I used to have this problem on some of my early knives until an engineer from texas instruments let me know that there are several different grades of brass. This is going back 20 years so I may be off, but I believe he said that the brass you want to use is 360 brass. It doesn't tarnish as quickly. It will still tarnish. If you buy your brass from the knifemakers supply store's I believe that is the brass they sell. If you get brass at the hardware store it is a different grade. The 360 brass didn't tarnish as quick. Hope this helps.