I use Malco half time on cut bare steel for my roughing in (like a hood with a shallow broad dent). I don' t like to use it for my finish feather because I feel it's too thick. I found the Dynatron great for that. They have it at O'Reiilys, and it spreads real nice with hardly any chance of air bubbles. It does need to be mixed with hardner like the rest.
After, you worked an out and it's ready for filler don't forget to ruff up the area a little so the filler has something to hold on too. CRUISER
That is what I use too, yea I think the Rage Gold is a little better, but the Z-grip is half the price....
Ive only been doing bodywork for a year now so im no expert...but here are a few things ive picked up so far. When I do the final bodywork on my truck I will be applying filler over the epoxy primer. In most collision shops I have seen the filler is applied directly over properly prepped bare metal. So I guess it depends on how long you plan to keep the car. Epoxy primer is supposedly bulletproof so if you ever get a rock chip the filler will not absorb moisture and rust out the base metal. So far as I know epoxy primer is the only type of paint that filler can be applied over...the way i understand it the epoxy should be allowed to fully cure, then sanded with 80 grit on a da to give the filler something to bite into. Like someone already mentioned, start by roughing out the dents before filling them. In my opinion the key to getting good results with bodyfiller is how well you rough out the metal. If you have access to the backside of the panel you can bump up the low spots and tap down the high spots, then use a course bodyfile to reveal the remaining high and low spots. Roughing out the metal until its nearly perfect is a lot more rewarding and less frustrating than simply slapping mud on it and sanding. If you do the roughout good your work should only need 2-3 skim coats of filler before its ready for primer surfacer.. I absolutely hate working with bodyfiller, so i will spend more time doing roughout than filler work. I did this 32 ford grill a couple weeks ago, its hard to tell from the pictures but it had several small dents and low spots, as well as some poorly done pick and file work. I ended up removing 98% of the damage by simply bumping up any low spots, tapping down high spots, and filing over it with a bodyfile to smooth out the remaining flaws. After 3 hours on the one side i ground the metal with 40 then 80 grit, then sanded it with a DA. So for 6 hours of work on the whole shell it is now ready for 3-4 coats of primer surfacer, no bodyfiller required. Like i said Ive only got about a years worth of experience so you can take my opinions with a grain of salt
i bought a can of por-15 filler, it works great but costs quite a bit. i would use it more, but it just cost to much, so i use evercoat products.
i used some filler a while back in the local body shop,it was so hard 40 grit wouldnt touch it,but 80 or 100 would take it down quick.and hardened so quick,even with a small amount of hardener,i could only mix small globs.it finished really nice,zero pinholes,but body guy says it has a lot to do with mixing. i will be using etch primer on all my bare metals,from now on,always on bare metal before. i think it was a dynatron product he was using in the shop.
Glenn is right. There needs to be corrosion protection on the bare metal. The best corrosion protection consists of all the layers of the repair together. The forgotten first and best step is what the factory uses on bare steel. That is a phosphate coating. When we grind off the paint and primer to make the repair and prepare for filling, we usually remove the OEM phosphate coating on the area to be repaired. Without that phosphate the steel starts to oxidize instantly. In the real world of collision repair that is performed by technicians working on commission, any step that goes further than grinding to clean bare steel, just takes money out of the paycheck. This repair process is good and it probably will hold up from 6 to 20 years, depending on care and climate conditions, by which time a street driven daily is shot or traded off. Body filler is a layer of corrosion protection. Primers are a layer of corrosion protection. They both can contain or trap moisture, which can cause the rusting under the repair. There are so many different primers available with different properties. The best corrosion resistant primers for automotive repair are long gone since we regulated heavy metals out of these products. In production shops, using metal conditioner to rephosphate the repair area, or using a primer under the filler to seal or protect the steel, is just too time consuming for a good profit. In specialty shops, rusty metal is cleaned, sandblasted, and I hope rephosphated before primer, as that is the best available system. If you prefer filler over primer, make sure that the primer will not shift or swell from soaking solvents. Todays filler technology will stick to good cured, sanded, clean primer--it's HELL trying to get it off your fingertips! When