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    What color to paint my Dynaco MK III transformers

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    GlacierJohn

    Posts : 38
    Join date : 2014-04-17

    What color to paint my Dynaco MK III transformers

    Post by GlacierJohn on Mon Aug 31, 2015 12:22 pm

    For the past few months I have been working with Holger (Tube Nirvana) on some custom panels that I will use in rebuilding my MK IIIs in the Tube Nirvana style. Holger gave me his blessing to talk about the project here. I am making my own custom wood chassis out of four quarter black walnut. Holger and I designed front, back, top and bottom aluminum panels drilled, cut, anodized and silkscreened in the Tube Nirvana style but modified for a roomier, balanced mirror image (right and left amp) look. The panels are done in that bronze look Holger uses. I already bought all new driver boards, I have the SDS power supply mod in my amps, new tubes, tube sockets, bias points, vu meters, all new wire, speaker post, inputs,everything.

    So now I am dismantling my old Mk IIIs, I will remove the transformer covers, fill in scratches, sand down super fine and paint. I like the blue Edcor transformers Holger uses on all his amps, I saw a thread where somebody used a US Navy grey that looked good and another where the guy painted them a kind of cream color. Of course most amps go basic black, any other ideas?

    Thanks

    John

    audiobill

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    Re: What color to paint my Dynaco MK III transformers

    Post by audiobill on Mon Aug 31, 2015 12:52 pm

    Bluemeanies did Ferrari Red, official paint.....

    sKiZo

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    Re: What color to paint my Dynaco MK III transformers

    Post by sKiZo on Mon Aug 31, 2015 1:03 pm

    I'm a fan of the basic black here. IMHO, iron's just too massive otherwise. Went with the Krylon matte black as per BobCo's. suggestion when I built my ST120.

    Here they are, baking out in the hot sun ...


    Dale Stevens

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    Re: What color to paint my Dynaco MK III transformers

    Post by Dale Stevens on Mon Aug 31, 2015 2:54 pm

    I use the Krylon Fusion saton black per Mr. Latino's suggest. I think the black finish will also dissipate heat best. Bob has a neat little tip in the assembly manual (for the ST120 anyway) to temp replace the xformer screws so as not to paint them although you may want to paint yours then replace w/shiny new ones. Dale

    10-E-C

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    Re: What color to paint my Dynaco MK III transformers

    Post by 10-E-C on Mon Aug 31, 2015 3:36 pm

    I used Harley Davidson Black wrinkle engine paint on mine.


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    vtshopdog

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    Re: What color to paint my Dynaco MK III transformers

    Post by vtshopdog on Mon Aug 31, 2015 8:07 pm

    I went through this in July painting mine.  I sampled several colors by masking the bells with wide tape, spraying them and dry fitting to chassis - This was helpful as I got to see the actual color on the amp.  After multiple trips to the Pep Boys engine paint aisle (they had 20-30 colors in stock) ended up using flat black on stacks and gloss metallic black on bells as my personal taste tends to the understated side of things.  

    I did look up some heat coefficients and technically flat black has the best radiant heat dissipation of any color with white and silver at bottom of list.  In general, thinner coats, dark and less glossy dissipate better.  Practically this is likely not really a huge issue as the differences are small and applicable to radiant heat transfer only, so if silver is what your really love, you can probably go for it but it will run warmer.

    How are you going to fill scratches?  I have no knowledge if Bondo type fillers are heat tolerant, but would be a bummer to find out after 5 hours run time that your filler expands at a different rate than the metal and causes paint to flake or crack.

    sKiZo

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    Re: What color to paint my Dynaco MK III transformers

    Post by sKiZo on Mon Aug 31, 2015 8:46 pm

    vtshopdog wrote:I did look up some heat coefficients and technically flat black has the best radiant heat dissipation of any color with white and silver at bottom of list.  In general, thinner coats, dark and less glossy dissipate better.  Practically this is likely not really a huge issue as the differences are small and applicable to radiant heat transfer only, so if silver is what your really love, you can probably go for it but it will run warmer.

