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.

Then, How long can Bondo be left unpainted?

about 2-3 weeks

Considering this, How long should Bondo cure before sanding? 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.


24 Related Questions and Answers Found 💬

 

What is the difference between epoxy primer and etch primer?

Epoxy primer is catalyzed and self etching is solvent based. Self etching primer bonds well to bare metal surfaces and can be top coated in a short period of time. Epoxy primer can be applied in heavy coats which can be guide coated and block sanded to remove small imperfections in the body.

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.

Do I need etch primer on bare metal?

1. Over Bare, Clean Metal – Epoxy primers are amazing at sealing up bare metal and from allowing moisture or corrosion to creep in. Etch primer included, epoxy primer is about the only bare metal primer you could leave a vehicle outside in without rust forming back under the primer quickly!

Can you spray epoxy primer over old paint?

You can coat epoxy or urethane primers over old paint. I personally would not, but you can. It won’t craze the paint like spraying laquer on old enamel. But you would really be better off just sanding it down to the factory primer, at least.

How do you prep bare metal for painting?

To properly prepare new metal surfaces, use mineral spirits to remove grease and apply a rust-inhibitive primer before painting. For painted surfaces that are in sound condition, remove dust with a clean, dry cloth, de-gloss the surface with light sanding, and wipe with mineral spirits to ensure good adhesion.

Does self etching primer stop rust?

After you remove the rust scales from the metal on your car, you need to apply self etching primer. It’s a mix of phosphoric acid and zinc. It’s purely a surface coating, and it doesn’t stop the rust. It does, however, prevent the rust problem from worsening.

How long does Bondo take to dry without hardener?

In theory, properly mixed Bondo can be applied in any thickness, but beware of gravity-induced sagging. Curing time depends primarily on ambient temperature and how much hardener you add. Bondo mixed to the color swatch will begin to cure in less than 10 minutes at room temperature.

What does filler primer do?

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 you put 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.

Can I put Bondo over rust converter?

Rust converter converts the rust to primer. You can prime and paint over it. Clean the loose rust off first before converting of course tho. I re-read yes you can bondo over it.

How long before I can 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.

What is the best auto body filler to use?

The Best Car Body Filler
  1. 3M Bondo 261 Lightweight Filler. See More Reviews.
  2. Permatex 25909 Liquid Metal Filler. See More Reviews.
  3. 3M Bondo Professional Gold Filler. See More Reviews.
  4. Evercoat 156 Light Weight Body Filler.
  5. 3M Dynatron 492 DynaLite Lightweight Body Filler.
  6. Evercoat 112 Rage Gold Premium Car Body Filler.

How do you prepare metal for Bondo?

What does self etching primer do?

About SelfEtching Primer

Rust-Oleum® Self Etching Primer prepares bare metal, aluminum and fiberglass surfaces to promote maximum adhesion and smoothness of the top coat. This product is formulated to stop rust and is an essential step to achieve a professionally finished look.

Can you paint over Bondo?

Clean and sand or scuff the surface to prepare it for body filler — it will not adhere to smooth, dirty or oily surfaces. Generally, if paint will stick, so will Bondo. Fully cured Bondo is harder than soft pine, and is not flexible.

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.

Can you Bondo over old Bondo?

Yes, you can layer bondo over bondo as much as necessary with no problem.

Can body filler go over primer?

Can you apply body filler or bondo over primer filler? 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.

What does filler primer do?

Filler primers

In most cases, the filler primer or high-build primer is also a urethane product. Because it has the texture to fill pits and imperfections in the sheet metal, an unsanded primer coat would be too rough to paint over without further preparation, which includes a sealing primer.

What is the best auto body filler to use?

Epoxy primer can be used on most anything from bare metal to over top of body filler and old paint. If you just finished a repair panel, welding, or even stripping a panel you can seal the metal up with Epoxy Primer immediately to keep it from flash rusting and causing additional rust.

Can I put Bondo over rust converter?

Rust converter converts the rust to primer. You can prime and paint over it. Clean the loose rust off first before converting of course tho. I re-read yes you can bondo over it.

Can you apply body filler over sanded 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.”

Can you apply body filler over sanded paint?

Filler primer is a thicker primer that fills in scratches and uneven surfaces before painting. It’s perfect for places like the cut edges of MDF and plywood. Once filled and sanded it will be just as smooth as the rest of the surface.

How many coats of primer do you need on bare metal?

Spray in short smooth strokes from side to side across the metal, holding the can about 10 inches from the surface. Two coats of primer should be plenty. Let the primer dry thoroughly based on the manufacturers suggestion before painting. Paint is applied in a similar manner, and up to 3 coats can be used.

Do you have to prime bare metal?

Some coats of a good primer will make it even stronger. Any time you sand away from your vehicle’s paint and expose bare metal, you should apply primer before you paint, sanding lightly between coats to be sure youve got a smooth surface every time.

Can you putty over paint?

No, you have remove the paint by using paint remover or just scrap it down, and you can directly apply Wall putty or you can use wall primer and then wall putty. If you apply on paint, it wont last for long, it will peel off in 1 or 2 years.

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.

How do you seal bare metal?

Some coats of a good primer will make it even stronger. Any time you sand away from your vehicle’s paint and expose bare metal, you should apply primer before you paint, sanding lightly between coats to be sure youve got a smooth surface every time.

Should I 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.

Can you put body filler over polyester primer?

Epoxy primer can be used on most anything from bare metal to over top of body filler and old paint. If you just finished a repair panel, welding, or even stripping a panel you can seal the metal up with Epoxy Primer immediately to keep it from flash rusting and causing additional rust.