be carfull on the serface side with sander or even scotchbrite/Ive seen many thing turned to junk with them.scotch brite will take materiua; off even though you dont think it is.. that plate needs to be sprayed with good oil let sit a hour, then either a eazor blade like your cleaning a window or a plastic scraper and then recoat and a good rube down with good paper towels. then you can either spray it down and store it or use it or start the real reconditioning. an dont forget the bottom is also precision!!!! , probabaly should of just sprayed wd40 or some other light oil on the bottom to losen the buildup and then paper towel clean. if the top has bumps or deformations they need to be scraped. I have 2 plates somewhat larger than that little one, they are a chore to take care of, and can be turned into scrap quickley or make a small job a large one to recondition. good luck.
Thanks for the advice. I have gone as far with it as I can, this video and the next one were shot some time ago. It really needs a regrind or scraping but for the sort of accuracy that I need it's ok.
most serface plate rust comes right off. always keep a good coat of oil on them and make a protection box for it too to keep the moistuer&debris away. I use good ply wood, be sure it's dry and coat it with oil inside, paint the out side. fit the top good so nothing gets in, add handles too it's heavy. try to keep where it will stay the same temp year long. if it gets cold then warms out side thats when the rust starts from condensation. thus the keep it oiled and try to keep moisture out, but that go's 2 ways... it can also keep the moisture in. my shop is fully heated and air conditioned. but cast iron sucks up cold and a balst of heat..... big shop door opening when high humidity or just hot as hell out like hear in florida., can make a mess of things. big things are a chore keeping rust free, like lathe beds and ways and big milling machines etc. always clean & coated. on one of my peices of equipment I no longer have, made for serfacing engine blocks&heads, I would usualy leave the cast orin fillings/cuttings on the machine for each week then clean on monday morning and re oil. the cast orin dust/debris would absorb the moisture not the machine. I was not lazy, I was protecting the machine. most machines get cleaned daily or by the job.machines with ways like my milling machines or lathers get cleaned before, during and after using. and oiled too. I think I spend more time taking care of them than using them. much cheeper and eayzer to take care and clean than to buy and replace. this stuff aint cheep. you got a great deal on that plate, give it a good usefull life again.