Baking Handset Cords Question

[Craig T]

MAJOR MAJOR WARNING!!!


DO NOT use twist ties that have stuff wrote on them. Like the ones with blue or black ink on a white tie, they will stain your cord. Use the ones that are one flat color. I very narrowly dodged a bullet with my best cord.

In fact don't even use color ones, use a regular white twist tie only. If you have a dark cord that is one thing, but watch it with the light colored ones.

[JorgeAmely]

Craig:

What if you use a nylon zip tie?

[Craig T]

I tell you what would have happened if I did that Jorge.

I would have saved 1.5 hours of fixing my mistake!  

Seems like a zip-tie would hold up to the heat. I was also gonna try some twine next time like for tying hay bales.

The sauna runs at about 210 degrees so I may try setting them up in there too. If you load the woodstove and walk off, it will max the thermometer out at 250 degrees. Good place for a cord to hang out for a while.

[McHeath]

In referring to a document that we were unaware of when our original posts were made, the temperature of the baking should be at 105 degrees

Yeah I read that article as well and wondered about that temperature.  And then he said only 20 minutes of time, well geesh 105 is nothing really, only slightly more than body temp. 

I think, and I may get blasted for this, but I think perhaps the author is remembering it wrong. 

I've gotten really good results with temps around 220 for cords.  The heat is going to change the covalent bonds between the molecules, if I recall science correctly, and I don't see how 105 degrees is enough to do that even when the materials were brand new.  The melting point of PVC is 80 celsius, or 176 F, which is the material I assume the coil cords were made from.  (may be wrong here) 

[Craig T]

Well 105 did not work as well for me on the hard wire cords, but it did improve the cord. I have a pair of the modular cords to do tomorrow. I will do one at 105 for 20/20 and one at 220 for 40/40 and see how they do. 

I had all great turnouts across the board. Every phone I fixed up in the Flea Market section now has a tight like new cord. Most notably the gray phone cord with the kink in it. Here are some before and after shots...

[Dennis Markham]

Much improved, Craig.

[JorgeAmely]

Craig:

Does the formula work well for black dull rubber fat curly cords? I have a 1955 phone with one of those.

[McHeath]

Yes it works well for those cords Jorge, the first cord I ever did with this method was one of those.  The only drawback was the smell while cooking it, hot rubber, not very pleasant and I was lucky the esposita was tolerant that night.

[JorgeAmely]

Mmnn, may have to postpone the renovation when wife and kids are out and I can open all windows. 

[Craig T]

That was one of the first cords I did Jorge and it was bad! Nearly stretched out straight. I baked it twice and it came out nice, but not quite like the others. It was so dry it will need a third session down the road. It was a bit tighter after it was done, it has settled to this point.

It was from 1946 out of a 302. Here is a pic of the cord before and after...

[Craig T]

Well here is my final report...

First off are two loose modular cords, I forgot to take a before pic of the Beige cord and it was already on the dowel. I ran each cord through one time.

The first cord was run at 105 20/20, shown afterward in the second picture. I used an NOS Beige Modular cord that had a couple kinks in it from how it was sitting in the package. The lower temp and shorter time did little for the cord and actually made my ends looser than they were.

The third pic shows after the 220 40/40. I re-did the Beige too and it came out excellent with the green one. The Beige cord was a little tighter, most likely because it was NOS to start with. The orange cord was too long for my dowel, I have another dowel coming in tonight for it.

[McHeath]

You are the first person I know of to do this procedure on a modular cord, and so it's good to know that the ends won't melt.  They WILL melt on an early Trimline cord with the giant modular type ends, I learned that lesson.

So I think that we've pretty well proven that baking a cord at 105 degrees F is not going to do anything really, you have to crank the temperature up to 220 ish degrees to get good results.

[Craig T]

Right on, I think that a person could even go 200 on the modular cords. They are somewhat thinner than the hardwire ones. Just an FYI, I used the freezer to cool this batch of cords too.

[Dennis Markham]

Your cords look very nice, Craig.  Was there improvement in the elasticity of the return to their resting shape after being stretched? 

[Craig T]

Yes there is some positive influence on the elasticity of the cord. However, as I read in one of the other cord baking threads, this works a lot better on phones for display rather than use.

My hypothesis at this point: A cord that had been baked and was previously stretched will get worse than a cord that has been baked and not been previously stretched out.

Perfect example is the formerly NOS Beige cord I have on my 514. It snaps right back into place even with a full stretch. Even after just one full stretch the Moss Green cord shows signs of stress during retraction.

Truth is I am still fine tuning the way I restore my cords. I have a couple other things I am trying right now to try and retain the elasticity of the cord.