Sand Paper Advice?

Well I've gotten my first rudimentary (railroad track) anvil and am working on getting it cleaned up (was covered in rust, etc) and secured.

In the process I decided to try some of the wet/dry sandpaper I'd picked up the other day just to see what kind of finish I could pull off with it.

Much to my surprise, it appears the local hardware employee hooked me up with the wrong stuff despite my having asked specifically for sand paper that I could use for metal.

It sanded very nicely for a little bit, but almost immediately lost all its grit. Upon further inspection I see that it doesn't mention specifically being good for metal, and I assume it must not be designed for it.

Anyway, I was wondering if any of you folks had some advice about good types of sandpaper for this sort of work?

Thanks in advance for any insight you might provide.

Auto parts store carries the sandpaper I use for knives...

For course work try sanding linnen rather than paper. Or cut open a belt. Seems linnen holds the larger sand particles much better than paper. For fine grits the higher cost for linnen doesn't seem to pay off and i stick to paper. 3M is good for paper if your store sells it.

Rhynowet , you can find online from 80 to 1500 grit , a lot of knifemakers use it , I buy them in sheets of 50 in each grit , lasts way longer and it is actually cheaper than the Sand paper you buy from hardware store

Yes rhynowet, and make sure you get redline. They have some other lines as well that's far from as efficient on steel. But you'll be good with any quality brand, mirka is also good.

Where do you buy your Rhynowet from and do you know where you can find it online?

I get a friendly german to buy it for me and forward from a german lacquer-supplier. 123lack.de I think. Also possible from supergrit.com but shipping gets expensive from US.

Excellent. Thanks much folks!

4.5" flap wheel for a angel grinder. Works wonders for a job like this. And come in many grits from 36 and up to??

https://www.amazon.com/dp/B000WGHZYG/?tag=skimlinks_replacement-20