Smokebox high temp paints

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Chris Hollands
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Smokebox high temp paints

Post by Chris Hollands » Thu Apr 15, 2021 9:35 pm

I have just started the process of painting the smokebox , it is getting sandblasted tomorrow ready for the main high temp paint .
I'm using Eastmans grey manifold paint rated at 1200F .
That's the easy part , getting high temp paints in other colours is an issue and the temp ratings on spray cans can be a little misleading .
Most paints that I have seen have a temp rating of around 250C/500-600F give or take .( yes they state higher temps until you read the fine print )
What I want to know is the auxiliary items attached to the smokebox - class light brackets etc will this paint handle the exterior temps as from what I see it is real border line .
I'm sure there is a lot of views on this matter and experience - let me know what has worked for you .

optigman
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Re: Smokebox high temp paints

Post by optigman » Thu Apr 15, 2021 11:39 pm

Stove Bright is an exceptional high heat paint. Use their high heat red primer.

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NP317
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Re: Smokebox high temp paints

Post by NP317 » Fri Apr 16, 2021 9:51 am

Previous discussions here have highlighed the use of "Dupli-Color" high temperature spray paints on smokeboxes, blackheads, and outside firebox sheets.
On my 1/8th scale locomotives this paint has worked perfectly over 15 years of steaming with no cracking, flaking, or need to repaint.
And their "Cast Iron" color accurately replicates the old steam cylinder oil + graphite coatings. I have applied lots of that during my full-sized steam locomotive days.
That color may or may not be appropriate for your locomotive. Other colors are available.
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hoppercar
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Re: Smokebox high temp paints

Post by hoppercar » Fri Apr 16, 2021 11:52 am

I use cast iron grey manifold paint from autozone.....they have hi temp manifold paint in several colors

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kenrinc
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Re: Smokebox high temp paints

Post by kenrinc » Fri Apr 16, 2021 3:39 pm

I went with this Eastwood product. It's since been re-labeled and I believe you can now buy it in cans which is really nice. I bought black and grey and originally, on my engine, I mixed a custom color but after I lived with it for a few months I ended up repainting with the stock grey color which identifies as "stainless steel". I wouldn't say that's a good description but it is what it is. I believe they have another that is described as "cast iron". It's been in use for about 7 years now. I've never had any issue with the accessories attached to the smokebox although I did use "high temp" paints on the headlight, numberplate and the markers. I believe it was just the standard duplicolor stuff.

Hey Chris! You saw it at Train Mountain :D

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Bill Shields
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Re: Smokebox high temp paints

Post by Bill Shields » Fri Apr 16, 2021 3:56 pm

I had good luck with my local power coating 'ceramic' finish that they use on motorcycle heads..many colors to choose from.

drawback is that it is like any other powder coat...once it chips....
Too many things going on to bother listing them.

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Marty_Knox
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Re: Smokebox high temp paints

Post by Marty_Knox » Sat Apr 17, 2021 1:15 pm

I use VHT header paint. Their SP998 Cast Iron is close enough to graphite for me. I spray it right on sandblasted steel. Once I fire the locomotive a couple of times I brush flake graphite on it.
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Berkman
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Re: Smokebox high temp paints

Post by Berkman » Sat Apr 17, 2021 2:01 pm

If you want a black smokebox, some have used stove paint as well.

SG3950
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Re: Smokebox high temp paints

Post by SG3950 » Sat Apr 17, 2021 3:53 pm

Chris,

I had my 0-6-0 test bed rigged up with many temperature sensors. One of the sensors was located directly in the center of smoke box about 2 or 3" forward of front tube sheet. Not in the exhaust steam flow. I ran that engine on both coal and propane. At 125# steam I rarely saw over 400 DegF internal temperature on that probe. The smoke box was .250" carbon steel. I never could measure surface temps of the smoke box when running. But I shot them with a laser a few times at stops. Never saw that over 300 DegF.

