Windings are magnet wire, and typically they're lacqured or varnished. Acetone will absolutely remove either of those and then you've killed the winding.

What are you trying to achieve?

SMALL amounts of soap and water and a toothbrush - afterwards, 2 or 3 hours in the sun

I would use a soft wire brush on the laminations.

personally, I wouldn't screw with it to much. You run the risk of really screwing things up. You could spray it off with water and leave it dry for days on end.

The well aged, glued, waxed, and thoroughly baked kraft paper around that thing is not going to take a wire brush.

Worse, wire brushing even the laminated iron core is going to get filings down around the windings, and then we'll find out (the hard way) if there's any gaps in the insulation. I wouldn't risk spraying water on it for the same reasons, even if you think it's dry afterwards. That is also going to rust the core.

I strongly advise doing no more than wiping it off very gently with a slightly damp (dry damp really) rag.

I'm facing the same thing
I'm going to give it a light brush and live with it not being clean

Let me clarify what I mean:

I would take a wire brush to the OUTSIDE, STEEL laminations ONLY

Then I would use a toothbrush and warm soapy water to clean the paper and windings

Then I would leave it to dry for a day or so in the sun

Then I would give it a coat of clear lacquer.

Alcohol of any kind is out.

It's very likely the varnish on the windings is lacquer, shellac, or classic enamel. Shellac is traditionally made by grinding up the secretions of lac insects, and...putting it into solution with alcohol. If you need to thin it, you use more alcohol. And as it dries, the alcohol evaporates and the finish hardens up

Lacquer may be made with shellac, or it can be entirely synthetic...but even the synthetic lacquers can be at least clouded or thinned, if not outright stripped with alcohol.

Even classic enamel (oleoresinous enamel) insulation on magnet wire is based around the use of some kind of solvent -- either alcohol or petroleum distillate. You won't know which until you use the wrong one on the transformer.

This is why I recommend you leave it alone -- older transformers are not solvent safe, period. Even many new ones will not be (although some of the new film type magnet wire insulation is pretty tough.)

Anyway, said my piece on this one...the choice is yours. But now you understand my reasoning.

Wipe the outside metal plates down with a damp cloth to remove accumulated grime, scuff sand with 180 or 220 grit and paint with flat black. I scrub the harnesses with a toothbrush turning the transformer on its side and work with the harness facing down so moisture doesn't get to the windings. New card stock can be laminated to the funky brown paper If need be but I usually leave it alone.

I take a dry paint brush and air compressor to it and knock off most of the crap that's on it. Then I go over the metal laminations with a brass bristled "detail" wire brush after first writing down the white stenciled Bally part numbers that are stenciled on it (E-xxx-xx). Then I spray paint the laminations with semi-flat Krylon spray paint and write the original Bally stenciled part number on the kraftboard with a Sharpie marker.

I never, ever get the transformer wet. You're just asking for trouble if you do get it wet in my opinion.

How about some pine-sol and a paint brush to get the dirt off

No, but I carefully hand draw the numbers back with a white Sharpie paint marker (get them at Hobby Lobby).