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    Painting transformers on tube amps


    Bob Latino

    Posts : 2383
    Join date : 2008-11-26
    Location : Massachusetts

    Painting transformers on tube amps

    Post by Bob Latino on Tue Oct 20, 2015 4:07 pm

    Over the years I have used many different types of paints for painting transformers on tube amps. You don't really need any special "high temperature" paint on the transformers. The highest temperature that the paint will have to look at is about 140 - 145 degrees Fahrenheit. The only place you will find temperatures that high on a transformer set are on the plates of the power transformer. No spray paint that I have ever used has ever peeled off because of excessive heat.

    Color - I just paint them black but really any color will work fine. Black tends to give up heat a little faster than some other colors but the temperature difference is not that great.

    Type - I like a semi-gloss or a "satin" finish. You can use a flat paint but I don't think that the surface of a flat paint sets up as hard and is not as durable as a semi-gloss or satin finish. You can also use a glossy finish but beware of the fact that a glossy finish will tend to show any mistakes in your paint job (runs, drips etc.). A glossy finish may also appear too shiny and show reflections.

    Paint - My favorite transformer paints are the Krylon Fusion paints. Yes - These are specially formulated for painting plastic but they also work well on metal surfaces. The satin black is Krylon's #2421. It sets up with a hard and durable top surface that can be cleaned. See the link below for the different colors that are available. Any color beginning with a 23 is a gloss paint. Any color beginning with a 24 is a satin paint.

    Krylon Fusion paint

    Paints that I do not like are the high temperature "barbecue" paints. The one made by Krylon #1618 is not as durable as the Krylon Fusion #2421. Rustoleum also make a high temperature paint #249310. I don't like this one because the color (to my eyes) is a very dark gray rather than a true black.


    Peter W.

    Posts : 105
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Painting transformers on tube amps

    Post by Peter W. on Fri Aug 12, 2016 3:33 pm

    Any layer of paint is, in a small way, also a layer of insulation. So, the flatter the better for heat radiation. A rough surface radiates heat much better than a shiny surface. Agreed that properly operating transformers don't see much heat, but they will see less if painted flat.

    If one works outside in warm, sunny weather, and lets the transformer dry for several hours in the hot sun, a quality flat will be as durable as a quality gloss. Otherwise, an hour in a 150F oven after drying. But the key is prep. If I am going to paint a transformer, I will clean it first with an ammonia-based cleaner on a rag, then I use a soft *BRASS* brush on any rust, then clean with acetone on a rag (not poured onto the transformer itself) to remove any loose paint, grease or other residue, as well as break the surface of the existing paint. Then a green scrubbie dry on the rest of the transformer to rough the broken surface. THEN paint it, spray or brush. I use a flat paint, they look almost new. If I could somehow fake the numbers easily, they would look new....

    Krylon is good stuff. I often use the term "accept no substitutes" together with Krylon products.


    Posts : 63
    Join date : 2016-08-07

    Re: Painting transformers on tube amps

    Post by LeGrace on Sat Aug 13, 2016 6:47 am

    I learned the barbecue paint lesson the hard way. Not durable as Bob says. I repeatedly found myself touching up chips and other marks that would seemingly appear out of nowhere whenever I set them down. Finally I resorted to applying a clear topcoat to protect the paint. Look good now, but taking a lot of effort to get there.

    My first amp I'm calling my "rookie mistakes" amp. I'll be doing a few things differently when I get to the second one!

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