Brass tumbling, ultrasonic cleaning, yellowness, and idiocy

packrat · October 15, 2013

I recently tumbled about 100 cases, the first time I've used a tumbler. After I'd stopped grinning like an idiot at the shiny shiny, I put half of them in my ultrasonic cleaner with some James "Sea Clean", to remove the greasiness of the cleaning fluid (I'd used a couple of slugs of Brasso -- was that stupid?). The water was about 30 celsius to start and I set it to about 50. After 20 minutes the first batch came out shinier than ever and free from grease, probably the 'whitest' brass I've ever seen, so I was grinning even more like an idiot.

I put the second batch in the ultrasonic and left them the same time at the same temp, but when they came out they were noticeably yellower. They were still damn clean, and grease-free, but the yellow quickly wiped off my idiot grin and I went and kicked the dog.

I know they are fine, I'm not going to clean them again! but what did I do wrong? Should I have changed the water and added fresh Sea Clean? That's the only variable that changed. Oh except that the first batch went in and came up to temp from about 30C, whereas the second batch went straight in at 50C.. doesn't feel to me like that would be an issue. (Does the water even need to be hot?)

Yours

Confused of Cheam

MrCetrizine · October 15, 2013

Hot water seems to tarnish the cases. My ultrasonic has a heater and I found that cases would turn yellow in even slightly warmed water. Now I do mine in cold water with the heater turned off after tumbling and have never seen a change except lovely shiny primer pockets.