Woodworking questions on stabilizing cracks

So I'm going to make another couple of slab tables and have a few questions.

Question 1: I bought two dried and flattened redwood slabs yesterday and they have some medium cracks that I need to stabilize.
Are bowties necessary or should I just use epoxy (I'd prefer NOT to make bowties)? I have West System resin and hardener ready to go.

Question 2: For sealing the table, I want to try epoxy for a more durable finish, then sanded with high grit to remove the gloss.
I've read a lot about high temperature (70ºF or more) being critical to curing the epoxy. Can I do this in San Francisco weather?
What brands of should I consider? Even within each brand there are a million options so specifics would be great.

Any more tips or suggestions would be much appreciated.
Thanks!
Andrew

If you haven’t seen his channel already, check out Blacktail Studios on YouTube. That guy is a god of a slab furniture maker and share so many amazing tips, as well as the brands of products he uses. I’ve gotten lost in his builds for hours.

As far as the dovetailing, I think there’s always a risk the crack will proliferate if it’s not managed, but I bet the epoxy does the job as long as the gap isn’t huge. Hard to say without a pic. I am no expert but I have an opinion and an asshole just like everyone else 

If you haven’t seen his channel already, check out Blacktail Studios on YouTube. That guy is a god of a slab furniture maker and share so many amazing tips, as well as the brands of products he uses. I’ve gotten lost in his builds for hours.

As far as the dovetailing, I think there’s always a risk the crack will proliferate if it’s not managed, but I bet the epoxy does the job as long as the gap isn’t huge. Hard to say without a pic. I am no expert but I have an opinion and an asshole just like everyone else 

Yes, Blacktail is great, but there is just so much content to wade through.
The gaps aren't huge, don't even go all the way through. I'll try and post pics. Thanks!

As I posted In the other recent thread, I’m also about to work redwood slabs.  I plan to cure the epoxy at 80° or so using a heater.  Heat is important.

On the checks on my slabs I made pencil marks at the ends of the checks to see if they grew while the slabs dry. None of them did.  Mine are all very minor, there’s six of them. I’m not planning to bow tie them.

West Systems will bind it no need for dovetails. Do some research and a test to find out the best way to get the bubbles out. Another option is to add graphite or other tint to the epoxy then you won't see the bubbles.

You will need to heat up a room or build a small heated enclosure and preheat the material and the epoxy above the recommended temperature. A temperature gun is very helpful and be careful of large volumes of epoxy self combusting.

As Tsuri says, use West System 2 part epoxy, then tape the top and flip the slab over, bubbles will float to the underside of the slab leaving a nice smooth , bubble free finish on the top surface.

As I posted In the other recent thread, I’m also about to work redwood slabs.  I plan to cure the epoxy at 80° or so using a heater.  Heat is important.

I've heard mixed things about this point. Some people I've talked to say they cure epoxy at lower temps all the time, that it cures properly, but just takes longer.
How critical is heat? This is San Francisco weather, I don't have a space heater, and prefer not to use a heater at all to avoid high costs.
Are there any lower temp epoxies for cold weather? Anything like that?

I've never done a redwood slab, but did finish a rough-cut madrone slab about 10 years ago--lots and lots (and lots and lots) of sanding, then coated it with epoxy.

I live in the Santa Cruz mountains, and didn't use any heat source for curing. Heat is important if you are looking for maximum strength in a fiberglass build, but I don't think it is a significant issue for a table top, as long as you stay within the recommended range for the epoxy you're using (I used West System).

A hair drier helps with bubbles but, if you can muster the nerve, the superheated gas from a propane torch is much more effective. I ended up with a few spots where bubbles rose throughout the cure process. It seemed there was some sort of reaction with the wood itself. That was kind of annoying, but pretty minor overall.

Madrone is notorious for twisting, and yet in 10 years, I've only had to repair one small area.

Finally, I would just pour to fill any cracks, as others have suggested.

Heat is important if you are looking for maximum strength in a fiberglass build, but I don't think it is a significant issue for a table top, as long as you stay within the recommended range for the epoxy you're using (I used West System).

That's just it, though. The recommended temp range for most tabletop epoxy is over 70, and I don't have that available (unless I crank the heater $$$). So what should I do? My fear is that it winds up never curing or something. That it stays tacky and doesn't dry.

I’ve worked with a bunch of different epoxys in both boat repair and rod building. West was actually pretty easy to work with, some are super temperamental.I’d reccomend staying within the temp range at all costs . One tacky, gummy, sticky, cloudy, coat will result in a ton of sanding, second guessing and kick yourself in the ass internal monologue cause you know better lol.  I’d rather pay the heating cost than going  through a do-over……plus heating costs.

When I painted my boat over the winter I tented it and bought a forced air heater to maintain 8 hours of cure temp over 55.  Wound up only running it in intervals and it was keeping 70+ temps in cold ass weather.  You could probably throw that slab in a vented tent outside with an infrared or small camp heater and be fine.

I’ve worked with a bunch of different epoxys in both boat repair and rod building. West was actually pretty easy to work with, some are super temperamental.I’d reccomend staying within the temp range at all costs . One tacky, gummy, sticky, cloudy, coat will result in a ton of sanding, second guessing and kick yourself in the ass internal monologue cause you know better lol.  I’d rather pay the heating cost than going  through a do-over……plus heating costs.

When I painted my boat over the winter I tented it and bought a forced air heater to maintain 8 hours of cure temp over 55.  Wound up only running it in intervals and it was keeping 70+ temps in cold ass weather.  You could probably throw that slab in a vented tent outside with an infrared or small camp heater and be fine.

Thanks for the tips. I'm thinking of using just polyurethane, after filling the cracks and holes with West System epoxy.

I used polyurethane on my last one - 7 coats - and it really is quite durable.
Epoxy pouring looks messy and quite intimidating.

Here is the crack I was referring to. It's quite long, but doesn't go through the wood. I've seen videos on YT of worse cracks than this being filled with epoxy, no bowties.
Question: once the crack is filled, will an epoxy top coat add more stabilization to the cracks? Or can I use polyurethane (or something lighter) at that point?

That's just it, though. The recommended temp range for most tabletop epoxy is over 70, and I don't have that available (unless I crank the heater $$$). So what should I do? My fear is that it winds up never curing or something. That it stays tacky and doesn't dry.

West System 207 (special clear, which is what I used) has a minimum temp of 60 degrees:

https://www.westsystem.com/207-special-clear-hardener/

Their 205 hardener can be used down to 40 degrees.

In any case, if it is going to live indoors, I'd go with polyurethane. As you say, it is much less intimidating, and far more forgiving if you make a mistake--just sand a bit and do it again. And, I wouldn't even bother with epoxy to fill a crack like that, as the PU will seep into it.

Blacktail studio on YouTube has lots of good tips for finishing slabs

I have an old growth redwood table that has been in my family for over a hundred years from the Santa Cruz mountains. I took it apart planed and sanded it down to restore it and found some cracking in the wood. Bow ties are defiantly a great way to go. I had to put two in the look great as accent pieces and also for stability. Redwood is so soft that they are easy to cut in. Cut the bow ties first then trace them onto the slab, rout out the traced line leaving about a 1/16” -1/8” then take your time with the chisel. It’s worth it. Epoxy I have no experience.  I used an oil and let the dents happen. Have fun