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THE AM BULLETIN BOARD => Technical Forum => Topic started by: W1UJR on January 31, 2008, 05:13:22 PM



Title: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W1UJR on January 31, 2008, 05:13:22 PM
Hello all, I am in the midst of refinishing some transformer end bells.

I considered powder coating, but don't quite have enough to justify the cost, so aerosol paint is the way to go.

I'd like a durable finish, and was thinking of baking them in the oven.
Does this work with aerosol paints, or it is a waste of time.

Suggestions?

Tnx!



Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: w3jn on January 31, 2008, 07:35:31 PM
I bake stuff all the time... either in the main oven when the XYL is gone, or for small stuff, I bought a bigassed toaster oven at the local thrift store for a buck.  Definitely makes the finish more durable.


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W1UJR on January 31, 2008, 08:41:10 PM
Thanks guys!

I understand about the XYL John, I had some "feedback" when I ran a R390A RF deck through the dishwasher a few years back. Dishes had to be done by hand until the dishwasher was "safe" again.

I'll be baking tomorrow!

Man, some of that old paint is hard to strip off, has been sitting in a bucket of stripper for three days, tomorrrow is sandblast time!


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W2INR on January 31, 2008, 09:27:55 PM
Powder coat the bells yourself Bruce.
http://www.eastwoodco.com/jump.jsp?itemType=CATEGORY&itemID=458 (http://www.eastwoodco.com/jump.jsp?itemType=CATEGORY&itemID=458)


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W1UJR on January 31, 2008, 09:40:30 PM
You know Gary, I thought about buying one of those kits, it would probably pay off, as I just sent a big box of sheet metal out to CA to get stripped and wrinkle finished in powder coat.

Bu then I'd have to buy a media blaster to strip the finish, and a nice booth area to spray in and before you know it, I'd be working, not playing. :-)

If only I was retired, I just can't find the time.

I tell ya, the guy who redid my Utah TX chassis did a great job, stripping, matching and powder coating.
I need to post some photos of that project, its a fun little beast. Powder coating is the way to go, costly, but looks darn good!


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W2INR on January 31, 2008, 09:44:45 PM
Welp,

I have the cheap version listed on the site and it worked perfectly on the 300Z engine parts. I spent less than $200.00. I did a liquid stripping of the parts. I placed them in a bin and let things soak a few days. Cleaned them up and zapped them!

Just a thought...

Here is another sitehttp://www.caswellplating.com/powder/index.html (http://www.caswellplating.com/powder/index.html)


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W2INR on January 31, 2008, 10:08:36 PM
Check this out

http://forum.caswellplating.com/photopost/showphoto.php/photo/1175/cat/504 (http://forum.caswellplating.com/photopost/showphoto.php/photo/1175/cat/504)


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W1UJR on January 31, 2008, 10:18:43 PM
Here is a close approximation to the old wrinkled finish.

http://forum.caswellplating.com/photopost/showphoto.php/photo/272/size/big/cat/


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: Opcom on January 31, 2008, 11:30:11 PM
I did this cheap method on the whole chassis of an audio amp, turned out very pleasing.

http://www.montagar.com/~patj/aph_do.htm


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: WBear2GCR on February 01, 2008, 12:07:10 AM
Krylon ain't "paint" no more!!
It be a plastic thang that works like paint.
Dunno if it likes to be baked, but I rather doubt it.

The one that used to really like to be baked was Rustoleum. That baked up hard as a rock. An hour or so at 160 degrees was FB OM!
Not sure how much they have changed their formula.

They all probably have changed due to the VOC content rules over the last decade or so.

             _-_-bear


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: KB2WIG on February 01, 2008, 08:47:46 AM
Doesn't baking the paint melt that lil plastic nozzle??   klc


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W1UJR on February 01, 2008, 10:49:35 AM
Prompted by Bear's comments about "plastic paint", I checked with the folks at Krylon.
Guess I'll have to find another brand to bake... :-[

====
Hi Bruce,

Thank you for your inquiry with the Krylon website. We appreciate you
taking the time to contact us.

We don't offer any products in the Krylon line that are intended to be
baked. Most of the paints are not all that heat-resistant, and would fail
if put inside of an oven to be baked.

