Ultrasonic discolouration

[Graeme Fraser]

Any ideas?

I picked up a cheap second hand Apeks DS4 from Fleabay with the intention of servicing and using as a spare stage reg set. After disassembly, I noticed some internal flash rust, but nothing to severe. However, after I cleaned the metal parts in the ultrasonic bath with a 50° BIOX solution for 6 minutes, the previously 'rusty' parts came out with a strange 'brick dust' red staining, which remained after soaking in distilled water and drying. Although it looked like some kind of residue it wouldn't budge and didn't even leave any marks on the cleaning cloth.

I've since put everything back together and it performs absolutely fine; holding and maintaining a steady IP. Any thoughts and can /should I do anything about it?

Many thanks. G

 

[207diver]

That is a brass first stage so it won’t have “flash rust” you may be seeing bare brass where the chrome has worn off. If that is the case there is nothing to worry about. Pictures would help.

 

[ScubaJCBS]

Unrelated question what is a good ultrasonic cleaner?

 

[Graeme Fraser]

That is a brass first stage so it won’t have “flash rust” you may be seeing bare brass where the chrome has worn off. If that is the case there is nothing to worry about. Pictures would help.

That makes sense. Was just surprised at how how red it was, like red oxide primer.

Yes, unfortunately I put it back together before I thought about taking photos.

Thanks for your help. G

 

[Bob DBF]

Unrelated question what is a good ultrasonic cleaner?

Well not so much good, as serviceable for my reg repair and home shop use:

2.5 Liter Ultrasonic Cleaner

I've got 8 or 10 years on mine, and it worked fine on the parts from the old craftsman shop compressor I rebuilt recently. My regs are much cleaner than the compressor, so that was a real test.

 

[Jack Hammer]

Any ideas?

I picked up a cheap second hand Apeks DS4 from Fleabay with the intention of servicing and using as a spare stage reg set. After disassembly, I noticed some internal flash rust, but nothing to severe. However, after I cleaned the metal parts in the ultrasonic bath with a 50° BIOX solution for 6 minutes, the previously 'rusty' parts came out with a strange 'brick dust' red staining, which remained after soaking in distilled water and drying. Although it looked like some kind of residue it wouldn't budge and didn't even leave any marks on the cleaning cloth.

I've since put everything back together and it performs absolutely fine; holding and maintaining a steady IP. Any thoughts and can /should I do anything about it?

Many thanks. G

Sounds like you are seeing the brass. The chrome plating may have been worn, eaten, corroded, etc, away. As mentioned, pics would be helpful.

Unrelated question what is a good ultrasonic cleaner?

I've always liked Crest and Branson. For occasional use the Harbor freight model is pretty solid. That said, my Crest 500 will clean stuff in a few minutes that my HF 2.5L model took about an hour to do. The price differences between those two are dramatically different and, again, for occasional usage not really worth spending the extra dough to save a few minutes for most folks. In between are some really solid units for in the $150 range off eBay or Amazon that I think for the money are good enough for most people's needs.

 

[rsingler]

I originally bought the Chinese U/S. I mean, for $150 vs $600, why not?
Then my first one died at one year. No big deal. I bought a second. Then my second one burned out a circuit board at 6 months. The mfr sent me a new board, but by then I'd learned my lesson.
I spent the $600 on a Branson, and haven't looked back since.

As for that brick red color, the posters above have it exactly right. That's what old brass looks like, after removal of the verdigris. It doesn't wash off. But if you take some 6,000 grit Micromesh and rub it, you'll take off a few molecules and you'll see the bright fresh brass underneath. I'm not sure what oxide is responsible for that color, but it's a result of the underlying brass and whatever oxidation was in the green verdigris above it.

 

[The Ruttmeister]

Probably the copper, that goes brown to black and then eventually green.

 

[Graeme Fraser]

I originally bought the Chinese U/S. I mean, for $150 vs $600, why not?
Then my first one died at one year. No big deal. I bought a second. Then my second one burned out a circuit board at 6 months. The mfr sent me a new board, but by then I'd learned my lesson.
I spent the $600 on a Branson, and haven't looked back since.

As for that brick red color, the posters above have it exactly right. That's what old brass looks like, after removal of the verdigris. It doesn't wash off. But if you take some 6,000 grit Micromesh and rub it, you'll take off a few molecules and you'll see the bright fresh brass underneath. I'm not sure what oxide is responsible for that color, but it's a result of the underlying brass and whatever oxidation was in the green verdigris above it.

Hi @rsingler

Thanks for the info. Regarding the micro-mesh, is this the sort of thing? I wondered if these mesh tipped swabs would be handy for getting into orifices.

MICRO-MESH Sanding & Polishing Swabs - 3 Sizes Available | eBay

Unfortunately looks like I can only buy a set, but I'm sure I'll find a use for the other grades.

Many thanks in advance.

 

[rsingler]

Hi @rsingler

Thanks for the info. Regarding the micro-mesh, is this the sort of thing? I wondered if these mesh tipped swabs would be handy for getting into orifices.

MICRO-MESH Sanding & Polishing Swabs - 3 Sizes Available | eBay

Unfortunately looks like I can only buy a set, but I'm sure I'll find a use for the other grades.

Many thanks in advance.

Sorry for the delay, @Graeme Fraser !
I'm concerned that the swabs will prevent putting enough pressure on the areas you want to polish. Additionally, the fine grit gets clogged pretty quickly, so I'd be concerned (given the cost) that you'd be frustrated at what you spent vs. what you got. Here's what I use:

I'm sure you can find a cloth-backed Micromesh closer to home. Whatever you order, avoid the foam-backed pads. They do not conform well enough to the surfaces you want to polish.

Cheers!