Arm-R-Seal is an oil-based urethane. You wouldn't want to use a polyurethane over it; you're essentially finished. 3 coats of that stuff should be fine, adding any more is kind of unnecessary. The only time you add more layers of finish is when you're working with tung oil, shellac, or high-end finishes like conversion poly/lacquer.
Your best bet would be to possibly shine this up with some Johnsons Paste Wax that you can buy at Lowes or Home Depot if you don't use Amazon. Wait a week or 2 to let the finish gas off, and dry up a bit more, and use this paste wax every 6 months to a year. It's been around forever, and works really well.
Edit - If you haven't, make sure you've sealed the bottom of the butcher's block as well. You don't want one side sealed, and the other unsealed; granted, this type of butcher's block with multiple pieces glued together will not move as much as a panel glue up would, but it's still a good practice to always finish the bottom as well.
Here is what I do. 1. I take a flexible putty knife and scrape off the surface rust.
If you are lucky and that gets most of it I would use some 600 grit paper and a random orbit sander to sand the surface. That fined of a grit will not change the flatness.
If you are not that lucky. I use some 400 grit wet or dry paper (the black stuff) and some WD 40 and I hand sand the surface using a block of wood. Once I got most of it clean I would wipe it down and use the 600 grit paper.
Apply a layer of SC Johnson's paste wax in the yellow can. It is solvent based rather than water based like a lot of car wax compounds. If you are going to use it soon apply the wax let it dry and buff it off. If the tool will sit for several weeks between uses apply the wax let it dry and buff it off just before you use the tool.
SC Johnson Paste Wax The kind that is solvent based not water based like most car waxes.
I also use it on all of my hand planes, chisels, etc. in order to avoid surface rust on them. If I plan on not using the tool for a few weeks I put on a thick-ish layer of wax, let it dry and buff it off just before I use the tool. Otherwise I apply the wax and buff it off right after it dries.
More important than that I have a wooden cover that extends over the surface of all of my shop tools with steel surfaces. In some cases like my planer and bandsaw it is thin-ish plywood with a few strips tacked on in order to keep it in place. For my table saw it is a chunk of repurposed solid core door that is about 1.5" thick. This gives me a good auxiliary work space where I do not have to worry about a few drips of paint or what ever.
Awesome!! Same with me....my wife bought it for me last year and what a nice saw indeed.....if I can suggest you get SC Johnson Paste wax for your work area....this keeps it clean and super smooth....it also protects it....here is a link on Amazon amazon.com/SC-Johnson-Paste-Wax-1lb/dp/B0000DIWIM
Best of luck and Happy Holidays!!
Possibly, but why bother, honestly, regular past wax is sufficient. I can see rolling your own wax for finishing work as it can make a difference, but for rust prevention....... $11 sort of makes it easy.....
https://www.amazon.com/Johnson-Fine-Wood-Paste-00203/dp/B0000DIWIM
After refinishing old tools using electrolysis to remove all traces of rust, I've had good success using (Johnson's Furniture Wax)[https://www.amazon.com/Johnson-Fine-Wood-Paste-00203/dp/B0000DIWIM] to rub into to the metal to protect it.
Some items I get very hot with a torch then rub oil into the metal. This works similar to seasoning a cast-iron pan.
In general, I'm sticking with the furniture wax. It's easiest and provides a good sealing finish. (I didn't come up with this, I did the research after deciding to remove rust using electrolysis.)
I work in an Ornimental metal shop. For things like this that don't get abuse by weather we almost always use Johnson's Paste wax. Most clients only need to apply it once a year.
I just use plane old Johnsons Paste wax. Might be better stuff out there as already mentioned in this link. Here's what I used last weekend: http://www.amazon.com/Johnson-Fine-Wood-Paste-00203/dp/B0000DIWIM/ref=sr_1_sc_1?ie=UTF8&qid=1421962287&sr=8-1-spell&keywords=johnsson+paste+wax
sounds like it could be tinted paste wax. Easy fix for them, not a particulrly protective or durable solution unless the varnish beneath is in good shape. If they waxed freshly sanded flooring, I would recommend stripping the wax (mineral spirits wash, etc), then applying several coats of polyurethane.
Wax wax wax. Grab a can of Johnsons Paste Wax and give your bed and in/out-feed tables (if you have them) a nice coat or two.
You got some old inventory stock. When you see it on Amazon for $28 a can, you know the sharks are out there . . . https://www.amazon.com/SC-Johnson-Paste-Wax-1lb/dp/B0000DIWIM
A scotch brite pad and some of this johnsons paist wax should fix it right up. Try to always keep a little bit of the wax on the surface and you should be good going forward.
Paste wax. It works great, isn't tacky, slippery or sticky, and lasts a long time. It's what I've used on my tools for years now. I started after using electrolysis for rust removal on an old bench vise.
I have this can, I think. But any paste wax should work. https://www.amazon.com/SC-Johnson-Paste-Wax-1lb/dp/B0000DIWIM
Inletting Action screws https://www.brownells.com/gunsmith-tools-supplies/stock-work-finishing/stock-making-accessories/inletting-guide-screws/inletting-guide-screws-prod6644.aspx
Johnson Paste Wax https://www.amazon.com/Johnson-Fine-Wood-Paste-00203/dp/B0000DIWIM
Modeling clay https://www.amazon.com/gp/product/B000ICK046/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
This. Johnsons paste Wax.
Johnson Wax 16 Oz Fine Wood Paste Wax 00203 https://www.amazon.com/dp/B0000DIWIM/ref=cm_sw_r_cp_api_5xmxxbEA4SRFM
I use Johnson paste wax.