Thank you again for your inquiry. If you have any other questions, please
reply with complete message history and my name in the subject line, and I
will respond as quickly as possible.

Sincerely,
Eric
Krylon Product Support



Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: k4kyv on February 01, 2008, 11:38:33 AM
Over the years, I have painted many transformers with cast iron end bells, using Rustoleum satin (semi-gloss) black paint in a spray can.  I let it simply air dry, and it seem to become as hard and durable as the original paint when the transformer was new.  One of my painted transformers is in the storage area, and I often use it as a step stool to  reach  stuff on the shelf above it, and the paint hasn't worn off after several years and hundreds of footsteps.

The paint seems soft at first, but after it cures for several weeks it appears to be hard as a  rock.

My problem is finding the satin finish.  Most paint stores sell gloss and flat, but for some reason most of them seem reluctant to stock semi-gloss.

I usually don't use primer, but Rustoleum makes what they call "rusty metal primer".  It soaks into surface rust (loose scaly rust must be removed with a wire brush), kind of like a water soaks into a sponge, and hardens, so that the layer of rust impregnated with the cured paint is almost impossible to remove without heat or chemicals.


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: WA1GFZ on February 01, 2008, 12:04:46 PM
Every now and then someone would ride down the street at the beach QTH and nail the mail boxes with a baseball bat. My brother gave me a length of thick wall pipe with a 1/2 inch plate welded on it.
It was pretty rusty so I shot it with the rust stuff that left it a black color. then I shot it Rustoleum black.  That was 10 years ago and the last time I looked it still was sound. I put it in the ground with a hundred pounds of rock and a couple bags of concrete down about 3 feet. Just waiting for someone to give it their best shot. strap


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: WA1GFZ on February 01, 2008, 12:17:41 PM
up here in 1 land that method doesn't work well this time of the year


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: Todd, KA1KAQ on February 01, 2008, 12:26:23 PM
I agree, Don - I've had excellent results with Rustoleum vs Krylon. Even years back, Krylon never seemed as durable, folks complained about how easily it scratched or just plain wore off. One fellow repainted the knobs for his R-390A, wrapped them in Kleenex, and put them in his coat pocket to take to work for relining. When he got there, he was amazed to see the tissue had worn some of the paint off. 

Last thing I painted was a B&W cast aluminum dipole center. Same satin finish black (looks more authentic for many applications), baked the two halves at 150 degrees for 20 minutes or so, under the broiler element. Hard as nails. Stunk the house up, but was well worth it. I like John's idea of a big toaster oven from the SA or a yard sale. Things like car wheels require the big oven, though.

Works well for wrinkle finish too, thought it's been 15 yrs or more since I did that. Even application of the layers is the key there.



Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W1UJR on February 01, 2008, 12:36:57 PM
Every now and then someone would ride down the street at the beach QTH and nail the mail boxes with a baseball bat. My brother gave me a length of thick wall pipe with a 1/2 inch plate welded on it.
It was pretty rusty so I shot it with the rust stuff that left it a black color. then I shot it Rustoleum black.  That was 10 years ago and the last time I looked it still was sound. I put it in the ground with a hundred pounds of rock and a couple bags of concrete down about 3 feet. Just waiting for someone to give it their best shot. strap


Well, based on what you, Don and Todd have shared, sounds like Rustoleum is the way to go.
I wonder what they will say if I ask them about baking?

Gary's probably right, I should just break down and buy a powder coating set up, I just know that I'll use it once and then it will sit in the barn.
I've got this funny rule that if I don't use something 4 times per year, its cheaper to rent.
Think its along the same lines as the "F" rule..if it flies, floats, etc. its cheaper to rent.  ;)

I don't get the media blaster from my buddy until Monday, had a broken nozzle, so guess I've got the weekend to think of it.
I'm not sure what Stancor used on the end bells back in 193?, but it sure does not come off easily, back into the bucket of stripper it goes.


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: AB3L on February 01, 2008, 12:53:24 PM
If wrinkle is what you want call a Harley shop and ask about their black wrinkle. We did heads and cylinders with it in the past. Media blasted the items, baked them in the oven, take them out and apply the paint. They would wrinkle up real nice as the paint hit the metal. Let them dry in the air.
The paint was heat resistant= tough.

