Live edge slabs are super popular right now. From river tables to leaving the slab whole, it shows off wood’s natural beauty. But working with live edge slabs can be somewhat of a pain. They are big and bulky, which makes moving them by yourself very difficult. Using traditional machinery is also somewhat of a challenge because nothing about a slab is straight and square.
We are not professional live edge furniture makers, but here are some tips to help you with your live edge projects.
Start With a Kiln Dried and Heat Treated Slab
The kiln-drying process removes all of the excess moisture. At certain temperatures, the wood is sterilized from any bacteria and pests. Fresh cut lumber contains a ton of moisture. Because wood shrinks as moisture is removed, the excess moisture needs to be removed before the lumber is turned into a product. If the moisture isn’t removed before getting turned into a product, the wood will slowly lose moisture and shrink. If this movement isn’t accounted for, the wood can check, split, and crack.
Slabs often come from salvaged logs. Logs that could have been killed by disease or don’t have any high-grade lumber. These logs might have sat around for a while before being sawn, and as most people know, there are lots of bugs that love raw wood. The easiest way to kill any pests or bacteria is by heat-treating the wood (133°F core temperature for at least 30 minutes) during the kiln drying process. No one ever wants bugs crawling out of their finished table or bar.
Get It Flat and Keep It Flat
Since most live edge slabs are too wide to fit through jointers and planers, getting a slab flat can be quite a daunting task. Some suppliers have the equipment to flatten slabs. We suggest trying to find a slab that is already surfaced. It will save you a ton of hassle and time. But if you can’t find a surfaced slab, you can flatten it with the router sled or by hand.
You want to try to keep your slab from twisting or cupping after it’s been machined flat. Pay close attention to the movement of the slab. The slab is most likely to move before a finish is put on. Either allow air flow on all sides, or cover up both sides to not allow for any air movement. If you find your slab cupping, don’t freak out. Flip it over and let airflow over the bottom (now top) face. You can also take the extra measure to flip the slab over every couple of days. This will even out the moisture exchange on both faces of the slab and should keep it flat until it’s finished.
The last tip to keeping a slab flat is during the finishing process. Apply the same number of coats of finish to both sides of the slab to even the moisture exchange on both surfaces. It’s also not a bad idea to get both sides of the slab finished on the same day, especially with the first coat. Finish slows moisture exchange, and the wood absorbs the moisture from the finish. So if you’re not careful, a slab can cup just by applying finish to one face one day and then waiting until the following day to finish the other side.
Track Saws Make for Easy Work
As mentioned before, live edge slabs are anything but straight and square. Most shop equipment requires at least one square edge. Feeding the material through the machine safely and creating a straight edge (if needed) can be dangerous if you try to use a jointer or a table saw with a jig.
The best way to get a straight edge on a slab safely is with a track saw. A track saw is a pretty simple piece of equipment. Essentially, it’s a circular saw and a straight edge that has grooves for the circular saw to ride in. Instead of bringing the wood to the tool, you bring the tool to the wood, eliminating any issues you might have with moving the slab. This makes for quick and effortless work.
The only downside to a track saw is the price. If you cannot justify the purchase of a track saw, you’re not out of luck. Go ahead and use a circular saw and straight edge. Getting things lined up perfectly can be a little more difficult, but it makes for a great option for someone that doesn’t want to purchase a track saw. There are also plenty of DIY videos on how to make your own track saw.
Use Resin (or Epoxy) to Fill Any Defects
Not all slabs are clear, and actually, it can be kind of difficult to find a slab that has no defects. So how do you work around these defects? Well, instead of working around them, just embrace them and fill them with resin. The only word of caution here is to make sure you remove any bark or unsound wood (rot, loose knots, etc.) before you pour any resin. Bark and unsound wood absorb finish differently than sound wood. This can cause problems with some finishes, especially oil finishes. The bark and unsound wood will absorb more oil finish and will create an uneven sheen in the finish.
Prep for Any Resin Work
Before you mix up any resin, you want to make sure you’re prepared. You’ll want to cut the slab as close to the final size as you can. Resin is expensive, and you don’t want to waste any by pouring extra resin in the over-length of the slab. The resin will bond to anything and you won’t be able to break that bond after the resin is cured.
If you are doing just a little bit of resin work, you can probably get away with taping the undersides of the voids with house wrap tape. The resin will not bond to this type of tape, which makes it great for this purpose. The only key here is to make sure there is a great seal between the tape and slab.
When you’re doing a larger pour or a river table, you’ll have to build a mold. Once again, you’ll have to take measures to make sure the cured resin will release from the mold. You’ll need to coat the mold in mold release or line it with some house wrap tape. Also, caulk the seams with silicone to make the mold waterproof.
Wood floats when you pour resin around it. The wooden pieces need to be either clamped or screwed in place. After you poured the resin, you’ll want to pop the bubbles. Some resins cure slow enough to allow the bubbles to pop themselves, but others have to be popped with a heat gun or blow torch.
The last thing is making sure to keep everything clean. This can be challenging in a shop but is very crucial in the results of the pour. Dirt will float and get trapped in the resin. This might not be a super big deal if the resin is tinted solid black, but most people don’t want to see sawdust, bark, or dirt floating in the resin. Not only will it be less appealing, the dirt, dust, and bark can also affect the bond between the wood and the resin. Make sure to vacuum, wipe, and blow any dirt out of these areas.
Keeping airborne dust to a minimum is also important. As the dust settles, it will land on the curing resin. This will produce a bunch of speckles/spots in the finish of the resin. To avoid this, you might consider waiting a day to let the dust settle before pouring the resin, pour and let the resin cure in a different room/area, or put a plastic tarp/sheet over the curing resin to prevent any dust particles from falling on the piece.
Sand to Perfection
One of the great things about sanding wood is it hides sanding imperfections in the grain. But resin is the exact opposite; it shows everything. It will show if you skipped a grit, or your sander left scratches on the surface. So you need to follow a pristine grit sequence and make sure you have great dust collection. If you don’t have a dust collector hooked up to your sander, you’ll want to take a few extra steps (even if you do have dust collection, these steps wouldn’t hurt).
Make sure the sandpaper is staying clean and isn’t getting clogged up with dust. Every couple of minutes, stop and blow out the paper. Instead of polishing the surface, the clogged paper will put more scratches into the piece.
You’ll also want to follow behind your sander and wipe the surface with a clean cloth. This will pick up any dust that might accumulate and scratch the surface.
Resin takes a lot of time sanding to get a nice polish. Normally, it needs to get sanded 400 grit before you can no longer see the scratches from the sandpaper.
Our last tip is to be cautious how much material you are removing while sanding. Resin is harder than the wood slab. This means you will remove material quicker from the wood than the resin. If you’re not careful, the surface will become wavy, low in the wooden spots and high in the resin spots. To avoid this, spend more time sanding the resin and keep feeling the surface with your hand to ensure it is staying flat.
Know the Limitations of Finishes
All finishes have pros, cons, and limitations. The biggest thing to note is what grit the slab is sanded to. If it is sanded above 220 grit, you need to use an oil finish. At 220 grit, the surface is too polished for finishes like polyurethane, lacquer, and varnish to stick to. But oil finishes have their weaknesses too. Not all oil finishes produce a super hard durable finish, and some require special maintenance. So do your research and select a finish that meets your needs.
Just like any woodworking project or piece of furniture, live edge slabs have their challenges. But when you take precaution and the proper steps, the project will normally turn out the way you envisioned. Let your imagination run wild, and turn that somewhat “ugly” looking slab into a masterpiece!