Who needs digital

[ptross]

I'm no expert, but I believe the crumbling of the springs is the result of Hydrogen Embrittlement. it is not usually a factor in softer steel, but above Rockwell 32 or so it becomes an issue, so the arms of the calipers may not be affected but the hardened spring is. Electroplating or cleaning is a potential cause. Anyone interested should look it up, there's plenty written about it.
Peter

 

[ptross]

the second thing to avoid with evaporust is leaving any hardened parts half submerged. the area at the waterline will etch away (enough to spoil a precision surface). keep the item completely submerged.

 

[mmcmdl]

Dividers were pulled with no apparent damage to the springs . They did clean up nicely . Rinsed them in water , sprayed them down with regular WD-40 and wrapped them in a towel . I'll get some pics up when I get back home this afternoon .

 

[woodchucker]

I haven't pulled out my sample yet. later in the day to be 24 hours.
I have 2 left
one will wait for 2 days.

 

[ptross]

I'll be interested to hear how you test the springs for any change. If I have read the descriptions correctly there may not be any visible evidence when you first pull them out but the embrittlement can cause loss of flexibility, leading to premature cracking. You might have to give them a multiple cycle test of some sort.
Peter

 

[mmcmdl]

Back in one piece although I feel like a pin cushion ! I'll post a pic of the two that were soaked overnight . I'll then put a few more in for 24 hours and we'll see what happens if anything .

 

[graham-xrf]

@woodchucker
When I saw this video about first rusting a part (in a controlled way), then turning the rust into magnetite (bluing), I thought of you.
The magic stuff is hydrogen peroxide with salt added. It rusts in minutes!
Particularly - be warned about doing this to hardened parts. [4:20] The differential stress release from hydrogen embrittlement can have them go into a tragic self-destruct. Probably divider springs should not experience this!

 

[woodchucker]

good video... might have to try doing the black oxide thing.
as far as rust... that boat already left... But good to know.

 

[WobblyHand]

I popped off the springs and put some dividers into some Evaporust. We will see what happens in the morning. The springs come off pretty easily. Hope I can get them back on tomorrow!

 

[mmcmdl]

Pics of the 2 I did last night . I did put 2 more small pairs in at 4 this afternoon and will leave them in for 24 hours for a comp . Still some dark spots but not bad . The threads are now workable which they WERE NOT when put in . All in all , maybe it worked and progress was achieved . I'll hit them with a brass wire wheel and then some scotch brite for a final process . The other 2 will be removed at 4pm tomorrow .