I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an option (because part slides in C.I. supports and bushes aren't feasible). Many
years ago I had success with oil blackening of small parts but I'm
dubious about being able to get the whole rod up to an adequate
temperature before it takes the plunge (I can make a suitable bath using
a bit of C.I. guttering that's in the useful bits pile).
Has anyone got any words of advice, or a room temperature process to
suggest?

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Graeme wrote:

In message <mbik75Fo5bmU1@mid.individual.net>, No mail
<nomail@aolbin.com> writes

I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an
option (because part slides in C.I. supports and bushes aren't
feasible). Many years ago I had success with oil blackening of small
parts but I'm dubious about being able to get the whole rod up to an
adequate temperature before it takes the plunge (I can make a suitable
bath using a bit of C.I. guttering that's in the useful bits pile).

I have had success with both gun blue and Zebo, but am not sure either
would stand up to sliding use.

Thanks, I hadn't heard of Zebo.
The sliding is not very frequent - it's the pull rod on an old "Butler's Bell"** - so once per week, possibly.

** like this: https://doorbellworld.com/products/polished-chrome-traditional-butlers-bell-kit-with-black-iron-pull

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In message <mbik75Fo5bmU1@mid.individual.net>, No mail
<nomail@aolbin.com> writes

I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an
option (because part slides in C.I. supports and bushes aren't
feasible). Many years ago I had success with oil blackening of small
parts but I'm dubious about being able to get the whole rod up to an
adequate temperature before it takes the plunge (I can make a suitable
bath using a bit of C.I. guttering that's in the useful bits pile).

I have had success with both gun blue and Zebo, but am not sure either
would stand up to sliding use.

--
Graeme

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On 19/06/2025 15:12, No mail wrote:

I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an option (because part slides in C.I. supports and bushes aren't feasible). Many
years ago I had success with oil blackening of small parts but I'm
dubious about being able to get the whole rod up to an adequate
temperature before it takes the plunge (I can make a suitable bath using
a bit of C.I. guttering that's in the useful bits pile).
Has anyone got any words of advice, or a room temperature process to
suggest?

Blackgates, the model engineering supplier, sell a kit called
"MetalBlak" specifically for blacking steel. It is a room temperature
process.

Page 134 in their catalogue

http://www.blackgates.co.uk/CAT_Blackgates_Catalogue_2024.pdf

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David wrote:

On 19/06/2025 15:12, No mail wrote:

I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an
option (because part slides in C.I. supports and bushes aren't
feasible). Many years ago I had success with oil blackening of small
parts but I'm dubious about being able to get the whole rod up to an
adequate temperature before it takes the plunge (I can make a suitable
bath using a bit of C.I. guttering that's in the useful bits pile).
Has anyone got any words of advice, or a room temperature process to
suggest?

Blackgates, the model engineering supplier, sell a kit called
"MetalBlak" specifically for blacking steel. It is a room temperature process.

Page 134 in their catalogue

http://www.blackgates.co.uk/CAT_Blackgates_Catalogue_2024.pdf

Thanks! What a wonderful catalogue.
I now see that Chronos also sell a cold process kit.
From doing a bit more research it seems that heating and quenching in
oil gives a more robust finish, but these room temp systems are
definitely the way to go for this rod. I can easily make a suitable
trough by cutting a piece of waste pipe in half and closing-off the ends.

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On Thu, 19 Jun 2025 15:12:52 +0100, No mail <nomail@aolbin.com> wrote:

I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an option >(because part slides in C.I. supports and bushes aren't feasible). Many
years ago I had success with oil blackening of small parts but I'm
dubious about being able to get the whole rod up to an adequate
temperature before it takes the plunge (I can make a suitable bath using
a bit of C.I. guttering that's in the useful bits pile).
Has anyone got any words of advice, or a room temperature process to
suggest?

You may be able to get away with oiling the steel and then heating it with a blowtorch, bit by bit. Maybe wipe extra oil on with a thick wadded rag.

Or look at tannic acid: tannic acid in IPA, wipe on, wait overnight. Deep black.

Some rust converters are tannic-acid-based.

Thomas Prufer

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On 20/06/2025 09:56, Thomas Prufer wrote:

On Thu, 19 Jun 2025 15:12:52 +0100, No mail <nomail@aolbin.com> wrote:

I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an option
(because part slides in C.I. supports and bushes aren't feasible). Many
years ago I had success with oil blackening of small parts but I'm
dubious about being able to get the whole rod up to an adequate
temperature before it takes the plunge (I can make a suitable bath using
a bit of C.I. guttering that's in the useful bits pile).
Has anyone got any words of advice, or a room temperature process to
suggest?

