Best Wood Hardeners

rotting-deckA rotting piece of wood is a sad sight indeed. We rely on this material for so many things, and yet, it is a relatively short-lived substance. Thankfully, there are many creative ways in which you can restore old or rotted wood to its former usefulness.

Perhaps the easiest way is to use a wood hardener. This is a glue-like product that soaks deeply into the wood, fortifying it against further rot while also protecting it from moisture. Let’s look at the best wood hardeners that I could find.

Best Wood Hardeners in October, 2021

1. Minwax High-Performance Wood Hardener – The Classic

Minwax is one of the more trusted brands when it comes to these kinds of products. Looking at the reviews for this product, we can see why that is so. This is a product that falls right in the middle of our price ranges, meaning that it is not particularly cheap or expensive. It’s right in the middle, which is fine for most people.

This company also makes an excellent wood filler, and the wood hardener is meant to work in unison with that product. Thus, you already know what kind of filler to buy when you work with this stuff. I also like the way that this hardener darkens the wood, improving the appearance and bringing out the grain in a manner similar to staining.

Great Penetration

A lot of this hardener’s properties come from its thin and watery consistency. This feature provides both benefits and problems. On the plus side, this stuff absorbs into the wood very quickly and very deeply. If you really want something that will go all the way to the core, this is the right bottle for you. However, that thin consistency also makes it a little harder to use, especially on vertical surfaces.

Not Very Forgiving

I do have some problems to report. This substance dries very quickly in spite of its thin consistency. This might be a good thing when you’re doing a rush job, but you shouldn’t be doing something like this as a rush job anyway. The fast drying time gives you less time to correct any mistakes, so it’s a slight problem.

A bigger problem is the fact that this stuff contains some rather harsh chemicals. As such, you need to be careful not to get any of it on your hands. Never use latex gloves when applying this hardener, as they will melt. Go with some rubber gloves to avoid this little hazard.

  • Trusted brand
  • Meant to work well with wood filler
  • Absorbs and dries very quickly
  • Works well in a sprayer
  • Also functions as a stain
  • Watery consistency runs easily
  • Not much working time
  • Dissolves latex gloves

2. PC-Petrifier Water-Based Wood Hardener – Great For Small Jobs

Here we see one of the cheapest products on our list. However, I didn’t list that as a “pro” because low prices can sometimes equal shoddy manufacturing. Still, the reviews for this product indicate that most people are happy with its performance.

Less Drip, Less Penetration

This stuff is a little thicker than the Minwax hardener, which makes it slightly less absorbent. On the upside, it is a lot easier to brush this stuff onto a rough surface. A thicker consistency is also nice when you are working on any vertical surface. PC-Petrifier doesn’t drip quite as much as the competition, leading to less aggravation for the user.

Gentle And Versatile

This stuff is also environmentally friendly. You certainly don’t want to drink it, but it doesn’t have nearly as much stink as some others. Also, it is non-toxic once dried. This product can even do double-duty as an outdoor primer, as it is perfectly suitable for painting. By using this stuff, you won’t have to remove the old paint.

The Downsides

As for problems, I do see a few. That nozzle tends to squirt big globs that are harder to smooth out. Also, the manufacturer says that this product is not to be used for structural repairs (meaning wooden beams that bear weight). This is a clue, and it tells us that this product does not penetrate as far as some others. Finally, there is a problem with filler compatibility. This stuff cannot be used in combination with any wood filler that contains borate, and many of them do.

  • Slightly thicker consistency
  • Pretty cheap
  • Easy cleanup
  • Environmentally friendly
  • Doubles as an outdoor primer
  • Not recommended for “structural repairs”
  • Nozzle tends to squirt too much
  • Doesn’t work with some fillers

3. Bondo Rotted Wood Restorer – Not Just For Cars

Most people think of Bondo when it’s time to fix a rusty car, but they also make an excellent wood hardener. This is what some people might call a premium option, as it offers a high level of quality and convenience. Of course, the extra quality and convenience don’t come cheap.

Expensive And Hazardous

This one is about twice as expensive as other products on the list (on average), making it a poor choice for those on a tight budget. It’s also not the best choice for those with breathing problems or smokers. Why do I say that? Because this stuff gives off some volatile and harmful fumes and is also highly flammable. You’d better make sure to put out that cigarette before you open this can.

Very Speedy

Still, there are many good things about this product. First of all, it’s one of the most fast-drying wood hardeners that I have seen. It only takes about two hours to dry fully, even though it’s a good idea to let it cure for an additional 24 hours. The downside of this is a very narrow working time.

This product is meant to be mixed with wood filler, making a putty-like substance that can be applied like clay to any wooden surface. This is pretty cool, but you had better be able to mix and apply this stuff quickly because you only have three to five minutes before it starts to set. After two hours, don’t even bother trying to correct your mistakes.

Very Strong

When it comes to strength, this one gets some serious points. It is meant to penetrate deeply and reinforce the wood. Obviously, that only happens when you use the product without mixing, which you certainly can do. Even though the quick dry time can be a bear, it does mean less waiting between coats.

