Bondo two-part resin is well-known for being a high-quality and durable filler when it comes to car repair. Whether you have a dent or scratch on your car, Bondo filler can be used to fill in these crevices and leave behind a smooth finish.
For Bondo to work, however, it must be used with a hardener. On its own, Bondo won’t get hard. This means that it will not cure and eventually fall off after application.
Because of that reason, Bondo must be used with a hardener. When you buy Bondo, you should also buy some hardener.
In case you didn’t buy hardener or you have run out of hardener, you may be wondering – are there some substitutes to Bondo hardener?
Unfortunately, the answer is no. The hardeners made for Bondo are the only products that can help Bondo dry and cure on a surface.
There are no other known catalysts that can speed up the drying process of Bondo. And if there are some, they probably won’t react as the Bondo hardener would, and the Bondo won’t hold on for very long on the surface.
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What Bondo Hardener Options Do I Have?
Having said that, there are no Bondo hardener substitutes, but that doesn’t mean you can only use one type of hardener.
If you look deeper into Bondo hardeners, you will see that four main types are common amongst DIYourselfers.
They include; Bondo liquid hardener, cream hardener, red cream hardener, and white cream hardener.
If you ask professional detailers, they will tell you that this difference is only the hardener’s physical properties of the hardener but the chemical composition remains the same. Let’s zero in on each of these hardeners.
1. Bondo Liquid Hardener
Most of us are accustomed to Bondo hardener in a creamy state. However, there is also a liquid Bondo hardener. This particular one is made strictly for metal-reinforced filler and polyester fiberglass resin.
If you are using any of these two types of Bondo, then it should first be mixed with Bondo liquid hardener.
Even though it is in liquid form, the chemical makeup of the Bondo liquid hardener isn’t any different from others.
It still creates a chemical reaction that leads to the drying and curing of Bondo. Also, it ensures the Bondo is durable, waterproof, and holds up for longer.
The only difference you may get with the liquid Bondo hardener is that it mixes easily with Bondo. You will, therefore, have an easier time mixing the two.
2. Cream Hardener
Cream hardener is the most common type of hardener used with Bondo. It is responsible for activating the hardening process of the two-part body filler.
When you mix Bondo with two-part fillers, you get a durable and strong putty that should fill any cracks on your car metal. Even though it’s not a liquid hardener, the cream easily mixes the putty.
The cream hardener is available in a neutral color. This is ideal for those who want the color of the Bondo mixture to remain subtle.
3. All-Purpose White Cream Hardener
This is what most people refer to as a white hardener. The all-purpose cream hardener can be used by a wide range of Bondo.
It is available in the form of a cream, and it mixes easily with Bondo. It activates a chemical reaction that forces the Bondo to harden when you mix it.
This all-purpose hardener works so fast that it can enable you to sand the dried Bondo fifteen minutes after application.
White Bondo is very popular among DIY enthusiasts. This is because it is white, similar to the ordinary cream hardener. Therefore, when working on a repair project, the hardener will retain the original color of the putty.
4. Red Cream Hardener
The red cream hardener is also designed to work with all putties and glazes. There isn’t any difference between white and red Bondo other than the color.
It mixes with Bondo fairly easily and speeds up the Bondo drying process, allowing you to paint it within 45 minutes.
The red color comes in handy when you are new to using Bondo. This is because it helps you physically examine consistency.
When you use too much hardener, the color will be more concentrated and vice versa. The red hardener is therefore ideal for newbies. However, the chemical composition remains the same.
If it were the actual Bondo we were talking about, you could explore other substitutes. But, if it’s a Bondo hardener, there are only four of these options to choose from.
We can’t refer to these four as substitutes since they all feature the same chemical composition and activate the reaction which causes Bondo to harden.
The only difference between these options is the physical makeup. Most of these hardeners are in cream form, and only one is available as a liquid.
The liquid hardener is suitable for metal reinforced and fiberglass resin, which isn’t the usual two-part Bondo.
Are All Bondo Hardeners the Same?
We have concluded that there is no substitute for Bondo hardeners because they are all the same. Whether you use white or red Bondo, the chemical composition is the same.
The only difference is with the color or type of material. You can either go red or white. Or you can choose between cream and liquid Bondo hardener.
What is in Bondo Hardeners?
If you keenly read through the various types of Bondo hardeners, you will realize that they all have the same chemical composition.
3M definitely can’t disclose the ingredients they use in Bondo hardeners, but what we know is that it contains various resin mixtures that bond with Bondo and accelerate its hardening process.
In a Bondo hardener, you will find catalysts or reactants that accelerate the speed at which Bondo dries.
What Happens If You Use the Wrong Bondo Hardener?
Regarding all cream Bondo hardeners, there is nothing wrong with using them on regular Bondo. However, Bondo has special types such as fiberglass and metal-reinforced Bondo.
These require a specialized type of hardener, which in this case it’s the liquid hardener. If you use white or red hardener on fiberglass and reinforced metal, it may take longer for the Bondo to cure.
You must use the right type of hardener depending on the Bondo you are using. If you are out of options, you should use the all-purpose Bondo hardener and won’t run into any issues.
Using the wrong hardener can have drastic effects. For instance, the Bondo mixture may not cure in the required duration.
Secondly, the Bondo can fall off days after applications. You may also run into issues when sanding over the Bondo or painting over it.
Can I Use Glue as a Bondo Hardener Substitute?
Please keep off any other product that isn’t considered an official Bondo hardener. There are allegations that glue can be used as a hardener substitute.
When you consider the adhesive properties of glue, the Bondo won’t harden, and neither will it adhere to a surface that it will be applied to.
Most people assume that glue’s adhesive properties can make it mimic the characteristics of hardener, but that is far from the truth.
What about Mixing It with Paint?
Bondo can be mixed with color pigments to change its color, but that can’t replace the role of hardener in Bondo. The only way for Bondo to harden is by using a hardener and nothing else.
Before we wrap up our article, you need to take note of the following. There is no substitute for a Bondo hardener. Bondo always goes hand in hand with hardeners.
Can I Use Bondo without a Hardener?
Bondo needs a hardener and vice versa. You can’t use one without the other. If you have a project that needs Bondo filler, ensure that you buy a hardener as well.
These days, most Bondo fillers come in the form of a kit containing a hardener. It’s worth noting that even though Bondo fillers need a hardener, the latter must be used in the correct proportions.
Using too much hardener can cause the Bondo to cure faster or render it inapplicable.
Bondo needs some time before it dries to be spread easily. However, if it dries while still on the mixing table, you may have trouble spreading it on the dents or scratches.
Will Bondo Ever Dry without Hardener?
Bondo will never dry without a hardener. It will remain soft until it falls from the dent or scratch to which it has been applied.
There is a reason why Bondo manufacturers require it to be used alongside hardeners. Let’s take the automotive Bondo, for example.
After application, it is exposed to rain, sun, and many other elements. Bondo will fall off if it isn’t mixed with a hardener in the long run.
Considering how inexpensive the Bondo hardener is, there is no reason why you shouldn’t use it. It’s also widely available in nearly all body shops near you.
When buying Bondo, make sure that you also buy the right hardener. That will ensure it does its job to perfection.