We have in our lab several pellet press dies which we use to produce powder discs for FTIR studies. A number of them are starting to show small dents on the "shiny" face which affects the likelihood of getting a good, viable disc. Is it worth trying to polish them smooth again with, say, a very mildly abrasive polish like gumption, brasso or even toothpaste?
Though it may sound strange, but I came across a colleague who recommended dilute HCl (say at 10% concentration) to polish such surfaces. I did not try it myself but my advice is to test this on a single press die. Then you decide to proceed with or discard such method.
Hello Harvey
Are the dies stainless steel or what? This depends.
Perhaps etching with different materials (I would avoid strong acids, and recommend mild acids like citric acid or acetic acid).
I also recommend cleaning the dies after each use, since remaining materials from discs may hurt the dies.
Thanks Hikmat. Yes, the dies are stainless steel (I probably should have mentioned that). Will give acetic acid a try...
Dr. Harvey
Since you specified that the dies are made of stainless steel, then avoid dilute HCl & use diluted phosphoric acid + boiling water ( after trying what Professor Hilal has recommended in case these acids did not polish the dies effeciently). I saw the application of H3PO4 in a website but I did not record it unfortunately.