Baking BH iron?

[jrebman]

This is a queestion for PJ mostly...

I want to try some wrinkle finish paint on some power and output transformers and the manufacturer of the paint I intend to use says that it's preferrable f you can bake the painted part in a 200 F oven for 30 to 60 minutes to both speed up the drying time(which I don't really care about) and to improve the wrinkle of the finish.

I'm assuming from the published working rating of the various power transformers, that they might be ok to bake, but I have no idea at all about the OPTs -- or should I just skip this altogether?  Certainly chassis plates and bellends are no problem, but if I want a uniform look, my guess is that all parts should be similarly treated.

Thanks,

Jim

 

[Yoder]

Hey Jim, I do most of my baking in the Colorado summer sun. Just don't leave your paint cans in the sun too long. I did once, and it blew the air nozzle out. Heating the can for an hour or so in the summer sun, does really help with the quality of the spray.

 

[Paul Joppa]

I have never asked about temperature capability of the audio iron parts. I have requested material with particular properties for the insulation between windings, so that may be different from what's in the power transformers - but I don't have material data specifications for the components. We don't physically build them ourselves and I am sure there are construction details I am unaware of.

Personally, I would not mess with the transformer itself. I do know that it is vacuum impregnated with some kind of material; I also know that the resistance between laminations is important (they are coated or otherwise treated before being stacked) and that their magnetic properties can be damaged by mechanical shock. I assume there are other risks I don't know about as well.

 

[jrebman]

Hey Ron, yes, I use that big solar oven too, but I don't think I want to wait for next summer to get these current projects done.

PJ, thanks -- good to know and I think I'll not attempt this, or maybe just use a lower temp heating lamp or something like that.

Thanks,

Jim

 

[Chris]

magnetic properties can be damaged by mechanical shock...... does that include getting bounced around by FedEx also.... are trannies usually tough enough to withstand shipping? maybe a dumb question, but my stuff has been shipped quite a few places , including 2 countries and back... thank you

 

[Grainger49]

Chris,

I know this is not the kind of shipping that you mean, yours is much longer, but for the last 5 moves I have not allowed the movers to touch my stereo.  I pack it, CD/LP and all, and I move it.  I rented a panel van last time for 4 days.

 

[Paul Joppa]

Shock is more impulsive than normal shipping - i.e., bubble wrap and even just corrugated cardboard are sufficient. High-nickel laminations are (I believe) the most sensitive, followed by 50% nickel, and then grain-oriented silicon steel. I don't know anything about shock sensitivity of amorphous core materials. With nickel laminations, the rule is, if you drop them on the concrete floor, you throw them out. Steel laminations are evened up with a soft brass hammer on a wooden bench, carefully - so they are relatively tolerant. Those are the two anecdotal bits of information I have.

Incidentally, Alnico is also prone to losing magnetization if dropped onto a hard surface....

 

[Chris]

Ok Thank You as always Paul...Nice to know my purposely over the top packaging habit is good enough.. and Yes Grainger, I am right there with you man, I do the same when I am in the U.S....Never had any damage whatsoever for THAT very reason.... My gear just means THAT much to me, As I am sure it is the same for the rest of this gang.....You learn those lessons REAL quick with stories like, I bought a MINT pair of Infinity RSIIIs a while back when living in London and told the Las Vegas guy (who was very professional in demeanor and packing) to send them to Washington State, He dropped off the 2 identical boxes at fedex Vegas, WELL, 1 speaker arrived while the OTHER apparently asked the driver that it wanted to take a very long scenic tour of the entire great State of California....AND the speaker must have misbehaved along the way something terrible, because when it finally arrived the box looked it was hung by its neck and dragged behind the truck until dead... However LUCKILY, the guys TRIPLE box packing philosophy, meant the speaker was still unscathed PHEW!!!! .... ok I better shut up cuz stories like this one are another thread altogether!!! Thank You again...

 

[ironbut]

Regarding the transformer baking,..
I baked some wrinkle finish a couple of years ago (it was a component cover) and the smell never left my electric oven!
Even after a couple of months and a few cycles of the "self cleaning", my home brewed pizzas still had the faint taste of whatever the heck the solvent/propellant that was in that stuff.
It was just lucky that the range was in pretty bad shape and I replaced it about a year ago.
Maybe a gas oven would be different but I'd never do that again!
I never did get the hang of using those wrinkle paints but I've heard that using a heat gun can work pretty well. You'd do well to practice with that paint before committing a transformer to it.

 

[Grainger49]

I was tempted to bake my Eros top plate, tube shields and transformer cover.  For some reason I thought the odor would never get out of the oven.  So they sat in the sun for 3 days instead.  It was warm outside and the metal was hot to the touch after an hour.

 

[jrebman]

Steve and Grainger,

Thanks for the warning, I think I'll leave the wrinkle paint until the summertime when we have plenty of sun and heat to do the job.  In the mean time, I think I'll stick with my powdercoating guy who does fantastic work (though obviously not transformers).

My oven is not one I wwant to or can replace, so I think keeping the solvent smell/taste out of it is best .

-- Jim

 

[ssssly]

I've "baked" components using a halogen shop light before. Don't think it will get it to 200 degrees within 30 min(guess it would depend on the wattage of the bulb, mine doesn't get that hot) Don't know how it will work for activating whatever causes the wrinkle in a wrinkle finish but it worked well for hardening enamel.

Would imagine any point heating source would have roughly the same effect.

As far as damage to the non magnetics in the transformer. Most soft adhesives that I have worked with start to break down around 300 degrees. Hard set adhesives, like what I would think would be used in a transformer generally 450 and above. Hard plastics 350-500 depending on the type.

If you set up a point heat source capable of a couple hundred degrees, I would think that it would be a decent mid point between optimal for the wrinkle finish and ensuring that the transformer wasn't overheated causing damage.