Quench oil contaminents ?

M

mtnsct

Joined
Jul 31, 2006
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Kevin brought up some interesting points about contamination in quench oil in the other thread so I thought I'd get another one going on this particular subject.

What are your options as the quenchant becomes contaminated? Obviously good technique should be practiced, but stuff happens. What about filtration? Maybe running your oil through a fine screen, paper filter etc.? Or are the contaminants produced that screw up the process become so small as to make filtering pointless? I've been using Tough Quench which is so dark that other than a film on the surface it's hard to tell what's going on inside it.
Besides visually seeing the crud in the oil what other indicators should you look for to avoid poor performance i.e. time to chuck the stuff?
Thanks, Rod
 
rats, small birds start to stink after they have been in there for a while, other than that i have no idea:D

I think as long as your getting a good and satisfactory quinch, a little extra in your quinch isnt a big deal. Water is definitely a no no, for safety reasons as much as anything else.

I had some water get into my peanut oil (when i used that) and upon quinch I was surprised with a splattering of oil/water... no fun.
 
It's dark in my shop, so I never really had a good look at the insides of my quench tank.

Then I moved the tank under a better light and noticed a long dead mouse in the tank.
I cleaned it out and cleaned my oil right away....

Still makes me smile thinking about all the knives I dunked into that oil and didnt see what else was in there.
 
If the contaminates are suspended in the oil, they might be hard to remove with out sending them through some kind of filter. I was thinking about one of those fryer oil filters that help re-claim fryer oil from turkey fryers etc. Not sure if there are other filters that would work, that was just the first thing that came to mind. One of those could probably filter the fines and leave the sludge on the bottom. -Matt-
 
The big enemies of quench oil are acid and alkali.
Keep water and other chemicals away and it will last a long time.Filter it as needed to remove the scale and crud.
The clay that is used to do differential hardening is not good to leave in there for long, either (They often contain sodium silicate and sodium hydroxide).
There are blacksmiths using their grandfather's oil.
Stacy
 
I'm also wondering about the number of quenching cycles a specific volume of quench oil can go through before replacement (assuming it is used properly).

Stacy, you mentioned some using grandads' quench oils but my question would be are these "antique" oils still doing their job in an optimal way as designed (by actual testing) or is it an assumption they still work "cuz I been doing it this way fur 45 yrs." Not looking for a joust, just trying to find some answers.
Thanks for the replies, Rod
 
I just built a quench tank, and the inside walls of it are rusted., after all it was scrap!
Should I be cleaning the rust out of this before I attempt to use it? Would the rust inside there act as a contaminant?
 
MrPurple said:
Should I be cleaning the rust out of this before I attempt to use it? Would the rust inside there act as a contaminant?
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Well, the rust above the oil might fall in a guess, I dont think thats really a problem, but it might look better if you cleaned it up a bit.

The rust underneath the oil will really only be a problem if you scratch the sides and rub it off right?

The oil should stop any more rusting after all.

If I had to do it over again myself, I would have painted the insides and outsides of my quench tank so it looked better and never had any chance of rusting...
 
The main point that I would put out there is that as knifemakers we can relax about the small stuff, flashing the oil and letting it burn until it is little more than tar is one thing (it is also poor quenching technique), but bits of stuff getting into the oil a little at a time is another. Much of what you hear about the life span of oil is from heavy industry, believe me that our dozen blades per month doesn’t even register compared to the massive quenching done in industry. So we can rest a little easier knowing we are not really pushing the oil all that hard.

Blue_Dragon said:
I would think a family of blacksmiths like that would know if their quench wasn't quenching anymore. :confused:
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I wouldn’t. Some of the biggest names among blade makers would have no clue how much their oil had went south, a lot of really funky things can happen in a heat treatment before that thar file begins to bitun on that thar edge. Not to mention that a huge majority would outright panic if you sneaked into their shop and switched their oil with a Parks or Houghton product, and the things suddenly weren’t soft enough for their other tests. And blacksmiths do quite a bit less heat treating than bladesmiths.

In the other thread I mentioned having Park #50 at one of my ABS intro classes, aside from ruining the oil, it was a disaster! With the level of hardness the blades were achieving the tempering schedules and equipment simply could not soften them to a level to reliably bend easily for the big test. I finally told students that there where two oils there- the thick black stuff in the pans with parts of Jimmy Hoffa in the bottom which was for test blades, and the stuff labeled #50 for the blades they were keeping.

mtnsct said:
…
Stacy, you mentioned some using grandads' quench oils but my question would be are these "antique" oils still doing their job in an optimal way as designed (by actual testing) or is it an assumption they still work "cuz I been doing it this way fur 45 yrs." Not looking for a joust, just trying to find some answers.
Thanks for the replies, Rod
Click to expand...

Mtnsct, I would strongly suspect your conclusion is correct.

MrPurple said:
I just built a quench tank, and the inside walls of it are rusted., after all it was scrap!
Should I be cleaning the rust out of this before I attempt to use it? Would the rust inside there act as a contaminant?
Click to expand...

If the rust is small enough to come off and discolor the oil then it is in suspension and you may have problems (I had this happen to some oil at the bottom of the 55 gallon drum that rusted inside, it wasn’t fun). But if the rust is large enough to just fall to the bottom then clean it out and carry on. The good news is that if you clean the rust all off it will be continually coated with oil after that :)
 
...And the LAST thing I want in my quench tank are parts of Jimmy Hoffa!!...:D

Thanks for the help, Kevin. Lotsa little details to be concerned about without becoming so anal that analysis parallesis sets in. I'm just amazed at how fast these oils dissapate the heat without blowing up into an inferno. Neat stuff.
 
I use vegetable oil for heat treating. I keep it covered to reduce contamination, which mostly works. The only contamination problem I've encountered was water from a leaking roof. I heated the oil, which entrained some of the water. The real problem was that, unseen to me, there was a fair amount of water still in the bottom of the tank. When I quenched a 1084 blade, the water prooved to sharp a quecnh and I heard that little "ting" that we all dread. The blade cracked.

Replacing the oil and fixing the roof solved the problem. I really think that with all the entrained water, even had the blade not cracked my hardening would have been uneven.

It's nice to have a dry smithy, especially in SW Oregon.

Gene
 
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