It's been way too long! We had a minor catastrophe at home and we've been dealing with two bathroom renovations, so that's pretty much taken away my woodworking time. On the plus side we'll have two new, modern bathrooms that meet our tastes. So, it's a win in the long run!
Me being the way I am, I couldn't possibly complete a renovation without somehow working in a woodworking project. The upstairs bathroom was no different.
I did my homework on live edge vanities and decided to give it a go. My first concern was durability of the vanity as a whole and making sure that the finish on the slab would hold up. Luckily I've used waterlox in the past and after some reading I was certain that would be my best option, provided I do enough coats.
We needed a vanity with storage so the next question was whether or not to build a vanity or repurpose one. The decision was made to purchase a vintage dresser or credenza and put the slab on top of that. Plus, I'd yet to do casework and was leery of my first cabinet going in this bathroom. After some searching we found something very close to what we were looking for at www.midcenturyfurniturewarehouse.com/.

The credenza and slab. We ended up going
with a smaller sink in the end.

Next was another case of my being antsy to get a suitable slab. I went to my usual sawmill and looked at some walnut slabs. The supply was pretty limited at the time, and rather than wait I instinctively bought one I thought would work.
Of course, in my haste I neglected to notice that through the middle of the slab the width curved in a good amount. As it turned out, through the middle this slab was maybe 2"-3" too narrow to cover the width of the cabinet we'd gotten. I was pretty upset over this because I knew I'd goofed up and we'd already spent a good deal on the cabinet. So what I decided to do was split the slab lengthwise and drop in a plank of cherry. I had never used cherry, nor done a glue-up, so here was my big chance.
I went back and got a cherry board and then it was time to get cracking.

Flattening with a
router sled.

First, as usual, I had to surface the slab and do my butterfly keys, since this slab had some sizable checks. I used rosewood for my butterfly keys since I think they look the best with walnut. After that it was time to decide where to cut the slab lengthwise. I decided off-center would look cooler and more modern so I went with that. Then I went about squaring, surfacing and planing the cherry board.

One of three rosewood
butterfly keys I added.

Next, it was time to joint and edges of the slab where I'd cut it. First I attempted to do it on my jointer but that proved too difficult with the length of the slab and maneuvering the uneven top edge.
Then I tried a simple circular saw straight jig, followed by a jointer plane. I wasn't thrilled with those results either. Finally, I clamped a long piece of melamine to the top of each piece of the slab and used a top bearing router bit to joint the edge. This technique ended up working great and I really recommend it for jointing long boards. Just be sure your melamine (or plywood etc) has a clean edge and that you do not rock your router at all.

Jointing with a router.

My first-glue-up went pretty smoothly actually. Aside from a little unevenness between the cherry and walnut I was happy. I was going to have to resurface the top anyway.
Now for the fun and-or scary part: since this slab was topping a cabinet in a bathroom, I thought leaving those checks open in a wet environment would be pretty stupid. There was little chance water would never get in there and into the cabinet. So I did some research on people who'd used resin to fill checks in slabs. I ended up getting a clear resin from these guys, www.artstuf.com/.
This was my first foray into using resin so I was nervous. I didn't want to mess up this slab or have checks in it either, so this had to work the first time. I knew I had to do a great job of closing up the bottom side of the cracks so I wouldn't have any leaks. I also had read about heating the resin with a hair dryer to try and minimize the formation of air bubbles inside it.
So, I taped the hell of out the bottom side of the checks, the ends of the slab, and around the edges of the checks on the top with painters tape. I mixed my resin and started... About 15 minutes in, I started to see both sides dripping out the bottom; one side was dripping every few seconds and the other, maybe every 10 seconds. I was panicked. I did what I could to use some more tape to try to slow or cease the drips. It turns out the edges of the slab were too rough for painters tape to create a great seal. I should have noticed that. So the resin was creeping out the end and out the sides of the tape. Re-taping slowed the dripping a bit, as did the eventual drying process of the resin. I had to come back the next day and add more but in the end it worked. I let the resin cure another day and prepared to sand it off. Luckily it sands pretty easily. Getting the tape off proved to be a pain so some was simply sanded off. I treated the resin just like wood in that I started with a low grit and worked my way up.

Prepped for my first try at using resin.

The only thing I did differently with this top was sand it to 800. I'd read that in order to get a decent smoothness and clarity to the resin you have to go high with your sanding. I used 3m wet/dry sandpaper.

So after that it was basically just doing my waterlox routine. As far as attaching the slab, I allowed for movement using a slot cutting bit before screwing in through brackets on the underside.
So, it was a fun project. I got to do a few new things and learned some things. I'm happy with the results and like having something a little different in our bathroom.

The finished top with the sink installed.