On Fri, Mar 28, 2014, at 08:20 PM, andy pugh wrote: > On 29 March 2014 00:01, Pete Matos <petefro...@gmail.com> wrote: > > I would not recommend putting anything on your plate that can build up at > > all.
I agree, if the plate is going to be used for measuring. The original poster wants to use it for photography as well. If he really needs a shine, he has two ways to get it: 1) use very fine abrasive and polish the plate. That is guaranteed to remove at least a little material. How much I don't know. Enough to affect accuracy? Maybe. I think it would be hard to polish a uniform amount off everywhere, so flatness would suffer. Not a good plan. 2) apply something that will fill the very fine scratches that are the difference between matte and shiny. Could be a splash of water, but that will dry and go matte again quickly. Could be some kind of oil, would last longer and still be easy to remove with the right cleaner. Or could be automotive paste wax. In any case, he will need to buff it with a soft cloth so there is a negligibly thin layer over the surface of the plate but it fills the scratches. Do NOT do that to a precision plate in an ISO9000 shop. But if he is determined to make his cheap grade B plate shiny, then why not? As I mentioned in my first post, I think that matte means freshly lapped and flat. Shiny probably happens over time as the plate wears. Get it re-lapped and it will be matte again - but more accurate. > Whilst I agree with you in principle, in practice I think it is > probably a non-issue. > > I worked for several years as a metallurgist, the difference between a > gloss and matt finish was the 1000 grit paper (and the 1um dimond for > the really shiny stuff) > > Your reference gauges etc will not drop into the finish. Flat is flat > in the macro sense. I think that the standard for iron plates is a few > dozen points per square inch. > > But, if you want shiny, then I really don't see car wax supporting the > weight of your height gauge. > > Matt will hold more blue. That could be a plus. > > I want this one. > http://www.ebay.com/itm/Gorton-Master-Surface-Plate-Historical-Vintage-Original-8000lbs-MSP-1928-/161246759544?pt=LH_DefaultDomain_0&hash=item258b0e4a78 > > Now that is a surface plate. And it is not shiny. Look at the plate They don't make 'em like they used to. Six years of aging before they started to scrape it. I wonder how long the scraping took? -- John Kasunich jmkasun...@fastmail.fm ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users