3 Easy Ways to Fill Cracks and Voids in Urban Wood

By Jeremy Zuleger, Urban Wood Lab Sales Supervisor


Urban wood can have cracks and voids – that’s just the nature of this incredible resource. We see a lot of customers looking at slabs they love but worry because it has a crack or void that needs to be filled. There is absolutely no reason to pass on these amazing slabs! What most people fear is having to use epoxy for the first time. While epoxy is effective for filling cracks and voids of all sizes, there are some easier alternatives when the crack or void is small. Here are three common and easy options:


#1: CA GLUE AND ACTIVATOR

CA Glue (Cyanoacrylate) is a pure form of super glue. Most super glue you purchase from big box stores has additives to make it dry faster. However, CA glue is purchased with an activator that makes it dry in a matter of seconds when applied. You simply layer in some glue, let it work its way to the bottom of the crack, spray the activator, let it harden, add another layer of glue, and repeat until you've built up above the surface of the wood. Simply sand it down and the crack is filled and it looks just like clear epoxy. CA glue comes in a variety of thicknesses and viscosities to penetrate the surface of the wood and help fill cracks completely. The only caveat is to avoid filling large cracks with CA glue. When this happens, the glue will overheat during sanding and start to gum up, making it difficult to create a smooth surface. (It also destroy the sanding belt!)


These cracks and voids were filled with CA glue.


#2: Hot Wood Glue

You can purchase wood glue sticks for your glue gun to fill small cracks. This technique is less desirable for deep cracks because the glue will often harden before reaching the bottom. Simply heat up your gun and layer some glue into the crack. Then use a flat aluminum square to press down on the glue. It will help it push deeper into the crack and cool immediately. Use a surface planer to remove the excess glue and lightly sand until you have a smooth surface.


#3: Epoxy (Yes, you can do it!)

If you do have larger voids and cracks to fill, you may as well use epoxy for all of them. Here is the best tip we can give you on epoxy: It's not as scary as you think. If you are a woodworker, you understand attention to detail. Epoxy pours go very smoothly as long as you pay attention to the details and don't skip any steps.


This crack was filled with epoxy.


You’ve probably heard horror stories about how expensive epoxy is and how difficult is it to work with. Keep in mind, these stories are often about attempts to do massive pours. A small void fill is an entirely different and much easier scenario. It's a great way to try epoxy for the first time to see if you are up for the challenge of a larger project.


The other thing to keep in mind is choosing a quality epoxy. Not all epoxy is created equal. It’s tempting to buy the least expensive brand, but the pennies saved at the point of purchase will come back to cost more down the road.

This is what cheap epoxy looks like coming through the drum sander. On average is takes 2.5x longer to sand a piece if the epoxy contains solvents that make it gummy as it sands. We have to take thinner passes with the sander and with each pass have to scrape the surface clean. (You’ll also be required to pay a fee to replace the belt.)


YouTube is filled with great tutorials on the epoxy process, start to finish. Find a channel you like to get an understanding of the process before your first pour.


At the Urban Wood Lab we’ve worked with epoxy to some extent. We are by no means experts on it, but we’d be happy to talk over your project with you!

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