how to stop wood filler from cracking?

If you’ve ever used wood filler, you know that it comes in both solid and liquid forms. Solid wood putty is often used inside furniture to fill holes or dents, while liquid wood filler can be painted or poured over a surface to create a smooth finish.

Both work well, but they have their unique pros and cons—and one of those cons is that it’s easy for both types of filler to crack with time.

Luckily, there are ways to prevent this from happening! If your wood putty keeps cracking even after it dries out completely (which can take anywhere from 24 hours to 72 hours), follow these tips:

Why did my wood filler crack?

You’ve just spent hours sanding and filling the holes in your woodwork, but when you come back to admire your handiwork, it looks like you’re staring at a face full of wrinkles. Why did my wood filler crack?

If you’re new to woodworking (or even if you’re not), one of the most common questions people ask about filling is this: Why does my filler crack?

The answer depends on what kind of filler you’re using—and sometimes even on which brand of that kind of filler.

Wood fillers are usually made from two different materials: polyurethane and epoxy. Both are effective in their own ways; however, they can both be prone to cracking over time if exposed to too much moisture or high temperatures (like those found in direct sunlight).

This can cause them to dry unevenly around areas where they were applied too thickly or with low-quality application techniques by someone who doesn’t know how best to use them properly without risking cracking due to damage caused by improper application techniques used during application process itself.”

How do you fix cracked wood filler?

  • Use a putty knife to remove the cracked filler from the surface of your project. If you can’t get it all back in place, use a wet rag to wipe off excess filler and let dry completely before sanding.
  • Sand the area with fine sandpaper until smooth, then apply another coat of wood filler (and let cure).

Why does my filler keep cracking?

  • Too much filler
  • Filler is too thick
  • Filler is not sanded enough
  • Filler is not applied to a clean surface
  • Filler is not applied to a dry surface or at least allowed to cure for 7 days (or longer) before painting
  • Applied in cold weather, which can cause cracking.

Does wood filler crack over time?

Yes, it will. The main reason why wood filler will crack over time is that it’s not as strong as the wood it’s used to fill.

If you’ve ever tried to cut through a piece of lumber with a sharp knife, you’ll know that it takes quite a bit of pressure—and often some help from a saw—to get through the outer layer of the material.

Because this outer layer is what makes up most of your finished product, you have to take special care when applying filler to your project so that you don’t apply too much pressure and risk cracking it.

How long does wood filler take to harden?

The length of time it takes for wood filler to dry depends on a variety of factors, including the amount of moisture in the air and how much ventilation there is around your project.

In general, you will want to wait at least 24 hours before sanding or painting over your work – but this can really vary depending on what kind of wood filler you are using.

  • Dry Time: The amount of time it takes for a glue-like epoxy or polyurethane resin will depend on how thickly you apply the glue and how much ventilation there is around your project. In general though (especially with thicker applications), be patient! It may take 48 hours or even longer before all those layers have dried completely through their cycle before they can be handled safely again without getting stuck together when handled aggressively during application.*

Do you need wood hardener with wood filler?

You don’t need to use a hardener with wood filler. Wood filler is already very hard, so you won’t need to add another layer of hardness to it.

However, if you’re applying the wood filler over an existing surface that was not properly sanded, then there may be some situations where a wood hardener is needed.

If this is the case, only use it sparingly so that you don’t create a thick layer of hardened material on top of your workpiece.

Will linseed oil stop wood from cracking?

You might have heard that linseed oil is a wood hardener, but it’s actually a preservative. That means it helps protect the wood from moisture and air, but it won’t stop cracks from forming.

In fact, using too much linseed oil can cause your wood to rot faster than normal.

It’s also worth noting that linseed oil will not seal any cracks in your wood filler—and if you try to use it on top of cracked filler, you’ll end up with an even bigger mess on your hands!

Are wood putty and wood filler the same?

You might have heard the term wood putty used to describe a type of compound that’s used to fill holes and cracks in wood.

While there is some variation in how these products are manufactured, they’re essential all the same thing: they’re designed to fill holes and cracks in wood.

However, many people use the terms “wood filler” and “putty” interchangeably when it comes to filling gaps with compounds.

Putty is sometimes used for other purposes as well, including plugging screw holes or gaps in furniture pieces like drawers and cabinets.


We hope you’ve found this article helpful. If you have any more questions about how to stop wood filler from cracking, please feel free to leave a comment below and we’ll get back to you as soon as possible!

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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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