Darkening cast iron?

Re: Darkening cast iron? *LINK*

Gary Smyth

There is a chemiical by epi electrical products #404 https://www.epi.com/contact/

Never tried it. Only found by search on Google.

Muriatic acid gives a rust to black variation but not pure black.

The Blackening Process: Ultra-Blak 404

For the longest-lasting, deepest, and cleanest black finishes, we recommend the following blackening process. Please read all safety data sheets and technical data sheets prior to beginning a project.

1. Clean

Soils such as cutting oils, coolants, lubricants, and rust inhibitors must be removed from the metal workpiece. Soils can inhibit the blackening process and negatively affect coating adhesion and appearance. Thoroughly clean and degrease the parts prior to beginning the blackening process.

Recommended Cleaning Products:

E-Kleen SR 102-E emulsifies oils and cleans difficult-to-clean metalworking fluids and carbonaceous smut.

E-Kleen SR 102 floats oils, cleans difficult-to-clean metalworking fluids and carbonaceous smut, and results in a longer-lasting clean.

E-Kleen SR 196 is a low-caustic cleaner that floats the oil, resulting in a longer-lasting clean. It's effective up to 210º F.

2. Rinse

After cleaning the metal parts, rinse them in cold, overflowing tap water; it’s necessary to rinse the parts to remove residual cleaning solution. Parts carrying over un-rinsed film of alkaline cleaning solution would quickly contaminate the subsequent chemicals in use, resulting in a spotty or non-adherent black finish.

Immerse the parts to be blackened for 30–60 seconds.

3. Activate

Activate the metal parts in hydrochloric acid (50% by volume) for 30–60 seconds.

4. Rinse

Rinse in cold, overflowing tap water for 30–60 seconds.

5. Blacken

Immerse the parts in a boiling solution of Ultra-Blak 404 until a deep black color develops. Required immersion times may vary from 5–10 minutes, depending upon the mass, type, and surface condition of parts.

If Ultra-Blak 404 isn't quite what you’re looking for, consider these similar products:

Insta-Blak 333 is an easy-to-run, room-temperature blackening process that saves energy.

Ultra-Blak 404-L is the liquid version of Ultra-Blak 404, which makes it safer to add to a blackening tank.

6. Rinse

Rinse in cold, overflowing tap water for 30–60 seconds to remove residual blackening solution and ensure sealant will not be contaminated.

7. Seal

Seal the black-oxide finish by immersing the still-wet parts in a corrosion-inhibiting and rust-preventative solution. E-Tec corrosion inhibitors are formulated to rapidly displace the residual acidic solution from the preceding rinse and produce long-term corrosion protection. As the E-Tec is absorbed, it enhances the depth of black, which may take several hours.

Recommended Sealing Products:

E-Tec 504 is a solvent-based, water-displacing rust preventer that results in a hard, dry finish.

E-Tec 510 is an economical, water-soluble oil that offers rust protection and contains no solvents.

E-Laq 525 is a water-based lacquer that offers a hard, dry, and corrosion-resistant finish.


/https://www.epi.com/contact/

Re: Darkening cast iron? *LINK*

Bruce, a MN Galoot

I just saw this recommended on a machinist’s forum


https://surfinchemical.com/collections/all/steel-and-iron

Re: Darkening cast iron?

JohnV

sulphuric acid (sold in hardware stores as drain opener) works well Easy to use, just brush on let stand for a few minutes then rinse we;ll. Be sure to wear protective clothing including face protection and gloves. Do outdoors . It is nasty stuff but works well.

Re: Darkening cast iron?

Derek Cohen (in Perth, Australia)

Jim, Gary and Bruce ... I looked at the products for blackening, but they do not deliver to Oz.

I've been looking into bluing, but I gather that is is not durable. Is this so?

John's suggestion of sulphuric acid is worth trying, unless I can get a less risky method.

Regards from Perth

Derek

Oil Blackening

Ken Vaughan

Got a blacksmith or bladesmith you know handy?

Heating iron very hot and applying oil (or dropping in a bucket of oil) is an olde olde way to get a black surface.

electrolysis?

Bill Tindall, E.Tn.

cleaning with electrolysis leaves metal black. Unsure what would happen on unoxidized surface but it is trivial to try if you have a car battery, some wires and washing soda or lye.

Re: Darkening cast iron?

Bill Tindall, E.Tn.

The only permanent durable black will be from creating a surface coating of oxidized iron in the proper oxidation state. In the gun trade it is called "blueing". It is created by immersion of steel into an hot oxidizing material. No idea if it works for cast iron. In the US you could find a gun smith to do it and maybe the same in AU. You can get a good black on steel from simply heating to create this oxide but I don't remember the temperature (it is hot, maybe 600C). But this black is not thick. It is protective to corrosion but not wear.

To get black hardware I use "black bronze". I like the luster and it is durable.

Re: Darkening cast iron? *LINK*

Bruce, a MN Galoot

I just ran across this. Go to 10:50 and watch what Torbjörn Åhman uses for a finish.


Torbjorn Åhman blacksmith

Another option?

Bill Tindall, E.Tn.

Iron phosphate is black and resists corrosion. Treatment of steel, again is cast iron different??, with phosphoric acid yields a black adherent coating. But I think it would have to be protected with lacquer or some such for durability.