I am assuming you used Rogers smoke box casting. 1" thick cast iron will offer even more temperature gradient than the .250" CS on the 0-6-0. I do not believe any metal parts will be damaged by heat. The only thing I would be concerned with on a Challenger is the classification lamp and number board wiring.

I would still use a high heat paint. The above temps represent a properly functioning heat exchanger (boiler). Internal scale or soot in the tubes will reduce the amount of heat transferred to the water and increase the flue gas outlet temp proportionately.

I plan, meaning I have not yet done, to use a high heat paint that is several shades lighter than the color I want to end up at. Then rub the paint with graphite. I will try this on some scrap and heat up the backside to see what happens, but you get the idea. Actually if you try this let me know how it works!!

SG

k36no4862002
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Re: Smokebox high temp paints

Post by k36no4862002 » Sat Apr 17, 2021 4:16 pm

I have used stove enamel on my smokebox. In the UK I seem to be able to get it in loads of different colours.
So when I did the k36, graphite grey on the smokebox and black on the boiler under the lagging
The only annoying thing is that it needs baking to get it hard.
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Greg_Lewis
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Re: Smokebox high temp paints

Post by Greg_Lewis » Sat Apr 17, 2021 7:25 pm

SG3950 wrote:
Sat Apr 17, 2021 3:53 pm
Chris,

I had my 0-6-0 test bed rigged up with many temperature sensors. One of the sensors was located directly in the center of smoke box about 2 or 3" forward of front tube sheet. Not in the exhaust steam flow. I ran that engine on both coal and propane. At 125# steam I rarely saw over 400 DegF internal temperature on that probe. The smoke box was .250" carbon steel. I never could measure surface temps of the smoke box when running. But I shot them with a laser a few times at stops. Never saw that over 300 DegF.
....

Some years back I posted some research I did on smokebox temperatures. I checked 19 engines at a meet. My measurements were taken from the external surface of the smokebox. There were 24 readings as some engines were measured more than once. Dropping one extreme (611°F) the average of the remaining 23 readings was 323°F. The high was 430° and the low was 249°.

Here's a link to the data: viewtopic.php?f=8&t=16207&p=16207&hilit ... res#p16207
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 30 years of turning perfectly good metal into bits of useless scrap.

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ccvstmr
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Re: Smokebox high temp paints

Post by ccvstmr » Sun Apr 18, 2021 8:37 am

Greg_Lewis wrote:
Sat Apr 17, 2021 7:25 pm

Some years back I posted some research I did on smokebox temperatures. I checked 19 engines at a meet. My measurements were taken from the external surface of the smokebox. There were 24 readings as some engines were measured more than once. Dropping one extreme (611°F) the average of the remaining 23 readings was 323°F. The high was 430° and the low was 249°.

Here's a link to the data: viewtopic.php?f=8&t=16207&p=16207&hilit ... res#p16207
Greg...thanks for re-posting. Vaguely remember your "high level" study when posted years ago. With the proper tools, it's relatively easy to gather numbers for a simple comparison. Numbers talk...all else is hearsay and can only carry all the possibilities of a definite maybe.

For those of us with technical backgrounds, it's nice to see data provided to substantiate claims made. From your tabulation, MOST temps were in the 250 to 450 deg. F range...which should easily handle readily available high temp rated paints and finishes. Would surmise something was amiss with temp readings too high and a couple that seemed too low.

Believe your data "expedition" was back around the time when turbulators were first discussed on Chaski. Temperature drops experienced with and without turbulators were noted. Such that smokebox and stack temps went DOWN with the turbs in place compared to operation without the turbs. There was only one place the heat could go...into the water.

Above all else, when painting smokeboxes (or other metals for that matter), surface prep is important. Getting a smoke box off a loco frame is a major effort. Still, a good sand blast cleans the metal and gives paints a little more "bite" on the surface. Carl B.
Life is like a sewer...what you get out of it depends on what you put into it!
I don't walk on water...I just learned where some of the stepping stones are!
I love mankind...it's some of the people I can't stand!

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