Refinishing wood workbench

Hello!

I've got a butcher block top on my toolbox and I'm looking to refinish it. It came with a sort of finish on it when new, and I applied several extra coats of varnish before putting it into use. The top is a couple years old now and has seen lots of use (I'm a tech at a dealership) and I'd like to clean it up and re-protect it again. My additional varnish hasn't held up all that well, there's a couple places where brake fluid and a few other fluids have peeled up and/or softened it, but the factory finish under that has held up to the fluids in the places where the varnish has peeled off. I'm going to be renting a belt sander and taking it down until it looks good. I think I'm going to try and just take off the varnish I put on and not go through the factory finish. Once I've done that, I'm left with deciding what to apply back on it.
Doing some googling has led me to this, polymerized tung oil but most results I'm getting are from woodworking sites and I'm not sure what works in someones hobby woodshop will hold up in a daily automotive environment.
Any suggestions on what I should use? The top is made of maple I believe.

Place where brake fluid sat for a bit and peeled off.

Bar top style clear epoxy would be my first choice.

It is HIGHLY likely that the original finish was polyurethane.

Your varnish didn't bond well to it, because varnish is a soft penetrating finish, and plyurethane is essentially a hard plastic (like) coating that sits on the surface. The varnish would only bond if you had sanded very well between coats (giving the varnish some rough edges to bond to). But it still wouldn't stand up to the abuse you are giving. It's a penetrating wood finish. You are looking for a hard plastic sealer.

Tung oil is also a soft penetrating finish. Beautiful and great looking, but not as durable.

I really think your best bet is several (4 or more) coats of good ol' polyurethane.

It's unlikely you will sand only the varnish without also sanding through the poly underneath, but if you do succeed, the poly will stick just fine. Varnish or tung oil will not (unless you sand the poly completely OFF).

Ian's right- pour in place epoxy finish would work well too (a bit more difficult), but you REALLY should sand the poly completely off.

BTW- brake fluid is super nasty. Wood finishes aren't really designed to resist it.

Here's a silicone epoxy that is designed to stand up to it, but the price might exceed the value of the bench:

Silcone epoxy finish that can stand up to brake fluid

Yeah I didn't realize the brake fluid was leaking in that spot, normally I'd wipe it off as soon as I could. I'm about to leave for home depot and find some polyurethane coating and rent a belt sander, I'm trying to do this in the next week or so, so shipping stuff I'd like to avoid. That does look pretty sweet though. A new top is about $300 so making this one last is worth it.

Make sure you have sandpaper for between coats. I think 220 should work. Hopefully Svrex can confirm before you get started. Plan on this taking a few days once you sand off the old varnish. It's hard to speed up the drying times. Not a difficult project. Just a bit time consuming.

Welp the belt sander made real quick work of it.
Before:
After:
Lighting + camera phone makes it look funny.
Still have to do the edges and stuff, but I'll be doing that by hand. I've got another 4 weeks to finish the project, so I've got lots of time to let coats dry, no rush.

A friend managed to snag 3-4 butcher block maple bench tops from a local high school that was being renovated, and gave me one. It was about 4x6 feet, nearly 3" thick and the short ends were slotted for an angle iron cross brace. It weighed well over 200 pounds.

I ripped it in two w/ a circular saw, planed the cut edge smooth, and cleaned up the face with a belt sander starting with 36 grit, progressively moving to 120. I finished with a 1/4 sheet orbital w/ 220.

For a few weeks after the bench was finished I swabbed on a wet coat of Watco oil every day w/ 4/0 steel wool. Now I do the Watco and steel wool about 1-2 times a year and it looks fine.

"Before" is prettier, IMO.

Watco Danish Oil finish is a beautiful finish. But again, it is a penetrating oil and varnish.

The OP is looking for something he can spill automotive fluids on. Using a penetrating oil finish to prevent oil from penetrating isn't gonna work.

It LOOKS great. But it is not designed for an automotive application.

I have a gorgeous wood workbench with an oil finish, but it is only used for woodworking. I'd be really upset if I spilled oil on it.

I specifically meant the oil stains look good. People who make good money pay me good money for 100 year old wood that's beaten, battered, naturally stained, etc. Just throwin my two pennies in.

Honestly, I might mix up some polyester epoxy resin and pour it on/apply with a paintbrush.

If you want to save a bit of time and trouble, you could just wrap or cover the wood with a thin sheet of aluminum.

Great, now I want a bench top like that.

Personally, I am a fan of wood that looks like it has been through Hell. Gives it character and reminds me where it has been.