Quick Answer: What To Mix Bondo On

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Proper Mixing Techniques for Body Filler (Bondo) Mix on a Spreader Mixing Board designed for the job. Do not mix on cardboard, cardboard will absorb the important resins from the body filler and hardener. Place the proper amount of Bondo filler and hardener: 50:1. Mix with a plastic or metal Filler Spreader.

What can you use to mix Bondo on?

Cut a thick piece of cardboard about 6 by 6 inches (15.24 cm by 15.24 cm). Alternatively, you can mix it on particle board or buy an inexpensive pad of disposable plastic sheets to mix the Bondo. Open the can and mix the Bondo with a stir stick if there is a layer of liquid on top.

Do I need to add hardener to Bondo?

How Much Hardener Do You Add To Your Body Filler? You need to be sure to add the right amount of hardener to your Bondo; adding more than enough will cause your body filler to dry faster and give you less time for shaping and laying your filler on your panels.

What is the best surface to mix Bondo on?

Does Bondo harden without hardener?

Without it the bondo won’t get hard. Put a small piece of bondo on a board and run a line of hardener from end to end. It will take about five minutes to mix it up and apply it.

What grit sandpaper do I use for Bondo?

First step: Prep the Surface Before applying, paint needs to be sanded to the bare metal. Make sure to sand outside of the repair area as Bondo will need to be spread and applied wider than the damaged area. (36-grit to 220-grit should do the trick for body filler application).

Should you prime before body filler?

Do not proceed to Primer Filler stage until filled area is even. Adding body filler AFTER primer filler should be avoided to prevent possible adhesion, staining and shrinkage concerns.

Can you Bondo rust holes?

While “Bondo” is the name of a 3M product, it has also become a generic term for plastic body filler, and several companies make similar stuff. The putty can be useful for filling rust holes in the most rust-prone areas of a car including quarter panels, fenders over and behind the wheels, and the bottoms of doors.

What happens if you use too much hardener in body filler?

Adding too much hardener will result in rapid gelling of the mixture, making it hard to get coverage in time. Too little hardener will increase cure time, but there’s a point where the filler won’t ever harden and you won’t know it until you try to sand.

Should Bondo be applied to bare metal?

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. A 36-grit to 180-grit surface is ideal for body filler application so that the filler has a good rough surface to grip.

How long does Bondo take to cure?

When used according to the manufacturer’s recommendations, Bondo takes 10 to 15 minutes to dry enough to form a sandable surface. After 45 minutes it’s cured enough to be painted.

Can you apply multiple coats of Bondo?

Unsanded filler tends to have a film on it and the next coat won’t bond as well unless the lower coat is abraded. You don’t need to level it but you should scuff it with some 80/120 before applying the next coat.

How long should Bondo cure before sanding?

Allow the putty to dry 15 minutes at 77 degrees F (25 degrees C). In cooler climates, putty may take 20-30 minutes to dry. 7. Using 3M™ Sandpaper 80 grit, sand and shape the filled area to the contour of the surface.

Will filler go off without hardener?

Wood fillers can be used to reinforce softwoods or rotten woods structurally. However, this is usually only a stopgap without using a hardener as well. You can use both in conjunction to save ancient, fragile woods.

How long can Bondo be left unpainted?

Between life and work, the longest time period the bondo would go Unpainted would be about 2-3 weeks.

Can you put body filler on Baremetal?

Before adding any filler, you should get the metal fairly close. For small repairs, you can bog directly over the bare metal. If the repair is larger, or you’re looking for a longer-lasting job, apply a base coat of epoxy primer before laying on the filler.

Can you put body filler over rust?

The mere application of body filler over a substrate won’t stop rust, Miller said. Fillers might contain corrosion resistance and slow the process, “but they’re not gonna stop it,” he said. Put filler on rust, and “(the rust) may continue to grow,” he said.

Can I paint straight onto filler?

When using filler it is always good practice to thin down the first coat of emulsion when painting the surface. We would recommend you rub down the surface and apply another coat but thin down the paint with 20% water – this will seal the surface and give a more uniform finish.