I'm working on old cars, I like to rephosphate the steel in some form and I still like filler over bare metal. I try to be on top of my work area temperature and humidity to minimize the chance of moisture on the steel, and this goes for priming under filler also. When choosing your undercoats/primers seek out guys like Glenn that deal with a wide variety of fillers, primers and coating systems. Usually tech reps have access to some factory help and some crossover products like aricraft and fleet primers and finishes that go a step or two further in corrosion protection and longevity of the coating system that may be of interest for a specialty car or project. One of my biggest pet peeves is the term "epoxy". There are so many different epoxy primers and coatings with different characteristics for prep, handling, spraying, coverage, film build, solids content, cure time, recoat window, etc. EPOXY is not spelled M A G I C! They are not all created equal. There are some real good epoxy primers, and a lot more mediocre to poor ones that do not have very good corrosion protection. The same goes for other types like etch primers, urethanes, and polyester primers. If you read some tech sheets and compare information you may find a better system. If you don't want to read the tech sheets, then pay attention and ask for help from guys like Glenn. One thing you probably will find in the tech sheets for most primers, except self-etching primers, it that removing rust by sanding sand blasting or metal conditioner (phosphating) is usually reccommended before priming. overspray
Chemists have taken over the autobody/marine filler technology. There's not only one type of "bondo" like Kragen supplies. If you look at the EVERCOAT website, there are over a dozen types of body fillers by them. http://www.evercoat.com/products.aspx Some (like Z-grip) specialize in bare metal adhesion, and others (like RAGE) cover both painted and bare metal spots. I'm sure it's the same basic formula with some little tweaks in the recipe, probably more to save their asses in case of failure/chipping, but there's obviously no absolutely correct answer for either method. TP
I think the major difference in the primer over filler or vice-versa is a collision industry vs. restoration thing. The body shops have about 2-3 days to turn something out the door, and don't have the time to spare waiting for primer to cure for a filler application. The restoration guys are more likely to do a metal finished repair, with less filler, and will want the overall in epoxy first. Then there's the guys doing their own stuff at home, where it may get dragged out over weeks, months, or even years. For them, an overall of epoxy first makes sense to protect the metal from flash rust, especially if doing a shakedown before final finish. The argument will never go away, use what works for you. But Tedley, I think if you would look at it from one of the other perspectives and not the Collision shop environment you've been in for so long, perhaps it isn't so stupid after all.
having spent ten years as a body man , never using primer under filler i would really like an answer to this question. primers change heck fillers have changed and alot I want the filler to stick and the repair to last ...what is a best practice by the way waterborne should not be feared...chevy used this in 1980 on camaros it is great stuff today as well
Ring the bell, Bob, we have a winner! Bondo brand products belong in only on place: the dumpster. Seriously, if you use this stuff, try one of the other fillers mentioned on this thread. You have no idea how bad you have it.
First off, todays waterborne paints are ten times better technology than what was used ten years ago. I love water, and would never want to spray solvent base coat again. But thats just me, I like technology. The prime first then filler debate will rage on for years to come. Ask five guys how they prep things for paint and you will get five different answers. Some better than others. Call me and we will talk.
Although I can see how one would want to epoxy the whole car right away sometimes, you should still remove the primer when you go to apply filler. One thing that hasn't changed - in my expereinced opinion - is that filler shouldn't have primer under it. Filler was disigned to adhere to bare metal and that's what is says on the MSDS sheets. I've been doing it like that for 35 years and have NEVER had a problem, Of course problems CAN arise - but it's mostly from not cleaning, grinding and wiping with solvent IMMEDIATELY prior to application. From the Evercoat Website - Z-Grip: Z-Grip® An advanced, clog-free, lightweight body filler for today’s high tech metals. Formulated with ZNX-7® for superior adhesion to galvanized steel, bare steel and aluminum. Part of the MetalWorks® System that honors the OEM corrosion warranty. Contains Hattonite™ for effortless sanding. Blue cream hardener included. "OEM CORROSION WARRANTY" when applied over BARE steel....... /end discussion.
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