Cryogenic treatment of guitars warning

[big_teee]

I'm pretty good at cutting coils off with an Exacto knife.
So if you Cryo a whole pickup does it need to be wax potted?
Wouldn't it hold up better during treatment if it is already in solid wax?

[Chuck H]

Chuck, this information isn't that hard to find unless you really don't want to find it, which seems to be the case here.

My search wasn't done with the intent of NOT finding something. I simply didn't. Other than my position what is it that makes you think I would intentionally search fruitlessly? I'll accept failure but not an accusation on my character.

2.4 Effects of Cold/Cryogenic Treatments on Copper
and Copper Alloys
The effects of cryogenics on copper and its alloys have
been investigated less in comparison to steel materials.
Effect of cryogenic treatment including tempering (2 hours
at 589 K) on thermal conductivity of copper-based (Cr-Cu
alloy 182) resistance welding electrodes was investigated
in a study [21]. It was found that the cryogenic treatment
increased the thermal conductivity from 3% to 4% without
affecting the hardness due to the fact that the equilibrium
amount of chromium in solution in copper was lower at
lower temperatures. Another study [22] on the effect of
cryogenic treatment on another copper alloy (GRCop-84)
showed that cryogenic treatment followed by tempering
reduced the hardness by 6% and it was also resulted
reduction in electrical resistivity by 5-6% and
correspondingly (according to the Wiedemann-Franz-
Lorenz Law) higher thermal conductivity. However,
cryogenic treatment without tempering was resulted larger
electrical resistivity values. So, it can be concluded that a
proper cryogenic treatment process is beneficial to copper
alloys.

So it looks to me like you can expect an increase in resistance unless the copper is tempered afterward. I might be concerned with how that could affect the magnetism of an assembled pickup.

Chuck, you're welcome to put your money where your mouth is, too, rather than project highly selected, ten year old information onto this time, place, and inquiry.

Another character bash? What's wrong with old information? Before new information is offered it's all we have! We've known the world is round for centuries but I suppose I shouldn't say as much IN CASE that information has changed? That's a pretty weak position. And I'm not funding the project because it's not important to me.

In case your eyes were closed I backed you on cryogenics for stress relief.

If you want to bash me, bash me for being an A-hole. I can take it. I even deserve it sometimes.

Go smoke in bed

[Mike Sulzer]

So it looks to me like you can expect an increase in resistance unless the copper is tempered afterward. I might be concerned with how that could affect the magnetism of an assembled pickup.

I believe that tempering copper involves working the material; that is tough to do after the pickup has been wound. I see no reason for increasing the resistance, and if you want to there are many ways. I think a better approach here would be to cryo the pickup parts, rather than the whole thing, and keep identical untreated parts, checking for differences by measurement and sound of the final product. (If you cannot compare pickups using treated parts to untreated ones, you can neither make a significant repeatable difference in the manufactured product, nor understand what you have done.


I do not see why increasing the resistance wpuld affect the magnetism.

[Chuck H]

The article stated that a cryo treat on it's own actually created an increase in resistance. That's why I mentioned it. But it occurs to me that the metals tested were copper alloys. The addition of trace elements to render the copper harder for structural purposes and/or more wear and oxide resistant for contacts. This MAY be key to the study. Perhaps these alloys LOSE conductivity over pure copper and that is somewhat restored by the temperature treatments proposed. There may be no advantage to cryo treatment for magnet wire. More research is needed. I'll poke around. If I don't find anything I'll let you know since you're apparently better at finding such info than I am

[Chuck H]

Hey! I actually found something!

http://info.ornl.gov/sites/publicati...s/Pub35345.pdf

It looks to me like the stresses of the alloying or working causes resistance to creep up and is somewhat undone by the cryo treatment proposed (followed by tempering). Unfortunately it looks like such problems don't exist for the more pure form of copper used to make magnet wire. I'll predict no permanent change in resistance by cryo treating pickup coils. But there's still the hope that some magnetic properties may be improved in alnico or mild steel rods used for pole pieces. My suggestion for such a test would be to heat treat the metal/s and follow with a cryo treatment and then a temper. Though I can't comment on ideal temperatures for the metals in question this process has proven most effective for creating a uniform grain structure and the most complete desirable conversions in the steels I'm more familiar with. This complicates the test of course. But if it's all about that last 2-4% as has been mentioned... As it often is.

[Rick Turner]

What I want to know is "if" something happens, and if it does, "what" are the apparent effects, and "what" are the implications for pickup makers. If resistance of copper wire goes up, fine. That may not be a beneficial effect, but it's an effect, and we'll learn something. If it goes down, fine. That is probably a beneficial effect, but we'll just have to see.

I'm not particularly interested in projecting results on knife blades to results with pickups as a theoretical and untested issue anymore than I want to taste an apple when I bite into an orange. My snarky responses have been in reaction to what I see as a closed minded attitude to experimentation and a quest for greater understanding.

We do seem to be reaching some sort of reason here. We now know that there are magnetic property differences between austenitic and martensitic steel...and that cryo treating helps nudge austenite into martensite. So we have at least a tested basis for thinking that the permeability of steel in pickups might just be improved with cryo treatment. We have seen some inconclusive data re. the resistance of copper alloys changing with cryo treatment...and remember, all we're exploring here is quantitative change...we're not ascribing good/bad qualities to the changes at this point.