    So, you're saying that chrome plating them isn't an option? I had some fun with the PT before deciding against it ...



    Although, technically, I suppose the metal tape wouldn't have been any thicker really than the paint ...



    Bob Latino
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    Re: What color to paint my Dynaco MK III transformers

    Post by Bob Latino on Mon Aug 31, 2015 9:16 pm

    Dale Stevens wrote:I use the Krylon Fusion saton black per Mr. Latino's suggest. I think the black finish will also dissipate heat best. Bob has a neat little tip in the assembly manual (for the ST120 anyway) to temp replace the xformer screws so as not to paint them although you may want to paint yours then replace w/shiny new ones.  Dale

    There are many black paints out there and you can use other colors if you want. The amp may run a couple of degrees warmer with some color other than black but it will be OK. Virtually any paint will stand up to the 140 degree Fahrenheit temperature that can be found on most power transformers after the amp has been on a few hours.

    Glossy paint is more likely to show drips, runs or minor spray errors. If you use a matte (flat) finish, some of these do not dry to a hard final surface and matte (flat) surfaces are harder to clean and may show wipe marks. I like semi-gloss or "satin" finishes and my favorite is the Krylon Fusion 2421 which is a satin black paint that Krylon says is "for plastic" but says also that it works well for metal items too. Krylon 2421 sets up to a hard semi gloss surface that looks nice.

    Both Krylon (#1618) and Rust Oleum also make "BBQ" paint or a barbecue black that is for spraying barbecue grilles. Both of these are real good high temperature paints but the surface IMHO does not look good on transformers. Both are more of a flat black. The Rust-Oleum version also does not spray a true black. The finished surface of the Rust-Oleum BBQ paint is more of a dark gray color.

    Bob

    wgallupe

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    Re: What color to paint my Dynaco MK III transformers

    Post by wgallupe on Tue Sep 01, 2015 10:52 am

    How about chrome plating...


    wgallupe

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    Re: What color to paint my Dynaco MK III transformers

    Post by wgallupe on Tue Sep 01, 2015 10:54 am

    Question: How does black paint dissipate heat any better than another paint color?

    Bob Latino
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    Re: What color to paint my Dynaco MK III transformers

    Post by Bob Latino on Tue Sep 01, 2015 11:59 am

    wgallupe wrote:Question: How does black paint dissipate heat any better than another paint color?  

    Read this forum post from June of 2011 ..

    Dissipation of heat from black objects

    Bob

    vtshopdog

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    Re: What color to paint my Dynaco MK III transformers

    Post by vtshopdog on Tue Sep 01, 2015 5:25 pm

    Key term here is "radiant". This is the heat you feel from glowing embers in a fire or an infrared food heating lamp. Black releases and absorbs these wavelengths better while light colors tend to reflect.

    For a transformer, likely the majority of cooling happens from simple conduction between the iron and contact with the surrounding air rather than via sending heat waves (radiant dissipation) into atmosphere. Color will make little or no difference in ability to conduct.

    wgallupe

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    Re: What color to paint my Dynaco MK III transformers

    Post by wgallupe on Tue Sep 01, 2015 5:37 pm

    That Wiki article was over my head Rolling Eyes However, I do remember all the old apartments in my area had heating system with (steam) radiators painted silver!

    Bob, I'm sure you've seen a few of these radiators in the '3 Deckers' around good old Worcester, MA Wink

    Bob Latino
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    Re: What color to paint my Dynaco MK III transformers

    Post by Bob Latino on Tue Sep 01, 2015 6:48 pm

    wgallupe wrote:That Wiki article was over my head Rolling Eyes However, I do remember all the old apartments in my area had heating system with (steam) radiators painted silver!

    Bob, I'm sure you've seen a few of these radiators in the '3 Deckers' around good old Worcester, MA Wink

    Yes - nearly all those old radiators were silver colored - but - I have also seen almost every automobile radiator painted black ..

