On Wednesday, February 22, 2012 09:42:13 PM Peter Blodow did opine: > Gene, > blacking of brass is easy. Get yourself a small quantity (a piece of > fingernail size is enough) of potassium sulfide, K²S, from the pharmacy, > commonly called liver of sulphur and sold cheaply (in Germany) for > medical bath purposes, for instance, as skin cleaner for teenager (how > about that?). Dissolve a very small amount in a lot of water, so the > solution is only faintly brown, not more. Put in your degreased > workpiece and watch it under good lighting. It will turn brown and then > turn black, at which point you take it out quickly and rinse it under > running tap water with scrubbing (old toothbrush). If it seems to be > insufficiently black, repeat. > > The goal is to produce a very thin layer of copper sulfide on the > surface (dead black). Longer application will cause the layer to become > too thick and to peel off in tiny flakes or sheets. Depending on the > alloy, It may help to etch the brass at first with hot citric acid, > formic acid, acetic acid (concentrated vinegar), coffee percolator > cleaner (sulfonic acid) or some other organic acid to remove the zinc on > the surface, making the copper come out on the surface so the brass > appears reddish. In other words, my cleaning with Tarnex (toluol) is the reverse as it leaves the surface more zinc'y (white) than coppery (red). Thanks for that bit of enlightenment.
> No finishing afterwards as this will make the surface more dense and > reflective. That is how I've understood it. And other than blowing the lint or whatever out of the slots occasionally, there should be zero wearing of the finish in the slots. Thanks Peter. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> Health is merely the slowest possible rate at which one can die. ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