We don't know diddly about possible changes to Alnico, to say nothing of ferrite, sumarium cobalt, or neo magnets, but I'd suggest that before we come to unsubtantiated conclusions based on evidence that is far afield, that we might just want to test this stuff to the best of our abilities. I can't find anything on cryo treating of these materials on-line.

It is possible that we are in the forefront of some of this kind of research...it's possible that out there beyond our little specialty, nobody has tried testing the DCR of the kinds of lengths of tiny copper wire that we use. Maybe nobody has tested the steels we use for magnetic changes beyond the cruder effects. I do know that if you talk to the guys at the magnet companies, they think we're out of our skulls for thinking we hear differences when we put different magnets into pickups. Etc., etc.

[salvarsan]

Testing Pickups

I think we should go with what we know.
This forum has documented tests for DC resistance, inductance, and magnet strength, so they would have the most meaning to members.

While exact BH and hysteresis curves would be a little more unambiguous, they cost too damn much.

[Rick Turner]

Agreed.

Do all tests at 68 degrees F.

Do the Exotech or other LCR meter readings drift with battery strength?

[salvarsan]

Agreed.

Do all tests at 68 degrees F.

Do the Exotech or other LCR meter readings drift with battery strength?

Clarification: record the ambient temperature when you measure DC resistance. That way, the 68F value can be calculated for meaningful comparisons. A 4.6F temperature change causes a 1% change in copper DC resistance.

Hyperphysics has a web app that works in Celsius degrees.

REA has a handy chart for copper resistance correction factors.

I imagine the ExTech is usually within its claimed 0.2% accuracy.
That should be fine since we are looking for 1-5% changes.

[ScottA]

If there are differences in the tonal response of AlNiCo alloys with cryogenic treatment, I'm pretty sure I can quantify it.

I have AlNiCo 5 and 2 samples that I could throw into a cryo run. let me know who's going to do it and I'll throw some in. I'll measure them before and after.

Some other general comments:

Absolutely there are quantifiable and significant differences between the AlNiCo alloys. I don't think this precludes that cryo treatment may possibly impart measureable differences to a single AlNiCo alloy. There seems to be pretty good evidence that even slight formulation changes around a base AlNiCo grade can affect tonal response, at least there are more than a couple of makers touting custom AlNiCo formulations based on analysis of historical samples. In my work, I've seen quantifiable differences in AlNiCo grades from different sources.

Microstructural changes, such as those brought about through heat treatment, can absolutely affect electrical properties. The grain structure of an alloy can have a significant impact on how it acts electromagnetically. Look up electromigration in copper, or grain oriented steels. I've got materials that act differently depending on how the rolling direction is oriented with respect to the magnetic field.

[Rick Turner]

Well, Mr Tee and Scott have offered to put product on the line. Do I hear anything from a humbucker maker or should I just get one from Seymour? And Salversan, would you like to do the testing on the Strat and humbucker pickups?

There's only one way we're going to learn anything other than doing this. It's easy to dismiss cryo as being snake oil. But what if it isn't? And humbuckers, at least, do have important steel components.

[ScottA]

Well, Mr Tee and Scott have offered to put product on the line. Do I hear anything from a humbucker maker or should I just get one from Seymour? And Salversan, would you like to do the testing on the Strat and humbucker pickups?

There's only one way we're going to learn anything other than doing this. It's easy to dismiss cryo as being snake oil. But what if it isn't? And humbuckers, at least, do have important steel components.

My measurements won't be full pickups, but a test set-up designed to get at material properties more directly. I've found that mutual coupling between pole pieces in a full pickup mucks up the response in the measurement.

I was thinking of just doing the AlNiCo pole pieces themselves first. Maybe do a coil/pole piece pair, or even just a coil by itself as a follow-up or in parallel.

I could throw a low carbon steel pole piece in as well.

[Rick Turner]

Scott, I'm fine with however you want to do it. Would you like to test a coil as well?

I'm told that the cryo treatment freezes the hum right out of the picture...:-)

[ScottA]

Would you like to test a coil as well?

Might as well.

Hummmmmmmmmmm.

[Chuck H]

Well, it's been said that speculation isn't the goal. But it's hard not to. WRT copper and copper alloys the evidence is there and I think the outcome is predictable, BUT... As mentioned, it's a very long run of very fine wire. I'd bet no one has tested such a device. As to the magnetic properties of the magnet metals, again I can't help but speculate. I'm thinking of transformer laminates now. Grain oriented steel. It's function is to charge effectively but also discharge effectively and recharge in opposing polarity. Iron is a pretty course material, but if any grain orientation occurs, or even more and finer grain development then who knows!?! There may be notable changes in cryo treated magnets then. It'll be interesting to learn.

I want to apologize for being an A-hole about it. I do believe that the changes will be too small and ambiguous to matter ("better" vs. "worse" being entirely subjective as well) and so I felt justified (wrongly) in saying "don't bother". But I was wrong. Wrong to tell others to subscribe to my opinion. Even more wrong in that there are things I'm nit picky about that others have told me don't matter. So there you go.

EDIT: Thinking about it, I'm still inclined to defend my position. In the OP a guy had taken an entire guitar (finished wood, plastics screwed to it, glue joints, etc.) and submitted it to obscene low temperatures. Given the voodoo surrounding so much cryogenic service it seemed appropriate to say "stop freezing your stuff". But if the end result is delving into areas previously unexplored (and as long as it's someone else's guitar ) power to the forum.

Peace.