  • Can be recoated after only two minutes
  • Dries in only two hours
  • Extremely water-resistant
  • Very deep penetration
  • Trusted brand
  • Pretty expensive
  • Slightly dangerous
  • Not a lot of working time

4. LiquidWood Kit – The Old-Fashioned Way

This is another product that might be described as premium, but it’s not quite as expensive as the other one. However, it comes with one big inconvenience. Liquidwood is basically just an absorbent epoxy. Like most epoxies, it has to be mixed with two different substances. This raises the price even higher, since two cans must be purchased. Thankfully, this product is sold in a kit, saving you a little money.

Extreme Strength

The best thing about this product is the strength that it produces. This hardener is rated for structural repairs, so it should restore any piece of wood to its original strength (and possibly make it stronger than ever). This makes it a great choice for those who are looking to preserve something made of softwood. Softwoods like pine do not tend to last as long, but Liquidwood will make them harder than Oak.

Not only does this stuff provide a strong repair, but it also provides a waterproof and weatherproof finish that is suitable for outdoor projects. It isn’t very visible once it dries, so it shouldn’t affect the appearance of your deck or its furniture.

Kind Of Slow

This product takes a little bit longer to dry than most others. If you are an accident-prone person, this will be a good thing. You should have at least thirty minutes to correct any mistakes that you have made, and the whole thing won’t harden up for about 24 hours. In some cases, it may take even longer. Temperature and humidity will play a role in the dry time, so it’s hard to know for sure.

Although this long dry time is very forgiving of mistakes, it does present a problem when you are working on a vertical surface. There is a lot more time for this product to drip and run down a wall, for instance.

  • Strong enough for structural repairs
  • Can be used indoors or outdoors
  • Bonds well to most wood fillers
  • Almost invisible once dry
  • Long working time
  • 2-part epoxy mixture
  • Kind of expensive
  • Not as good for vertical surfaces

5. J-B Weld Original Version Liquid Hardener – The Moisture Murderer

This product comes from a company that is best known for their two-part metal epoxies. Their wood hardener is less well-known, but works just as effectively. Unlike J-B’s other products, this one requires no mixing or special preparation. You just dip the brush in the can and slop it on there. It has a watery, milky appearance and soaks easily into rotted wood.

Draws Out Moisture

This product is formulated in such a way that it actually draws moisture out of the wood as it dries. This is great because you will have less chance of internal rotting. Sometimes, a hardener will not penetrate deeply enough, causing it to form a hardened outer layer that traps moisture in the middle. As you might guess, this trapped moisture will rot the wood from the inside. It’s good to see that at least one company has given us a way to prevent this issue.

Long-Lasting Repairs

Most reviews seem to agree that this product will last for years once applied. Some people claim that it can last as long as ten years before needing to be re-applied. Also, the quick-drying nature of this product makes it great for non-horizontal projects. If you are trying to seal up the wall of an old log cabin (for instance), a quick-drying formula can be a real plus.

Don’t Breathe This Stuff!

You do need to be a little bit careful with this one, as it is quite toxic. Keep it away from your kids and your pets, and you should be fine. Also, wear a face mask when you start brushing this stuff onto the wood so that you don’t inhale deeply and get sick. Thankfully, this bad smell will go away when the hardener has dried.

Some reviewers insist that the product has changed its formula in recent years. They say that the old formula was acetone-based and provided stronger results. However, this may very well be untrue.

  • Easy to use
  • No mixing
  • Meant to draw out moisture
  • Long-lived
  • Quick-drying
  • Requires sanding between coats
  • Fairly toxic
  • Product has changed formulation


Even though all of these products do the same thing, they do not perform the same. The small variations are very important here, so make sure you understand the importance of choosing carefully and wisely. After all, you will only get one shot at this project! Once a wood hardener has been added to a piece of wood and dries, you are stuck with the results. This is a non-reversible process, and that’s exactly why we chose to create this article. With a little bit of knowledge under your belt, I hope that you will now be able to choose well and attain the best of results.

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Christine Raissis
Christine Raissis
5 months ago

Hello. I live in Toronto and I have a beautiful garden arbour and the upper and lower part of the posts are rotting – the structure is even starting to be a little wobbly when you push it.. I would really like to keep the structure for a few more years if possible as it will be very expensive to rebuild. I have never done anything like this so would like some advice.

  1. When I started to dig out the rotting parts it is still quite damp. Should I be using a hairdryer or something to dry it out or can I use the wood hardener directly on it? Maybe a few douses? Given that it is a large piece, any recommendations of preferred product? I tried a small bottle of Varathane wood hardener so far but I think that may not be the best choice.
  2. There are some large gaps at the base/corners which I need to fill. I was thinking of using a wood filler + hardener or an epoxy or even filling the space with an expanding foam filler and then topping it up with wood filler or some sandwich combo. Some sites have suggested I put screws in to bolster the stability. What would you recommend to provide strength and be cost effective.

Thank you very much… hoping what you recommend is available in Canada!