    Bob

    j beede

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    Re: What color to paint my Dynaco MK III transformers

    Post by j beede on Wed Sep 02, 2015 1:37 am

    You have got to disassemble your transformers when you paint them. I find it is essential to put the thinnest possible coat of flat or satin black on the laminations to achieve a factory look.


    Jim McShane

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    Re: What color to paint my Dynaco MK III transformers

    Post by Jim McShane on Wed Sep 02, 2015 8:38 am

    vtshopdog wrote:Key term here is "radiant".  This is the heat you feel from glowing embers in a fire or an infrared food heating lamp. Black releases and absorbs these wavelengths better while light colors tend to reflect.

    For a transformer, likely the majority of cooling happens from simple conduction between the iron and contact with the surrounding air rather than via sending heat waves (radiant dissipation) into atmosphere.  Color will make little or no difference in ability to conduct.

    National Semiconductor does not agree on your color assertion. On page 6-1 of their outstanding 1980 Voltage Regulator Handbook there is a chart that lists the relative levels of emissivity, and black oil paint is #1. It has emissivity of nearly 20 x that of polished copper or aluminum.

    Do a Google search on 1980 National Semiconductor Power Supply Handbook and you can download and save the entire book. It is a GREAT resource.

    vtshopdog

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    Re: What color to paint my Dynaco MK III transformers

    Post by vtshopdog on Wed Sep 02, 2015 11:18 am

    Jim McShane wrote:
    vtshopdog wrote:Key term here is "radiant".  This is the heat you feel from glowing embers in a fire or an infrared food heating lamp. Black releases and absorbs these wavelengths better while light colors tend to reflect.

    For a transformer, likely the majority of cooling happens from simple conduction between the iron and contact with the surrounding air rather than via sending heat waves (radiant dissipation) into atmosphere.  Color will make little or no difference in ability to conduct.

    National Semiconductor does not agree on your color assertion. On page 6-1 of their outstanding 1980 Voltage Regulator Handbook there is a chart that lists the relative levels of emissivity, and black oil paint is #1. It has emissivity of nearly 20 x that of polished copper or aluminum.

    Do a Google search on 1980 National Semiconductor Power Supply Handbook and you can download and save the entire book. It is a GREAT resource.


    Hi Jim

    Actually we agree 100%.  The handbook chart refers to radiant emessivity coefficients which are in play for radiant heat transfer and black is better than anything else.  

    Perhaps I was unclear in attempting to point out that two independent heat transfer mechanisms are in play - radiation and conduction/convection.  Color matters for radiant transfer and likely is negligible for conduction/convection.  

    Rght above emessivity table in the handbook are heat transfer equations for cooling fins, and at first glance conduction/convection appears be dominant factor in that emessivity coeffecient is entered in the equation at 10(-10)(but I'm too lazy to do the math)

    For readers with eyes not glazed over, one interesting takeaway is that polished copper has a 10x lower radiant transfer than oxidized copper (or black painted), so in the case of a component operating at the margins of its range the color may impact operational life.  (weber copper cap discussion anyone??? )

    cheers, Tim

    sKiZo

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    Re: What color to paint my Dynaco MK III transformers

    Post by sKiZo on Wed Sep 02, 2015 1:36 pm

    Always felt the Dynaco design could benefit from a bit more air circulation. Especially seeing how tight all the heat producers are to each other.

    Just as important IMHO is ventilation courtesy of "chimney effect". A well ventilated chassis that can allow heat from the tubes and iron to pull cooler air up from underneath is desirable.



    Has anyone added vents to the stock chassis? You'd also need to vent the bottom plate to allow outside air to "refresh" as it's pulled up through the top plate by tube heating. The iron itself has a decent enough air gap to allow cool air to rise between the chassis and transformer bodies, but could also benefit from some judicial notching in all but the mounting points where you'd want to leave the stock metal for strength.

    corndog71

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    Re: What color to paint my Dynaco MK III transformers

    Post by corndog71 on Wed Sep 02, 2015 2:56 pm

    sKiZo wrote:Always felt the Dynaco design could benefit from a bit more air circulation. Especially seeing how tight all the heat producers are to each other.

    Yep.


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