brass turned pink/red after cleaning next to a bore brush

[Mas]

I cleaned my Norma 300 win mag brass in the Hornady sonic cleaner with Hornady brass cleaner solution. I also put my bronze bore brush in the sonic cleaner to clean it together with the brass. After 2 or 3 hours of cleaning (I did let the sonic cleaner rest every 30 minutes), a few brass that sat next next to the bronze brush turned pink/red. After drying the brass with the Hornady case dryer the pink color turned darker (like shown in the picture). The bronze brass also turned pink just like the brass did. THE STEEL CENTER PIECE OF THE BRONZR BRUSH, HOWEVER, TURNED COMPLETELY BLACK (IT USED TO BE SHINY STEEL)!

What exactly happened to the brass? Galvanic corrosion? Dezincification? Is it still safe to reload a case like that?

 

[lash]

I believe that you just copper plated (more like a copper wash) that brass and the brass parts of the brush. That should not have made your brass any weaker.

What solution did you use in your sonic cleaner?

 

[Mas]

I believe that you just copper plated (more like a copper wash) that brass and the brass parts of the brush. That should not have made your brass any weaker.

What solution did you use in your sonic cleaner?

Thanks for replying! I used Hornady Lock-n-Loader Sonic Gun Brass Cleaner solution. Could you please explain more about the copper wash part? I just noticed a very important detail, the center bar (presumably made of steel) of the bronze brush became completely black (it was shiny before). So maybe the galvanized iron from the steel bar was coated on the bronze?

 

[lash]

Okay, I am not a chemist or metallurgist, but what you have done is essentially a plating process due to the use of dissimilar metals and the acidic cleaning solution. It is related to both galvanic corrosion and plating. In your case, you had three/four different metals in the solution; brass, copper, steel and chromium (though the brass and copper are closely related). Here's a brief excerpt from an article on sonic cleaning:

Another point to consider is cleaning solution chemistry and its effect on the products you are cleaning. Solutions are generally classified as acidic, neutral or alkaline, and a wide variety of formulations are available. Selection is based on what you are cleaning and the type of contaminants being removed. Check our cleaning solution page for popular formulations or contact us to discuss your particular cleaning challenges.
Our final point for this post relates to the parts being cleaned. When practical, metal parts should be of the same composition. That is, don’t mix brass and bronze with steel or aluminum components. This is because different metals or alloys may result in discoloration on the surfaces where they come in contact with each other. In addition, metals and alloys respond better to cleaning solution chemistries formulated for them. Note that chromium-plated parts should not be sonically cleaned.

Found here:
https://iultrasonic.com/blog/ultrasonic-cleaning-tips-for-avoiding-parts-damage/

It is not a simple explanation, but it is also not uncommon when using acidic or base cleaning solutions and dissimilar metals over long/longish periods of high heat cleaning. I have seen aluminum parts that fell out of cleaning baskets in stainless steel tanks using a caustic cleaner and high heat. Over time they become anodized black. We've had them tested to confirm what was going on.

 

[lash]

Oh, and to answer your second question, a copper wash is essentially a very thin plating coat which provides the color but not any plating thickness to speak of.

 

[bjay]

Mine came out same color..after using lime n shine mix with purpleish dishwashing soap.i normally use blue color dishwashing soap lol

 

[Mas]

Okay, I am not a chemist or metallurgist, but what you have done is essentially a plating process due to the use of dissimilar metals and the acidic cleaning solution. It is related to both galvanic corrosion and plating. In your case, you had three/four different metals in the solution; brass, copper, steel and chromium (though the brass and copper are closely related). Here's a brief excerpt from an article on sonic cleaning:



Found here:
https://iultrasonic.com/blog/ultrasonic-cleaning-tips-for-avoiding-parts-damage/

It is not a simple explanation, but it is also not uncommon when using acidic or base cleaning solutions and dissimilar metals over long/longish periods of high heat cleaning. I have seen aluminum parts that fell out of cleaning baskets in stainless steel tanks using a caustic cleaner and high heat. Over time they become anodized black. We've had them tested to confirm what was going on.

Thank you very much for the explanation and reference!