I have a CRT monitor with a noisy deflection yoke. If I slightly press on the windings they make a crunchy sound like the brushed on factory varnish has dried up and broken loose, allowing it to vibrate. I have some varnish, that safe to apply with a brush? Acetone breaks down lacquer I believe, I'm concerned the acetone may break down/damage the insulation on the coated magnet wire which is why I opted for varnish instead.
Why would lacquer contain acetone, to keep it thin? I did some research and varnish doesn't seem to be dissolved in acetone as a thinner. I assume brushing on varnish would be safe?
Then I read in the thread below that some varnishes contain toluene which is a solvent that softens some enamels.
https://www.practicalmachinist.com/foru ... ost-654665
Varnish Coating A Deflection Yoke
Re: Varnish Coating A Deflection Yoke
The key thing about what makes a Lacquer a Lacquer is that the paint can be reactivated with solvent or when coated with another layer of Lacquer it will melt into the previous layer.
The binder can be all kinds of material,Nitrocellulose, Shellac, Styrene, Acrylates and even some water based systems using Polyurethane resins can behave like a Lacquer if the right solvent is used. (Like high % IPA).
Solvents like Toluene, Acetone and even Water are just carriers for the coating. It's what allows paint to be applied to a surface and form the final film. The actual binder, additives and pigments/dyes dispersed/dissolved in the carrier are what is left once the carrier vaporizes into the air.
Lacquers cure by solvent evaporation(vaporization). When the solvent/carrier changes from liquid to vapor the binder forms into a solid sheet of plastic film. Once it's dry to the touch it's cured.
Oil based coatings (Often marked as "Varnish" which is really a misnomer. Any clear coat is a varnish) cure in a lot of different ways that take way longer than other paints because they aren't completely cured when they are dry to the touch. It takes a lot of time through oxidation for it to actually fully cure. Some don't actually fully cure at all. (Linseed for example)
Most water based paints are Emulsions (latex) which is why a water based varnish is almost always milk white. They go through a multiple stage cure like most Oil Varnish Clear Coats.(Coalescence rather than Oxidation)
Without knowing what kind of coating they used at the factory it's hard to say. I would test a tiny area with some Acetone if that's what you have. See if it causes the coating to pull up or wet. If it does, it was more than likely a solvent borne coating and you could coat it with another modern Lacquer. The problem is you won't find many Lacquer clear coats in most stores these days due to all the solvents.
And you are correct that Varnishes can contain Toluene, in fact most Oil based Varnishes you will find in store contain any combination of things like White Spirit, Petroleum Distillates,Naptha,sometimes solvents found in Lacquers like Xylene,Toluene, MEK or Acetone. All of which can eat into prior coatings or plastics like ABS,PS,etc.
What would be better to recoat it with is a clear coat that is more flexible and elastic that won't crack over time. I would recommend a water clear coat like this https://www.rustoleum.com/product-catal ... ater-based and you can brush it on without fear of it dissolving any old clear paint already on the Yoke. And the final coating will be more flexible than a Lacquer so it won't become brittle and crack like a lot of Lacquers.
The binder can be all kinds of material,Nitrocellulose, Shellac, Styrene, Acrylates and even some water based systems using Polyurethane resins can behave like a Lacquer if the right solvent is used. (Like high % IPA).
Solvents like Toluene, Acetone and even Water are just carriers for the coating. It's what allows paint to be applied to a surface and form the final film. The actual binder, additives and pigments/dyes dispersed/dissolved in the carrier are what is left once the carrier vaporizes into the air.
Lacquers cure by solvent evaporation(vaporization). When the solvent/carrier changes from liquid to vapor the binder forms into a solid sheet of plastic film. Once it's dry to the touch it's cured.
Oil based coatings (Often marked as "Varnish" which is really a misnomer. Any clear coat is a varnish) cure in a lot of different ways that take way longer than other paints because they aren't completely cured when they are dry to the touch. It takes a lot of time through oxidation for it to actually fully cure. Some don't actually fully cure at all. (Linseed for example)
Most water based paints are Emulsions (latex) which is why a water based varnish is almost always milk white. They go through a multiple stage cure like most Oil Varnish Clear Coats.(Coalescence rather than Oxidation)
Without knowing what kind of coating they used at the factory it's hard to say. I would test a tiny area with some Acetone if that's what you have. See if it causes the coating to pull up or wet. If it does, it was more than likely a solvent borne coating and you could coat it with another modern Lacquer. The problem is you won't find many Lacquer clear coats in most stores these days due to all the solvents.
And you are correct that Varnishes can contain Toluene, in fact most Oil based Varnishes you will find in store contain any combination of things like White Spirit, Petroleum Distillates,Naptha,sometimes solvents found in Lacquers like Xylene,Toluene, MEK or Acetone. All of which can eat into prior coatings or plastics like ABS,PS,etc.
What would be better to recoat it with is a clear coat that is more flexible and elastic that won't crack over time. I would recommend a water clear coat like this https://www.rustoleum.com/product-catal ... ater-based and you can brush it on without fear of it dissolving any old clear paint already on the Yoke. And the final coating will be more flexible than a Lacquer so it won't become brittle and crack like a lot of Lacquers.