Single Formvar vs. Poly

[fieldwrangler]

Thanks again; I plan to run this and other tests this weekend.

Bob Palmieri

[fieldwrangler]

First run results from this particular set of test conditions on 44ga. wire:

Old (1983) single Formvar (3 ft in small pot of saltwater): 8.0 nf and 30kacr @ 1k - 38nf and 38k acr at 120 hz

New (Remington) poly (same length in same pot): 5.2 nf and 35k acr @ 1K - 24 nf and 40k acr @120 hz

On Tuesday I plan to get some of the methylene chloride gel stripper, compare DCR's of equal lengths of wire and do my best to measure insulation and conductor thicknesses.

[Joe Gwinn]

First run results from this particular set of test conditions on 44ga. wire:

Old (1983) single Formvar (3 ft in small pot of saltwater): 8.0 nf and 30kacr @ 1k - 38nf and 38k acr at 120 hz.

New (Remington) poly (same length in same pot): 5.2 nf and 35k acr @ 1K - 24 nf and 40k acr @120 hz.

The difference of capacitance with frequency is an artifact - the Rac is too large to allow good measurements at 120 Hz.

For those that have the equipment, I'd try measurements at 10 KHz and 100 KHz.

[fieldwrangler]

So....

Soaked the wire samples (one Formvar & one poly) in methylene chloride gel for the 15 minutes suggested on the label, no effect on the insulation of either wire.

Left them to stew for 4 days, still no effect with a good clench on the wiping cloth.

Any other ideas on how to remove the insulation without nicking into the wire itself?

[Joe Gwinn]

I'm surprised that methylene chloride didn't work. Was the gel old and depleted? You should be able to smell the methylene chloride, and feel it if you have the gel on your skin.

There was a thread on insulating varnish, recommending MEK plus Acetone: http://music-electronics-forum.com/t18003/

Another alternative is paint strippers based on lye, used hot.

[fieldwrangler]

Thanks, Joe!

I'll be back at this next week.

Bob Palmieri