If you have a woodwork project that needs completing but you are not sure how to fill the cracks and holes in your wood surface, then you are probably in need of a wood filler product.
There are many different brands and types of wood filler which can be applied to nail holes, deep dents, and areas of wear and tear in order to smooth the surface of your wood so that it is even and ready for painting.
Bondo wood filler is a top brand that is highly respected in the DIY sector. But how does their wood filler perform and is it the product for you? Read on for a full review covering the pros and cons of this fast drying filler.
What Exactly is Wood Filler?
If you are a novice you may be wondering what wood filler actually is. It’s sometimes called wood putty, or plastic wood, and it is a wet, putty-like substance that dries as hard as wood.
Used to prepare old, damaged wood surfaces for repurposing and finishing, and the substance has binding properties that help it to bond with the wood and stay stuck in place.
It is generally made from pulverized wood particles or wood dust that have been mixed with a binding agent for drying and a diluent for thinning.
It is a really handy product to have in your cupboard because you can make old, damaged furniture, floors, skirting or other wooden surfaces safe, smooth and ready for painting.
Now that you know what wood filler is and how it works, let’s take a look at Bondo wood filler to see how it holds up.
Bondo wood filler is marketed as a quick drying formula, and it really does perform well in this area. From the point of application, the formula takes between 5-7 minutes to dry, which is pretty swift compared to many other similar products.
The fast drying time is mainly due to the hardening agent that comes as a separate ingredient . Before applying, you have to mix the hardening agent in with the filler to create as thick or thin a consistency as you wish.
The more hardener to put in, the faster the filler will dry.
For some people, this extra step is a hassle and leaves them wondering if they have mixed it right. Sure, a pre-mixed putty is perhaps less complicated, but the process is really very simple and it allows you to have control over your own mix.
Some jobs require faster drying than others, this particularly applies to deep holes which can take a very long time to dry with other water-based putties. For these jobs, or indeed jobs where you need to move onto sanding and painting quickly, the fast drying factor is a huge plus for Bondo.
However, the fast drying speed leaves little room for error. You really need to have your method of application prepared and your technique mastered before you mix the filler with the hardener, because the moment the two substances combine, the clock starts ticking.
There is no time for digging about for your putty pallet or squeeze bag once you have mixed the two substances. But if you are prepared, then the fast drying time is a big asset.
The great thing about Bondo is that it is a waterproof wood filler. This makes it a very versatile product as it can be used to fill both interior and exterior wood surfaces.
The waterproof nature of this mix is very effective and won’t let rot or leaks seep into your wood. This means it can withstand rain, sleet and snow without losing its seal, making it a great choice for fences, outdoor skirting or even outdoor furniture and benches.
Many water-based putties are not waterproof and absorb moisture quickly, becoming soggy and soft themselves. Others advertise as being waterproof but do not stand the test of the elements.
Bondo wood filler really does what it says on the tin in this area, which we love.
Amount of Shrinkage
Due to Bondo’s fast drying time, this wood filler does not shrink very much at all.
It can be hugely frustrating to think that you have fully filled a hole in a wood surface, only to come back when it is dry and find that it has shrunk and formed cracks around the edge or dipped below the level of the surface.
With Bondo, the amount of filler that you initially apply is the amount that you end up with, making it much easier to get the finish you want, first time.
Strength of Bond
Bondo is not called Bondo for no reason. The binding agent in this mixture is very effective at glueing and fusing with the wood it is placed in.
Many water-based putties are less effective in this area, and can end up dropping out of the hole they are meant to be filling because they have failed to bond with the wood.
Bondo will not fall out or drop off after it is dry, but once again this does mean that you need to be accurate with your application (or you can find yourself chiseling away at a highly stuck mistake.
Hardness of Finish
Once dry, Bondo wood filler becomes really hard. This is a great feature if you are looking for your holes and dents to be filled with a strong and reliable substance.
Most people look for a wood filler that dries to the same hardness as the wood they are repairing, and this is so that the filler blends in with the original surface as seamlessly as possible.
However, there are many water-based putties on the market that dry soft and still have give even hours after they have dried. This is not the case with Bondo, which becomes rock solid – especially if you have put a good amount of hardener in the mix.
The hardness of this filler makes it a top choice for deep holes and crevices like nail holes or areas where damage has created an indent of more than a few millimeters.
However, it is not the best choice for slight scratches and grazes on the surface of delicate wood. For this you are far better off using a grain filler that is finer in texture and easier to sand down to a smooth level.
The strength and durability that this hard finish brings is second to none, however it does make Bondo wood filler pretty difficult to sand down. Where wood can easily be smoothed and leveled with a hand sander, Bondo generally requires a much stronger electric sander to achieve a level finish.
For this reason it is important not to over fill your holes and imperfections too much, because you do not want to give yourself a difficult and time consuming sanding job afterwards.
On the plus side, Bondo is ready for sanding within 15 minutes of being applied. This is awesome if you have lots of jobs on your list and need to be productive.
Color of Filler
One thing that many people struggle with is the color of their wood filler. It is difficult to find a putty that matches the tone of your wood, and most have to be painted in order to make them blend seamlessly.
Bondo is no exception to this rule, and it dries to a light grey / brown color. Although this tone does actually blend nicely with some shades of wood, it will not suit all wood colors.
However, it accepts paint and stain really well and is suitable for painting just 30 minutes after being applied. This means that you can fill, sand and paint your wooden surface all in a single morning, making Bondo an excellent choice for people with busy lives.
Smell of Filler
One less appealing aspect of Bondo wood filler is its smell. This stuff really does have a harsh, chemical odor that is hard to ignore when you first open the tin.
However, the smell goes away within 20 minutes of the filler drying and then there is a neutral smell. Sure, it isn’t the nicest feature of this product, but we think that it is a small price to pay for the great, strong finish that Bondo delivers.
Need for Primer
Although Bondo does not technically need to be primed before it is painted, it is never a bad idea to add a thin coat of primer first.
Sure, this wood filler is already water resistant, but a waterproof primer will help to give you that added peace of mind that no leaks or rot will set in.
What is more, applying primer will help to neutralize the color difference between filler and wood, resulting in a more consistent finish when you come to paint your surface. So it’s win-win.
Bondo wood filler really is a great choice for anyone who has wooden surfaces or old furniture that needs repairing. This stuff dries fast and hard, allowing you to get a really strong and durable finish.
It is waterproof, so can be used both on exterior and interior surfaces, has minimal shrinkage and forms a great bond with the wood.
Downsides include the pungent odor (which dissipates once dry) and the difficulty with sanding caused by the toughness of the finish.
However, if you are accurate with your application then you will be able to get your surfaces filled, sanded and painted in the space of a single hour!