Re: Darkening cast iron?

Jason in Denver

I used the baked-on flaxseed oil method on my bench hardware. It produces a nice dark brown but not black.

Re: Darkening cast iron?

Bruce Schoenleber

Just like seasoning a cast iron pan or a wok. Coat with veg oil or PAM and place in a 400 degree F oven for an hour. Repeat a few times.

Re: Darkening cast iron?

Derek Cohen (in Perth, Australia)

Here's where I am at this stage:

I have cast iron knobs for the chest I am building. The are silver-light grey in colour. I would like them to be charcoal-to-black.

The issue with cold bluing formulations is that they create a finish that wears with handling. Drawer knobs get handled frequently (although these should not get daily use).

Hot formulations are more durable than cold formulations. I have a good friend who is clued up on the chemistry of these products. I mentioned that I had ordered a stove polish. This is rubbed on and then the iron/stove is heated. Lots of smoke issue, and then the finish gets rubbed back. He said that this is equivalent to the hot formulation, and should be durable.

This is the product I have ordered ...

https://www.rubbedin.com.au/Product/26/Fuel-Stove-Range/Cast-Iron-Stove-Polish#horizontalTab1

I ordered one extra knob, and will experiment on that when the polish arrives.

Regards from Perth

Derek

Re: Darkening cast iron?

Bill Tindall, E.Tn.

I studied the safety sheet for the product and it is certainly not a "hot bluing" preparation. I suspect it is some sort of oil that gets pyrolyzed and turns black, not unlike "Japaning". It contains silica, likely as a filler. It will be interesting to see how it performs long term. I would think it trivial to recoat when needed.

Re: Darkening cast iron?

Derek Cohen (in Perth, Australia)

Thanks Bill

Yes, not a bluing product - I admit to generalising the process. The essense is hot vs cold treatments.

Thanks for the clarification, nevertheless, and especially your analysis of anticipated results.

Regards from Perth

Derek

hot bluing doesn't seem hard

Bill Tindall, E.Tn.

You perked my curiosity so I looked up the hot blueing (actually blackening) process. It would be easy on small parts, not so easy on a long gun barrel. Any full service gun shop should have the capability. There is no doubt that is what I would do, but then, I love doing chemistry experiments.

The desired product is Fe3O4, a stable black oxide of iron that is very hard and resists further rusting. You get it by oxidizing iron, some how. A thin layer can be had just by heating in air (fairly hot but I don't remember how hot.) I did it in a lab furnace. A thicker layer can be formed by immersing the metal in an oxidizing solution, in this case nitrate either from sodium, potassium or ammonium nitrate. The conversion of ammonium nitrate to sodium nitrate by sodium hydroxide produces inconvenient amounts of ammonia (you could fume some oak at the same time) and the internet recipe does not account for the loss of hydroxide to make this conversion. Whether any of this works for cast iron instead of steel, I don't know.

Brass looks best on walnut. I would not be using iron to begin with. Iron looks good on old English oak and Medieval furniture.

http://www.guntechtips.com/bluing/bluing.htm

Re: hot bluing doesn't seem hard

Derek Cohen (in Perth, Australia)

Brass looks best on walnut. I would not be using iron to begin with. Iron looks good on old English oak and Medieval furniture.

Bill, I like brass on dark woods, but this chest is a contemporary version of aapothecary chest, which will become more apparent when I build the stand.

The knobs are what I would call "Modern Shaker". I hunted all over for these. I was going to turn them in walnut or ebony, and then came across them in a UK store.

The smallest ones ..

The finish currently is lighter than this. I hoped for a little darker. I am not so sure about black any longer - I think that I will try them as is first, and then decide whether to blacken the knobs.

Regards from Perth

Derek

love the shape

Re: Another option

Larry Clinton At Frankfort, (Central) Indiana

Many firearm enthusiasts coat their firearms and accessories using Cerakote. It is a spray-on finish with ceramic particles and is Very resistant.

It is available in spray cans in Matte black and other colors and can be purchased as a finish requiring baking at 300F to cure (the most resistant to wear) or as an air dry finish. It is available in aerosol cans.

Most coating offered are matte finish, unsure if gloss is available. It certainly would be more than durable enough for your application in either baked or air dried!

It is available at Amazon - think you could get in in your country.

https://www.amazon.com/Cerakote-Fire-Arm-Coating-Armor-Black/dp/B00GUN04ZC/ref=pd_sim_328_2?_encoding=UTF8&pd_rd_i=B00GUN04ZC&pd_rd_r=6bb442a8-88f9-11e8-8ef3-63b7862c0680&pd_rd_w=QC7C9&pd_rd_wg=E9b4x&pf_rd_i=desktop-dp-sims&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=7967298517161621930&pf_rd_r=QNAFCDN8CTX9KXQTMXD3&pf_rd_s=desktop-dp-sims&pf_rd_t=40701&psc=1&refRID=QNAFCDN8CTX9KXQTMXD3

Re: Another option

John in NM

It would last better, certainly, but I've yet to see a paint finish that looks like anything but paint (including products like Cerakote).

I did wonder briefly if one could parkerize cast iron.... a bit more durable than bluing, but one has to know the chemistry well to avoid the greenish color that some parkerizing has.