alconox soap zinc reaction?

[coppercone2]

I noticed that when I restore stuff, things that are made of zinc, like zinc castings, if polished up, immediately react in a ultrasonic cleaner to get a light coat of tarnish in less then 10 seconds. Not a  big deal because its in spec, I just want to remove any metal residue from polishing before assembly.

I use it with alconox. Should I be using a different soap? Or is it just that this material generally oxidizes fast? I am talking about zinc cans. At least I think its zinc.

Citranox maybe?

could it be a battery reaction with the metal tank of the ultrasonic cleaner, so maybe I should use a barrier of some kind?

I notice the dish washer does this to zinc kitchen tools too (i.e. garlic press). But thats over the coarse of an hour, and it is also stainless steel. Not sure if its the soap or the tank or both or just water.

Alconox says:
Can be used on soft metals such as copper, aluminum, zinc and magnesium if rinsed promptly. Corrosion testing may be advisable.

But in my case, promtly does not work.. I watched it change surface finish like almost immediately. 4 seconds maybe.

The parts are well within specification still, because its mild, but if I could buy something better I would. 

[jmw]

I tried Alconox for PCB cleaning based on some recommendation here but I found it's reacting with solder and making it dull after a few minutes soak. It's an ionic solvent and seems to attack base metals quickly.

Maybe try something nonionic instead? I switched to Detergent 8 for PCB cleaning - harder to find and very expensive, but gentler to metals and I reuse working solutions to save money. This is a different application than yours, but it definitely seems Alconox is corroding for a lot of nonanodized surfaces.

[coppercone2]

Hmm I never noticed a problem with cleaning old PCB. But I also don't keep boards for too long, maybe 1-2 minutes. I only use it for post flux remover clean up, after I scrub it with a brush.

I find alconox does a beautiful job on stuff like dinky BNC connectors, and I ultra soniced a shit load of test equipment cards and never noticed a problem there. The solder joints come out looking alot better then when they went in.

But , I won't say I had primo stuff to clean to begin with, usually it looks like I start with a lost cause. I will take a look for detergent 8. What a generic name, like WD 40.

Actually scratch that, I only recently switched to alconox. I used to use simple green. I only did a few cards with it to remove conformal coating residue. I have no problems, but it was only 1 minute or so (expensive cards, got paranoid).

BUt for the electromechanical crap, I thought the alconox was doing a wonderful job, but that stuff was in a pitiful condition to begin with. I had alconox around maybe 1 month.

I did a BNC connector today in alconox that looked like crusty crap (6015 probe connector) and it came out bright and shiny. The aluminum bit was fine too. The only part that suffered was the zinc side plates.

So TLDR:
My experiance with alconox is that if you have stock nasty crimps, chassis elements, relays, etc... it does a wonderful job making them alot better. But, if you have a highly polished nonferrous metal object that is clean, it makes it worse. Unless its a BNC connector, it looks new. But that is gold and nickel or something.

And, if you strip conformal coating off a PCB with solvent, and there is like residue left behind under chips and stuff, the alconox ultrasonic dip makes it great, because my shit was still dirty after I used like 3/4 a can of alcohol spray on a small PCB hosing it down after removing the wrinkled stuff.