Woodworking with large live edge slabs can result in beautiful furniture pieces, assuming nothing goes wrong. In this blog, we’re going to breakdown the most common issues we see with live edge slabs.
#1 – The Slab Warping
This is by far the most common issue we hear with live edge slabs. This can happen for a number of reasons. Those reasons include:
- The slab wasn’t dried right in the first place. Though not super common, it is worth mentioning. If a slab isn’t dried enough it will warp as it dries out more once it’s in a home.
- The slab wasn’t finished and it was stored laying flat or with uneven exposure to each side. If a slab, for example, is sitting flat on a floor, then moisture can absorb or escape from the top. This change in moisture unevenly on the slab would cause the wood to warp.
- Applying a finish on one side only or unevenly. If one side traps moisture and one side absorbs it, expect warping to occur. If you’re working in a garage or woodshop, and you only finish one side, slabs can warp as quickly as overnight. To avoid this, cover the one side you didn’t finish with blankets and finish the project as quickly as you can.
- The slab wasn’t stored in a good location. Locations such as bathrooms or basements that have high moisture levels in the air are not ideal. Garages or storage units are also not ideal unless they’re heated and have dehumidifiers.
- The slab was transported with stress on the wood. For example, if you transport a 12′ slab on a truck with a 6′ bed, good chance it can warp by the time you get it home.
- The slab was left outside and it rained or was exposed to high temperatures and sunlight. This can cause warping within hours.
How to avoid warping:
Warping is usually avoidable. The best things you can do to keep your slab from warping are:
- Store it upright after it’s flattened, not laying down.
- Store the slab wherever it’s going to be used as a table for 1-2 weeks before finishing it. The slab will adjust to the moisture content of the location it’s going. Changes in moisture content are what cause the slabs to warp the first place.
- Check the moisture content before buying. If you’re in PA or Maryland, we recommend slabs that are dried to 12% or less throughout. If they are not, store them in your house as recommended above before finishing.
- Cover them with moving blankets and support the entire slab evenly when transporting them.
- Keep your table away from areas of high heat such as floor vents and other heaters such as wood burners.
- Don’t use live edge in areas such as cabins unless they are temperature controlled year-round.
- Mount the slab to a base. Don’t just sit it on one – actually mount it.
What if the slab already warped?
If the slab already warped, there is a good chance it’s still a chance it’s not ruined. When this happens, you can flip the slab over and often it will take back it’s original shape within a few days. If it doesn’t, you may need to flatten it again.
#2 – The Slab Cracking
The second most common issue is a slab cracking. This can also usually be attributed to changes in humidity and temperature. This typically happens at the kiln or while the slab is air drying. However, it can happen once a table is mounted to a base.
A fact with all wood is that it moves. It expands and contracts in different environments. If your slab is mounted in a way that doesn’t allow for the wood to expand and contract like it wants to, there’s a high probability that it will crack.
A few tips to avoid cracking
There are a few things you can do to help keep your slab from cracking:
- If you’re using a metal base, be sure it has slotted mounting holes, not round ones. When the mounting holes are slotted with across the grain of the wood, it’ll allow the wood to naturally expand and contract. If the wood can’t move, it will crack.
- Use threaded inserts to mount your legs. Be sure these are perfectly centered on the leg slots.
- If mounting to a wood base, choose a mount that allows for wood movement across the grain.
- DO NOT mount using screws. Screws can typically be used for very small pieces, but you will likely run into issues if you use screws to mount larger tabletops.
Bonus tip for avoiding cracking and warping:
Cutting the slab down the middle and using domino joints and wood glue to put it back together can remove the stress on the pith of the wood. This can help to alleviate many of the common issues.
You can also use multiple slabs on your top, which is known as a bookmatch. Bookmatching is a great tactic for making a live edge table with any size and shape. This also makes the wood more structurally sound than buying a large slab for your top, which is why it’s often preferred. Rip cuts with the grain of the slab relieve tension and decrease the probability of your slab warping.
#3 – Soft Spots & Holes in the Wood
Soft spots can often appear in wood in areas of rot or where there are bug trails. If you’re wood has little powerdery holes, there’s a good chance it’s a powderpost beetle. Often these trails are right below a thin layer of wood, and can lead to a weak spot. They’re typically toward the edges of the slab.
If this is an issue, there is a few things we recommend. For large holes, you’ll want to fill them with epoxy resin. Once it cures, the epoxy will strengthen the wood. For smaller voids, we sometimes use starbond, which is an adhesive designed to fill voids and cracks on wood.
Whichever route is easiest is better than doing nothing. Tabletops are often areas of high wear and tear, which is why we recommend filling any voids in the top of the piece.
Soft spots may also appear from rot. If this is the case, oftentimes it’s best to remove the rot and fill the void with epoxy resin. These fills the rotted area and forms to the shape of the void, making it a great way to solidify a tabletop.
Questions About Common Slab Issues?
The issues mentioned in this post are extremely common for even experienced woodworkers. If you have any questions before purchasing a slab, please drop them in the comments below or ask before you pickup you wood slab!