You may be able to get away with oiling the steel and then heating it with a blowtorch, bit by bit. Maybe wipe extra oil on with a thick wadded rag.

Or look at tannic acid: tannic acid in IPA, wipe on, wait overnight. Deep black.

Some rust converters are tannic-acid-based.

Thomas Prufer

'Curust' will turn rust black.
There are black wax treatments and paints for wood stoves etc that are amazingly resilient


--
“it should be clear by now to everyone that activist environmentalism
(or environmental activism) is becoming a general ideology about humans,
about their freedom, about the relationship between the individual and
the state, and about the manipulation of people under the guise of a
'noble' idea. It is not an honest pursuit of 'sustainable development,'
a matter of elementary environmental protection, or a search for
rational mechanisms designed to achieve a healthy environment. Yet
things do occur that make you shake your head and remind yourself that
you live neither in Joseph Stalin’s Communist era, nor in the Orwellian utopia of 1984.”

Vaclav Klaus

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Thomas Prufer wrote:

On Thu, 19 Jun 2025 15:12:52 +0100, No mail <nomail@aolbin.com> wrote:

I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an option
(because part slides in C.I. supports and bushes aren't feasible). Many
years ago I had success with oil blackening of small parts but I'm
dubious about being able to get the whole rod up to an adequate
temperature before it takes the plunge (I can make a suitable bath using
a bit of C.I. guttering that's in the useful bits pile).
Has anyone got any words of advice, or a room temperature process to
suggest?

You may be able to get away with oiling the steel and then heating it with a blowtorch, bit by bit. Maybe wipe extra oil on with a thick wadded rag.

Or look at tannic acid: tannic acid in IPA, wipe on, wait overnight. Deep black.

Some rust converters are tannic-acid-based.

Thomas Prufer

An interesting idea. I have some Fertan, which I believe is based on
Tannic acid, but the blurb says it needs over-painting.

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The Natural Philosopher wrote:

On 20/06/2025 09:56, Thomas Prufer wrote:

On Thu, 19 Jun 2025 15:12:52 +0100, No mail <nomail@aolbin.com> wrote:

I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an option >>> (because part slides in C.I. supports and bushes aren't feasible). Many
years ago I had success with oil blackening of small parts but I'm
dubious about being able to get the whole rod up to an adequate
temperature before it takes the plunge (I can make a suitable bath using >>> a bit of C.I. guttering that's in the useful bits pile).
Has anyone got any words of advice, or a room temperature process to
suggest?

You may be able to get away with oiling the steel and then heating it
with a
blowtorch, bit by bit. Maybe wipe extra oil on with a thick wadded rag.

Or look at tannic acid: tannic acid in IPA, wipe on, wait overnight.
Deep black.

Some rust converters are tannic-acid-based.

Thomas Prufer

'Curust' will turn rust black.
There are black wax treatments and paints for wood stoves etc that are amazingly resilient

Yes, the first reply suggested Zebo. I think I'll try Fertan, followed
by Zebo. If that fails I'll buy one of the kits from Blackgates or Chronos.

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On Fri, 20 Jun 2025 17:05:46 +0100, No mail <nomail@aolbin.com> wrote:

Thomas Prufer wrote:

On Thu, 19 Jun 2025 15:12:52 +0100, No mail <nomail@aolbin.com> wrote:

I need to "black" a 600mm long 8mm mild steel rod. Paint isn't an option >>> (because part slides in C.I. supports and bushes aren't feasible). Many
years ago I had success with oil blackening of small parts but I'm
dubious about being able to get the whole rod up to an adequate
temperature before it takes the plunge (I can make a suitable bath using >>> a bit of C.I. guttering that's in the useful bits pile).
Has anyone got any words of advice, or a room temperature process to
suggest?

You may be able to get away with oiling the steel and then heating it with a >> blowtorch, bit by bit. Maybe wipe extra oil on with a thick wadded rag.

Or look at tannic acid: tannic acid in IPA, wipe on, wait overnight. Deep black.

Some rust converters are tannic-acid-based.

Thomas Prufer

An interesting idea. I have some Fertan, which I believe is based on
Tannic acid, but the blurb says it needs over-painting.

Try it -- I have not overpainted it, but coated it with wax heated and rubbed on. Looks good, sufficiently stable for my use.


Thomas Prufer

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