Can car fillers get wet?

Asked By: Benigno Bengsch | Last Updated: 4th May, 2020
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Don't wet sand filler. Filler is too absorbant and you can have problems getting it dry plus you could cause moisture to wick through to the metal or weaken the bond between the filler and the substrate.

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Also know, are car fillers waterproof?

No car body filler is waterproof as it is polyester resin with a fine binding powder to make it into a paste, there are similar products which are waterproof but not used as car body filler.

Additionally, can Bondo get rained on? Well, the all metal fillers (under your bondo) don't absorb water to the extent that regular bodyfiller will, but believe they still do absorb some. Plastic filler absorbs it like a sponge, but keeping some heat on it should eventually evaporate the water from the plastic filler.

Besides, what happens if Bondo gets wet?

If you got some bondo wet and then dried it out, you could grind it down and it wouldn't have any moisture inside, but the metal behind it may have already been oxidized and then you'll have problems.

How long does car body filler take to dry?

Bondo mixed to the color swatch will begin to cure in less than 10 minutes at room temperature. Too much hardener in a warm environment will reduce working time, but too little in a cool environment can result in maddeningly long curing times.

38 Related Question Answers Found

Why is Bondo bad?

Bondo will not stop rust so if it is used to cover an area without the proper prep work the panel will continue to rust from the inside out. Even if you watch the big shots on TV restoring a car, they will use a skim of body filler or putty over the entire car and block it all smooth.

What is the easiest sanding body filler?

7 Best Car Body Fillers – Reviews
?PRODUCT ?FEATURES
1. 3M Bondo 261 (Best Overall) Quantity – 14 ounces Super easy to use Cures up fast Highly durable and non-shrinking
2. Evercoat 156 (Best Value) Quantity – 101 ounces Superior adhesion Excellent for heavy filling Clog-free formulation

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 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.

Does body filler absorb water?


The main ingredients in most (but not all) body fillers are talc (baby powder), fibreglass resin and styrene. The hardener contains methyl ethyl ketone peroxide (MEKP). Another point to note is that the talc in body filler is hygroscopic, meaning it readily absorbs water.

What is the best body filler for cars?

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.

Can you fiberglass over body filler?

Yes,you can fiberglass over bondo,rough the bondo up with 80 grit for a better bond,use a grooved roller to remove the air bubbles. DO NOT use Bondo on a boat, it will swell up when wet.

Will Bondo fall off?

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”. Eventually the filler will shrink and possibly crack or even fall off.

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 u wet sand Bondo?

You can wet sand plastic body filler ("Bondo" is a trade name like "Chevrolet" or "Nike") but you should carefully heat the filler with a blow torch before priming. Just take a blow torch and quickly wave it across the filler and you will see the moisture evaporating right before your eyes.

Can you wash Bondo?

I ussually try to avoid it if I can, bondo is like a sponge and absorbs water which isnt good for the bare metal underneath. The best way I have found to clean it is to blow it off with air gun and then wipe it down with prepsol to get any contaminants off before paint goes on.

Is Bondo all purpose putty waterproof?

Product Overview
Bondo All-Purpose Putty is slightly thicker than other 2-part fillers, making it ideal for repairing vertical surfaces such as doors, walls and siding. The product is formulated to be non-shrinking, water resistant, permanent and light gray in color once cured.

Will new Bondo stick to old Bondo?

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

How do you fix a bad Bondo job?


Grind all the paint and bondo off that area and see if it's a pop riveted patch, or bubbling rust, or who knows what. Then a proper fix will require removing ALL of the rust and buggers, and welding in a solid repair. Then properly hammering it to shape, and a skim coat of filler, then paint.

Can primer get rained on?

As long as the primer dried before the rain a week or 2 of the primer exposed is fine. Like stated you may have to give it a light sanding before the finish goes on.

Why is my Bondo not drying?

If the Bondo isn't dry, it's because you didn't use enough hardener or the temperature is too low. Getting it wet didn't help. Try using a heat and strip gun. It gets hot pretty quick so keep it moving.