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Old 12th November 2010, 07:00 PM   #1
db! is offline db!  Canada
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Default Removing transformer varnish

Does anyone know of a solvent that can be used to remove/dissolve transformer varnish? I currently have a whole pile of salvaged EI laminations but I haven't found a way to clean them up. Some people recommend burning or baking the varnish off but I don't want to alter the metallic properties in any way.

Also, are these solvents safe for use on nylon bobbins and enamel wire?

Any advice would be appreciated!
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Old 12th November 2010, 07:35 PM   #2
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I've always had a problem with getting varnish off of wires and whatever too. Usually would up with a wire brush or chipping/scraping with a sharp edge - sandpaper - files etc. At work we used chemicals - but they were strong smelling and not environmentally friendly at all and consideration about getting rid of the used product made it's use a show stopper.

I decided to revisit the issue and came across this stuff - looks interesting and might be worth checking out.

Amazon.com: Safest Stripper Paint Varnish Remover Qt Paint & Varnish Remover: Sports & Outdoors

I have not used this stripper and thus cannot vouch for it. If you wind up giving it a try I would love to know if you like it or not.
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Last edited by c2cthomas; 12th November 2010 at 07:38 PM.
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Old 12th November 2010, 07:50 PM   #3
AJT is offline AJT  Philippines
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hi,

i dip those traffos inside a vat full of lacquer thinner completely submerged...... takes a week or so.....make sure you do this outdoors or in a well ventilated area...
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Old 12th November 2010, 08:01 PM   #4
db! is offline db!  Canada
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Thanks for input!

Tony - Will the lacquer thinner damage the bobbin and/or enamel on the wire?

Last edited by db!; 12th November 2010 at 08:07 PM.
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Old 12th November 2010, 08:38 PM   #5
Elvee is online now Elvee  Belgium
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Dichloromethane (DCM) is extremely efficient at the job, it will take tens of minutes or at the most hours instead of days to work, but it will remove the enamel of the wire, and damage most plastics.

It is highly volatile too, and you need to enclose the solvent and the "target" in an airtight container, otherwise it will evaporate before the job is complete.

As all chlorinated solvents, it is toxic, harmful, etc, etc.
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Old 12th November 2010, 08:41 PM   #6
AJT is offline AJT  Philippines
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Quote:
Originally Posted by db! View Post
Thanks for input!

Tony - Will the lacquer thinner damage the bobbin and/or enamel on the wire?

my experience is that no harm is done to plastics and wire enamels.....the thinner softens the varnish after a few days so that you can scrape them off...
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Old 17th November 2010, 03:09 AM   #7
ArtG is offline ArtG  United States
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I'd try whatever solvent you intend to use on a scrap piece of enameled wire before you start. I don't know what sort of enamel is used on wire, but lacquer thinner is very active and softens many plastics. Acrylic lacquer thinner is even more active than the "straight " variety that can be purchased at many hardware stores. If you intend to soak the transformer, I would start out with something relatively benign such as mineral spirits, often labeled as "paint thinner" before trying something more potent.
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Old 17th November 2010, 03:23 AM   #8
AJT is offline AJT  Philippines
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you may also try denatured alcohols......
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Old 17th November 2010, 04:22 AM   #9
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I was successful in the 80s at completely removing the varnish from a bunch of transformers by dunking them in a coffee can full of paint stripper for ~24 hours. The varnish bubbled up and rinsed right off. The coating on the magnet wire was not affected, but I didn't reuse it anyway.

These days it seems like they've removed a lot of the methylene chloride from paint stripper, as it doesn't work anywhere near as well as it did back then ( nasty stuff, I can see why they'd want to remove it). Xylene is one of the components of your standard transformer varnish, but that's not enough to get the job done, either, possibly due to the chemical changes that happen in the varnish when it's baked. Straight methylene chloride might be your best bet, though I don't know where you'd get it, and you'd want to strictly keep it outside of the house if you managed to get some. Don't get any on you - it burns like the hinges of hell, and it decomposes inside your body into nasty side products including carbon monoxide.
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Old 17th November 2010, 05:23 AM   #10
infinia is offline infinia  United States
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nasty job
Get one of the better paint removers, rubber gloves, stiff bristle scrub brushes, various putty knives, and some elbow grease. Next Q up how do I keep my laminations from rusting. LOL
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