Joe Smith
Joe Smith
5 months ago

I have some 6×6 cedar posts that have rotted, while standing on the concrete slab under my porch roof. I cut about 6 inches off the bottom to find solid wood. However the wood has a lot of cracks in it. Will the minwax hardener bind these cracks? The end cut had fine wood powder at the base and spintered soft wood. When the cut piece hit the ground it fell apart in 3 pieces. I could pull the wood apart with my hands. Hopefully the hardener will save the remaining hard but cracked wood. Thanks

jeniel stephens
jeniel stephens
6 months ago

i am building a dollhouse from a kit and the wood supplied is terrible. it is splintery, peels and breaks away way too easily when sanded. and it is too rough to not sand smooth, especially the cut edges of the pieces. what can i do, if anything, to make the wood more durable and not so rough & splintery?

laura bohle
laura bohle
7 months ago

I have a 60+ year old wood fence with the slats weaving horizontally between the posts. The slats are rotting at the ends where the nails were put in. Some have even split. Short of replacing the slats, which product that you mentioned in this article would be the best to be able to brush or spray on the ends of the slats so I can put new screws in?

Don Jensen
Don Jensen
1 year ago

Great information and a great site.
I have a motorhome with the subfloor in the kitchen area damaged by a long term leak. It is a sheet of plywood (probably one-half inch) with the top layer delaminated and raised up about one-half inch. The plywood is virtually impossible to replace as most of it is under the slide-out. I am thinking of making several thin parallel saw cuts, then apply a wood hardener. I would then place some heavy weights on the plywood, separated by wax paper from the plywood. Is this feasible and what hardener would you recommend?

Lisa Catlett
Lisa Catlett
1 year ago

I’m a girl in Mississippi who is restoring 85 year old windows in which have been caulked and painted completely shut all the way around there’s 18 of them . A lot of the window sills actually disintegrated only using a painter’s tool to scrape paint and years of mold and mildew from them . The outside very bottom plate in encased in siding and the inner plate , the one in the middle, is really soft and spongy and rotten . I do not have the budget for my labor to take it all down to a point of good solid meat so repairing and stopping any further fallout is my main objective. My boyfriend , who has been a carpenter for his whole life, has not really taken the time to teach me anything at all so I have come up with some pretty awesome procedures on my own. He forbade me to use my fiberglass resin, to all purpose putty procedure because it is not right and the areas that I applied the resin to, he painted without any sanding whatsoever and said I made a mess. Now, i have done this before and always fo a light sand making it smooth as a baby’s butt for my paint. Please somebody speak up and give me thier opinion on this. I need an honest, very much educated person on this subject to speak to me and give a good reason for me to not use this method because I find it perfect for the rotten wood and gives glass like surface for paint. Thank you very much, Lisa Catlett, self taught and very eager to learn everything about building stuff, and who loves it so very much.

1 year ago

Can a less expensive wood hardener substitute be concocted at home? Perhaps acetone and some other product?

David J Snyder
David J Snyder
1 year ago

Use a disposable meat injector to get minwax hardener deep into the soft wood so that it hardens from the inside.

Sharon McNerney
Sharon McNerney
1 year ago

I have a piece of wood that was in a lake. One side looks like the bark of a burl. The back has wood that looks very separated at the grain and doesn’t seem very hard. I’m waiting for it to dry out. Which hardener would be best to help keep the piece intact? I’m going to use water based external rated polyurethane on it for UV protection, though displaying it inside. Some feel that is enough and hardener is not needed.

Dean penk
Dean penk
1 year ago

I want to treat 30 yr old joists is what I intended to write….

Dean penk
Dean penk
1 year ago

Hi. Wood Hardner. I want to see you 30-year-old green treated joists on my deck did come in contact with water from rain. Does Hardner imply that I will not be able to nail or screw into the wood because it is hard.

Is there a better solution for refurbishing green treated lumber for another 30 years of use? Thanks in advance!

Gale Maurer
Gale Maurer
1 year ago

Can any of these wood hardeners be used on water damaged OSB?

Donna Underdonk
Donna Underdonk
1 year ago

Will any of these wood hardners penetrate through a a finish on the wood (a poly or varnish finish) or must the wood be stripped bare for the hardner to be effective?

Paul Dresher
1 year ago

Your site is amazing, such a fabulous amount of useful information. I have a question about what clear finishes can be applied OVER wood that has been hardened. I am making a low coffee-type table using out of a remnant of a large old redwood log that we milled for the extraordinary deep purples in the wood that came from lying in a gully for over 100 years. I want to make a table table (4 inches thick) that maintains the semi-rotted exterior edge and so I’m looking at wood hardeners to strengthen the shards and facets of this edge. It seems, because I want as much penetration as possible, that the MinWax wood hardener is the best choice on the edge. My question is, will I be able to put a marine varnish or epoxy (such as the Pro Marine product you rate as #1) over this once the hardener has fully drived. I also have some concern that the hardener might change the color of the surface itself, or change how the surface takes the final finish, as it is absorbed from the edges and into the main surface of the table. Can epoxy or marine varnish be applied over hardened wood?

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