how to use Bondo as a wood filler?

Bondo is the go-to product for filling holes and cracks in wood. It’s easy to use, affordable, and can even be used on unfinished wood. But there are some things you should know if you want to use it effectively.

What do you mix in Bondo for wood filler?

Bondo is a polyester resin, which means that it must be mixed with a hardener. The hardener is a catalyst that speeds up the curing process and makes Bondo easier to sand.

The ratio of hardener to Bondo depends on how you plan on using your wood filler—if you’re planning on painting over your bondo, you can use more hardener so it will cure faster than if you were going to leave it unpainted.

The amount of hardener needed also depends on the temperature: at low temperatures (50-60 degrees Fahrenheit), 1 part by volume of hardener to 6 parts by volume of Bondo should be used; at medium temperatures (70-80 degrees Fahrenheit), 1 part by volume of hardener to 8 parts by volume of Bondo should be used; and at high temperatures (>90 degrees Fahrenheit), 1 part by volume of hardener to 10 parts by volume of Bondo should be used.

Can I use Bondo to repair rotted wood?

Bondo is not recommended for repairing rotted wood. Bondo is a polyester resin that’s designed to fill holes and cracks in surfaces, such as wood.

However, if the wood is rotted out, you’ll need something stronger to repair it.

If you have a rotted piece of furniture or some other piece of wood that has gotten wet and/or damaged by insects or other pests, it may be better to look into polyurethane products instead of Bondo since they’re typically stronger than polyesters (in general).

Do you have to Prime Bondo on wood?

This question comes up often, and the answer is no. You don’t have to prime Bondo if you want to use it as a wood filler.

However, in order for it to work properly as a filler, you need to prime the area that will be filled with Bondo first.

This can be done by brushing on a coat of paint or stain, then sanding it down once dry. You could also use a primer specifically designed for bonding surfaces together before applying Bondo (we recommend Zinsser Bullseye).

Does Bondo need to be primed?

Bondo is a two-part epoxy putty that can be used as a wood filler. It is not a primer, paint, or sealer and does not need to be primed.

The main reason Bondo does not need to be primed is that it’s designed for use in repairing dry, cracked or damaged surfaces on your boat or car (or wherever else you would want to use it).

What’s better wood filler or Bondo?

Bondo is a go-to filler for homeowners who want to fix a variety of wood problems. It’s great for filling holes, cracks, and dings in wood surfaces. It’s also ideal for filling gaps between metal and wood surfaces.

However, Bondo isn’t as durable as other fillers like epoxy putty or polyurethane filler.

How thick can you apply wood filler?

Applying the Bondo to the wood until the surface is smooth and level is the most important part of this process. If you apply too much Bondo, it will be difficult to sand down.

Also, too much Bondo in deep cracks can cause air bubbles that make it hard to sand down properly.

Do you need to sand Bondo?

The short answer? Yes, you do need to sand Bondo. When applying Bondo as a wood filler, you’ll want to make sure that the surface is smooth and even so that it can be painted over easily. If not, the paint will crack or peel off when dry.

As long as you follow our steps below and use a light hand while applying the Bondo, it should be easy enough to sand down using regular sandpaper (150 grit or higher).

You could also use an orbital sander if you’re working on larger pieces of furniture or other projects where saving time is important!

Before we get into how much is too much when it comes to using Bondo for your project needs, let’s talk about what kind of wood filler works best with different types of materials.​

How do you smooth out Bondo?

Once you’ve applied Bondo, you’ll need to sand it smoothly. You can use a sanding block for this, or if you want to get fancy, you can use a sander.

If you don’t have access to sanding blocks or power tools, don’t worry! Hand sanding is perfectly fine as well. Just make sure that when working with Bondo (or any other filler), it’s important not to apply too much pressure because this could cause the filler to crack and fall off.


If you’re looking for a way to repair some damaged wood in your home, then Bondo might be the perfect solution.

It’s easy to use, affordable, and can cover up small cracks or holes in your furniture without a lot of paint.

You just need to make sure that you have all of your ingredients before getting started on this project so you don’t miss anything important!

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Martin Flood

Martin Flood has been working in the construction industry for over 20 years as a general contractor with expertise in remodeling projects that are large or small. He has furthered his career by specializing in epoxy resin flooring, providing excellent service to both commercial and residential clients. Martin’s experience enables him to offer professional advice on how to choose the right type of project based on your needs and budget.

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