. Weld up the pin holes and your good to go, plus seal the inside, because it will be bare from welding.
Anyone ever hear of hammerwelding?? No pin holes. No fiberglass, no bondo, no lead. Only bare metal. Just like original.
All you "Bondo and no fiberglass" guys are cracking me up (pun intended). What do you think Bondo is made out of? Pixie dust and Superglue? Bondo is just fiberglass resins with a filler material (microbeads?!) in it. The only reason it is any more flexible than regular fiberglass is because there is no glass fibers holding it rigid. The gooey chemicals are the same. The adhesion is the same. And if Bondo will supposedly soak up moisture more than regular fiberglass, it is just the filler beads soaking, not the resins. Now, I was taught to apply just as Flamedabone and a few other guys above are saying. A thin coat of Mar-Glas, then Bondo on top for fine tuning. But, you gotta make sure to seal the backside with plenty of paint and/or undercoating.
I say rather than using fiberglass because you may have pinholes weld your patch up right. what are you guys doing wrong where any pinholes are not visible? there is absolutely no reason to use fiberglass in a metal repair. none. nada. zip.
try running a bead of seam sealer on the back side, then apply your plastic filler. I use the "rage ever coat gold". it's a little more expensive, but is a good product. After your done you can paint over the seam sealer on the back side and you should not have any problems.
Never have seen fiberglass to metal that didnt crack. expands differently. Try sticking with metal and try not to put Filler too thick, It'll crack too if its too thick.
That's the correct way. Duraglass, Everglass, Marglass, and Fibertech are all good for directly over the welded areas. They all use regular filler hardener so they are all polyester fillers with fiberglass strands of varying lengths as an ingredient. They make the initial coat waterproof - which is what you want. Don't confuse them with fiberglass resin and cloth. Not the same. Finish with a good grade of regular mud.
I always skim coat with mud ,Bondo Then Tiger hair and then smooth out with more bondo Never had anything crack That is only for deep fills ,Bondo is fine up to 1/4 of an inch I prefer thinner .Anything you have to fill about an inch Should be fixed
So I am a novice MIG welder and I've got some pin holes on some patch panels on my firewall. All of the grinding of the hard welds is time tedious at best. Not trying to take the easy way out here, just trying to be more efficient. Wouldn't it be better to weld the pinholes from the backside (if you have access) so you will have less weld to grind from the front? Just a thought.... somebody shoot holes in my theory.
Well lets go one step further. Once your metal work is done and every thing is hammered and dollied out. Then you sandblast the repair and apply two good coats of epoxy primer. When this is dry, scuff it with 120 grit sandpaper and apply a fibreglass based filler to the weld area. Sand this off with 80 grit sandpaper and then apply your body filler over the repair area until you get it to shape. This repair will last 3 times longer than the one with no Epoxy. Why? because the epoxy primer adhere's to the metal, has zinc in it to fight corrosion and the oxygen created when the filler hardens can not attack the bare metal and form rust. Also the epoxy resin works hand in hand with the resin in the filler. Try it, you'll be surprised how well the filler sticks to the epoxy primer. Canada, Snow Cold Salt tough on Cars. "The Old Tinbasher
I should have mentioned, I always do this as well, but I stand by my choice of duraglass over the outside of the weld area.
grew up in a collision shop, dad specialized in vette's. dynaglass or marhyde was applied over clean, ground, dry welded areas before bondo if needed. now i do more resto and rod work i metal work all areas to within a frogs hair. then etching primer followed by high build. if my frog had unusually thick hair that day and imperfections aren't blocked out by that then a skim of rage bondo always does the job. i have found i'm better at patch panels since i bought a tig. (less grinding and no pinholes) the key is getting a good sealer coat on the back side. it's been mentioned you're not doing the outside any good if it just rusts out again from inside.
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