The short answer is filler companies suggest it needs to go on bare metal, and epoxy companies suggest you put filler over epoxy so they can sell more of their product..
In this manner, can I use body filler on bare metal?
Evercoat fillers are designed to work over bare, properly prepared substrates such as: steel, aluminum, galvanized metal, fiberglass, and SMC. Fillers and putties will normally work OK over properly sanded (80-180 grit) cured OEM paint.
Subsequently, question is, can you put body filler on paint? Fillers and putties will normally work OK over properly sanded (80-180 grit) cured OEM paint. However, with so many different types of aftermarket paint available (lacquer, enamel, urethane, water-based). We recommend that all paint be removed where filler is to be applied.”
Thereof, can you put body filler on primer?
Yes. You CAN apply over sanded 2k primer, or bare metal. Be sure to have the area sanded with at least a 150 so the filler has some TOOTH to grab to.
How big of a dent can you fill with Bondo?
Its OK to use bondo up to 1/4 inch. If it is your pride and joy, I'd do a little more work to reduce the dent. Using Metal-2-metal will make it a little stronger than normal bondo.
Related Question Answers
Do you have to prime over Bondo?
You should use a "direct to metal" (DTM) primer to help top coats stick to the metal but it's not needed under body filler most of the time. Once the metal is primed then you can apply a "filler primer" (2K) to help hide scratches and minor surface irregularities.Is Bondo waterproof?
Bondo Fiberglass Resin is designed for repairing cars, boats, snowmobiles, jet skis, bathtubs and showers. Bondo Fiberglass Resin is waterproof and is compatible with all paints, including gel coat and marine paints.Can I Bondo over paint?
Bondo Ultimate can be applied directly over sanded and cured primer and paint. This filler remains easy to sand for days after the application.How do you apply Bondo smoothly?
For a super-smooth finish, apply a very thin layer of glazing and spot putty with your palette knife. Let it thoroughly dry, then paint. Sand with at least 220-grit paper between coats. For more on Bondo, go to bondo.What is the best primer to use on bare metal?
Two-part epoxy primers go one step further by including zinc phosphate, which increases its corrosion-inhibiting properties. Simply put, epoxy is the best primer for bare metal, making it excellent for newly fabricated metal parts or ones that have been fully stripped.What is the best auto body filler to use?
The Best Car Body Filler - 3M Bondo 261 Lightweight Filler. See More Reviews.
- Permatex 25909 Liquid Metal Filler. See More Reviews.
- 3M Bondo Professional Gold Filler. See More Reviews.
- Evercoat 156 Light Weight Body Filler.
- 3M Dynatron 492 DynaLite Lightweight Body Filler.
- Evercoat 112 Rage Gold Premium Car Body Filler.
Will high build primer fill pinholes?
Any high-quality automotive primer will cover and hide the scratches. Pinholes are not so easy to fix. Unfortunately, primer is very thick and does a horrible job of filling pinholes. You've no doubt heard the horror stories of builders spraying coat after coat of primer trying to get rid of them.Can you put body filler over polyester primer?
After applying the poly prime, block it. If you need more fill for low spots,just use polyester filler or polyester glaze. Polyester prime is basically thin body filler so theres nothing wrong with putting the filler over the prime. Just make sure its sanded with 80-100 grit where you put you filler.What is filler primer used for?
About Filler Primer Spray Rust-Oleum® Filler Primer is a hi-build formula that fills in minor imperfections in the surface and improves top coat adhesion and appearance. For use on metal, wood and fiberglass surfaces.Should you prime before body filler?
We use 36 grit grinding disks to clean and texture the metal before applying filler. You can even use something as fine as 80 grit, just be sure to push the filler into the scratches so that it bonds well. No priming or etching is needed as long as the metal is textured and not rusted.What is a 2k primer?
2K is usually thought of as a "filler primer" that is sanded to help level the surface and take out slight imperfections. Epoxy primer is a "direct to metal" primer that can be a little gummy and not as good for block sanding.Can you put putty over primer?
You can use glaze putty over primer. Either pin holes or lows or something that pops up after it's been primed on occasion. Let me give you one hint to help you, and you may be doing this, but use a Guide Coat in your body filler stages.How soon can you sand Bondo?
I've used bondo quite a bit. Generally, in a matter if a few minutes it will start to harden and get rubbery. At that point, you can carve it up with a utility knife, a hand planer or a bondo rasp. Just make sure you leave enough to do a final sanding, usually within 10 to 15 minutes you can start sanding it.Can you put Bondo on top of Bondo?
Yes, you can layer bondo over bondo as much as necessary with no problem.Can you apply body filler over rust converter?
Using a rust converter ,acid under the epoxy primer that I'm using is a no go. The primer I'm using is Southern Polyurethanes. And they suggest apply the body filler over the primer.How thick can you go with body filler?
Thickness. There is no minimum thickness for Bondo, but there is absolutely a maximum. You do not want to apply body filler to anything that is thicker than about a 1/4”.How do you get Bondo off paint?
If its on Paint, I would suggest using a plastic type paint scrapper (or anything made of strong plastic so you won't scrape the paint), put it on the base of the bondo spot, but not touching the paint, and giving it a good wack. If there's wax on the paint, it will pop off.What is lightweight body filler?
Product Description 3M™ Light weight body filler is a two component material that is vacuum processed to create a smooth texture. 3M™ Lightweight body filler cures tack free in 20 minutes with good sanding and handling characteristics.Will Bondo stick to painted surface?
Do not slap Bondo onto a smooth painted surface, it is not going to stick very well. The paint should be sanded off, to the bare metal, and then apply the filler. 
