Sulphur Oil on Electronic Parts

Hi Charlie, I'm pretty sure it's related to sulfur's chemical attack of copper, check out:

[note, some non-English language, just go past it]

GPN

Charlie:

I found these, they aren't specifically about sulfur containing cutting oils, but they do indicate that sulfur is corrosive to copper and it's alloys:

================================================================

Copper and its alloys are susceptible to rapid attack in oxidizing acids, oxidizing heavy-metal salts, and sulfur and ammonia and their compounds. ================================================================

================================================================

[0002]Insulating oils are used in power transformers, distribution transformers and reactors. These oils often contain traces of reactive sulfur compounds, especially thiols (a.k.a. mercaptans). The reactive sulfur compounds may react with copper, forming copper mercaptides. The copper mercaptides can decompose further, leading to the formation of copper(I)sulfide, Cu2S. The net reactions could be as shown below:

Cu2O+2RSH=>2 CuSR+H2O

2CuSR=>Cu2S+RSR

where --SH is a thiol group (or mercaptan), --R is an alkyl group.

[0003]Other sulfurorganics, especially sulfides, can also be active, either by direct reaction with copper or via conversion to thiols. [0004]Cu2S is insoluble in oil and may form deposits, especially on surfaces of cellulose material. Once deposition of Cu2S has started the process is believed to be self-catalytic. The surface selectively adsorbs the reactants and intermediates, and also catalyzes the decomposition of intermediates to Cu2S. ================================================================

================================================================

The problem occurs because the corrosive sulfur reacts with copper conductors and silver contacts to form metal sulfides that contaminate the insulating paper. ================================================================

I'd call you local coolant distributor, if you've been using water soluble cutting oil, you might be disappointed at the cooling ability of straight oil.

Thanks, guys. A little research led me to copper reacting with sulphur, but I had to make sure there wasn't something more sinister going on. For what I'm doing it won't be an issue, but I always like to make sure before I do something like buy cutting oil I shouldn't be using. I was given a free sample of some kind of tapping and cutting fluid to try as a replacement for oil, but it smells like moldy clothes when it gets hot. Yuk.

Later,

Charlie

If you happen down my way again I can give you a couple of 5 gal cans full or more. I collect that stuff it's like gold .

Dang, Dave, At the rate I would use it a 5 gallon can would last 300 years. Next time I make it south again I will stop in to say hi, though.

Later,

Charlie