A problem in the kitchen(over cooked brass)

[Tim N]

Hi All,
This morning before going to the club I thought I would ultrasonic clean some cases then dry them in the oven 160 deg fan forced for 10 min
When I arrived to drop junior off at soccer I get a call asking if I want the oven turned off
Some have a purple tinge
Are they for the bin?

[Eric B]

From experience I'd say they will be fine. It may take two or three cleanings to get back to best colour, maybe a good tumble with a brass polish impregnated media. This can be worse if you haven't rinsed off citric acid from the cleaner well which makes me think it is a chemical reaction rather than a brass softening or tempering. I find the fan oven no hotter than 75 C plenty quick enough and at that does not cause discolouration.

[Tim L]

Been there, done that too

I stopped using the oven because it deposits oven fat on the brass (maybe I just don't clean the oven often enough).

I've taken to giving them a rinse in metho to displace the water then leave them to dry naturally, 10 mins and they're done.

[macguru]

just shoot it, it will be fine unless your oven is like an lpg blowtorch

[Tim N]

There has been one or two things come out of the oven looking like they've been hit with a blowtorch

[KHGS]

Hi All,
This morning before going to the club I thought I would ultrasonic clean some cases then dry them in the oven 160 deg fan forced for 10 min
When I arrived to drop junior off at soccer I get a call asking if I want the oven turned off
Some have a purple tinge
Are they for the bin?

Tim, how far down the cases does the colour change extend? where the colour has changed the brass temper will very likely be softer. Any colour change indicates a temper change in that area. The change may not be enough to be a concern, but who knows for sure without proper tests??? Brass is cheaper than eyes & actions!!!!
Keith H.

[BATattack]

annealing starts at 315 degrees Celsius so at 160 you SHOULD be OK.

[Tim N]

Thanks All,
I might ask wifey how to work the timer for the next lot

[Tim N]

Keith,
The cases were laid flat to dry and the discolouration is random.
I'm guessing the temp wouldn't have exceeded 160deg.
What risk is there if cases were fully annealed?

[Brad Y]

Wondering if its worth expanding and sizing the necks to try and work them a little and maybe a soft load before a full power load again? Just to try and work harden the brass in case it has weakened?

[KHGS]

Keith,
The cases were laid flat to dry and the discolouration is random.
I'm guessing the temp wouldn't have exceeded 160deg.
What risk is there if cases were fully annealed?

The length of exposure to 160deg is the problem. inspect closely, does the discolouration extend any more than one third of the case length from the front? If so the head of the case MAY be softer than the safe limit. I can't see the cases to make an any sort of assessment for you, they MAY be fine, it is up to you to decide that, I am only alerting you to a POSSIBLE danger.
Keith H.

[Chopper]

Is it worth a couple of bob , ? and the worry while you are pulling the trigger ? and the bloke next to you ? Sorry , Chop

[Barry Davies]

Get rid of them and dry the next lot with hot air.
Cheap experience.

[macguru]

I leave mine in for a couple of hours , i have done it for years, never had a case failure attributable to this , 150 degrees is not hot enough to anneal brass imho

[KHGS]

I leave mine in for a couple of hours , i have done it for years, never had a case failure attributable to this , 150 degrees is not hot enough to anneal brass imho

May explain premature primer pocket expansion, soaking the cases at such temps for extended periods will alter the temper. My advice for what it is worth, never use ovens for drying cases, hair dryers are MUCH safer!!
Keith H.