They might share their procedure if they are doing it themselves, like oven temp. I seem to remember 150/175...


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: W1UJR on February 01, 2008, 01:05:41 PM
This the beast its going into.

(http://www.w1ujr.net/Bruce's%20Bench/DSC01286_small.jpg)  (http://www.w1ujr.net/Bruce's%20Bench/DSC01288_small.jpg)

The chassis, with the xformer in question, before stripping and powder coating.
The chassis have now, been powder coated, just need to handle the rest.
(http://www.w1ujr.net/Bruce's%20Bench/DSC01300_small.jpg)  (http://www.w1ujr.net/Bruce's%20Bench/DSC01305_small.jpg)


And I know the big question is going to be "Why?".
The short answer, I like these little rigs, they are fun to use, moderately easy to fix, and most were cut up for parts long ago.


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: Steve - WB3HUZ on February 01, 2008, 03:32:28 PM
Heat lamps work too.

I've never felt any need to "bake" any of the standard "rattle can" spray paints in the oven. I have laid out parts in the sun after the paint was mostly cured and been mildly burned after trying to pick a piece up bare handed, forgetting that black metal parts get hot fast in direct sunshine.


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: N4JOY on February 01, 2008, 07:49:12 PM
I'm refinishing a NC-57 cabinet and am using Rustoleum spray paint.  I've learned that it is important to let the paint cure for a minimum of one week -- I wait two to three weeks to be safe.  Otherwise, the paint is very soft and will scratch or mark with the slightest touch.

Chris

   


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: WBear2GCR on February 01, 2008, 10:41:51 PM
Bake Rustoleum.

Makes it rock hard in an hour or so after it cools...

Usually < 200 deg. lower for lighter colors is a good idea. If I recall, about 140-160F is optimal for Rustoleon.

              _-_-WBear2GCR


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: WU2D on February 02, 2008, 08:59:43 AM
Frank is right - this is a poor time to paint in the basement!

Rustoleum has three super flat "specialty camo" paints on the shelves now with brown, green and grey. I am putting green this over the Rustoleum "rusty metal primer" which I let dry for two weeks.

The restoration is of a steel chassis which I got last month from a chap in the Northwest Territory for my Wireless set 19 MK II.

I like the color but I don't like the finish. What can I put over it to gloss it up?

Mike WU2D



Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: WBear2GCR on February 02, 2008, 09:46:46 AM
I'd use only a Rustoleum brand clear - they make satin and gloss.

Other brands might react with the residual VOCs in the paint and go crinkle.

              _-_-bear


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: WU2D on February 03, 2008, 09:02:21 PM
Bear

I will try the clear. Actually, now that I put the radio in the case it does not look too bad. I did not put much paint on yet. I am taking the radio to the Nashua Radio Club tomorrow. I am doing a program on 19 Set.

73's Mike


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: WBear2GCR on February 04, 2008, 11:23:43 AM
Yeah... I want a "FLICK" control on my rig too!  ;)

And a button for "NET" - so I'ze kin chzechgintoda net fast!  ;D

              _-_-bear


Title: Re: Refinishing Transformer Bells - Baking Aerosol Paint?
Post by: Tom W2ILA on February 04, 2008, 07:53:39 PM
Bruce,
Krylon and rustoleum work well for light refinishing that will not be exposed to the outside elements.  The finish will last well into the next lifetime unless you plan to entertain around the endbells or have trouble with the kids smashing their toys into them.

If the endbells are going to be installed outside on your tractor, I would recommend using an automotive finish.  You can get epoxy primers that are 2-stage and finish as satin black or satin gray.  These are incredably durable and the cure is not heat - its the magic of chemistry.
If you choose to topcoat you can use a single stage enamel or urethane.  Again, no heat required - its all better living through chemistry.
Last - if you are really really planning on driving that tractor with the end bells and transformer through the snow you may want to clear coat them.  The clear coat is lasting for years on newfangled cars and nobody waxes things anymore so imagine the life you will get out of it in a radio application.
Give these 30 days in the garage before bringing them inside because they continue to cure and smell.
another choice of paints is the eastwood catalog epoxy rattle cans.  They are expensive but I painted the SX62 and SX42 cabinets with them and they are quite durable.

Stay out of the hot sun
Tom
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands