Black protective oil coating

[Lindo]

I have made a few clamps for the mill table.
need to protect from "Rust".
I believe it's possible to heat up and dunk in oil.
Thinking of using my wood stove as the heat source,what color should the parts be when hot before the oil dip to achieve the blackening effect

Thanks
John
Spain

 

[Tin Falcon]

It depends if you want to color the parts or harden . Black heat is around 500 degrees. If you want to harden get it orange depend on the steel if it will harden.
tin

 

[Lindo]

Just to color,should act as a rust preventative I think.
and makes the parts look nice

John

 

[goldstar31]

Ola, Snr John.

This rust thing is really nothing to do with heating up steel plates and dipping them in oil of some sort.

True, you can colour but you can't prevent rust. As you live in Spain, you will probably have a paella pan which has had more hardened oil on it than you will get in a workshop- and it will rust.

Probably, the only way that you can minimise rust in the workshop is to phosphate the item and then put on some thing like paint or a wax.

Sadly, this colouring of metal and rust prevention are an old wives' tale that has occupied industry - since time immortal. Go into your local scrap yard. There will be at least one old Seat left and it will be a rust bucket. All the facilities in the Seat factory in Barcelona with fancy this and fancy that- will have failed. Audi, VW and Seat are now using galvanised parts.

On a more cheerful note( pun intended), I did enjoy your stuff on saxophones. Happily, my wife has a whole set and not a dent to be seen. Complete new ball game- she's just bought one of these plastic ones.

Salud, pesetas

Norman

 

[Omnimill]

I've had some success with steel by heating until the steel is deep blue/purple then dunking it in engine oil.

 

[goldstar31]

Agreed, agreed but my father and the rest of the tribe were all blacksmiths back to Shildon and Timothy Hackworth and his locomotives competing with George Stephenson and me, in a different sphere made coatings as one time- and everything rusted. Dad used to drop his hot metal into pitch and Uncle Harry used to coat his trials bikes in thick grease- but the answer was always the same.
I've got one of these double distinction things in tin bashing in a drawer somewhere- and nothing really works. #
We even had a brand new, top of the range Mercedes and I got two new front wings, two doors and a tailgate and four new alloys- and so on. Been there, paid me hard earned cash, wore out a few tee shirts and all that.

 

[gus]

Ola, Snr John.

This rust thing is really nothing to do with heating up steel plates and dipping them in oil of some sort.

True, you can colour but you can't prevent rust. As you live in Spain, you will probably have a paella pan which has had more hardened oil on it than you will get in a workshop- and it will rust.

Probably, the only way that you can minimise rust in the workshop is to phosphate the item and then put on some thing like paint or a wax.

Sadly, this colouring of metal and rust prevention are an old wives' tale that has occupied industry - since time immortal. Go into your local scrap yard. There will be at least one old Seat left and it will be a rust bucket. All the facilities in the Seat factory in Barcelona with fancy this and fancy that- will have failed. Audi, VW and Seat are now using galvanised parts.

On a more cheerful note( pun intended), I did enjoy your stuff on saxophones. Happily, my wife has a whole set and not a dent to be seen. Complete new ball game- she's just bought one of these plastic ones.

Salud, pesetas

Norman

Need your expert advice on hobby phoshating. Did eye witness the phosphating and spray painting 30 years ago.True .No Rust and the paint coat
sticks on like crazy.
Currently all DIY accessories and tools are sanded down to bare metal and coated with 2T Oil and kept on my Computer Desk in the bedroom which air-con at night. So far so good.

 

[goldstar31]

Greetings Gus for Christmas and our Two New Years!

As far as possible, the trick is to degrease- thoroughly. No oil, no grease or whatever. Bright shiny and-- clinically clean. Then you need phosphoric acid- and probably mixed with hydrochloric and sulphuric acids. I would guess that a good professional motor factors will have something that the real guys use to prepare steel body work prior to painting. It will etch into the steel and you will need to dry it with a heat gun. You then need either a zinc based or chromate based primer to effectively keep out the damp and you then can put on primers and finally the finish coats of paint- and if you can a good wax based preservative. It doesn't stop rust but you will get long lasting stuff.

To reminisce, Rolls Royce used to put on 22 coats of brushed primer- rubbing down every two coats and then put on about 14 to 18 coats of finish- again rubbing down every second coat.

The legend was that the foreman used to come in on a Saturday morning, sprinkle the floor with water to settle any dust and after he had thrown the cat out, did the final coat of paint.

Today, paint is water based but it is baked on-rather like the old days of stove enamelling. I've scratched the big Audi. It is a silver one. I have to dig in to remove the scratched in dirt and then build it up level and then airbrush it and then after numerous buildings up, put on clear over base coatings.

Happily, I don't scratch my cars very often but you can see just how much hand work is required to achieve a finish.

 

[Tin Falcon]

Lindo :

I will attempt to simplify things here.
I have done the oil dip things a couple times with knurls heat red hot with a torch dip in used motor oil brush clean then re oil.
I have done similar with blacksmith scroll work projects. heat to black heat then coat with wax.
by black heat I mean take a shinny piece of steel and heat until it turns blue to dark gray.

But beware this will soften hardened steel.
But to answer your original question you will need to get to the 700 -800 degree rance to obtain black heat.

the other methods are to use a chemical conversion most tool suppliers industrial supply houses have tool black.
Beechwood Casey the maker of gun blue for home uses also sells tool black.

In any case you are creating a layer of black oxidation to prevent brown oxidation from happening. so store in a wooden tool chest oild oncein a while and this will prevent rust.

tin

 

[gus]

Hi Tin,

Will try your blue/black method and dip into motor oil.
Years back found a rust preventive/preservative but my skin reacted badly.
WD-40 doesn't work well .
Meanwhile DIY tools which were sanded down to bare metal,polished and oiled and stored
in-door on my PC Desk have not rusted but occasional maintainance required.

This thread been very useful and interesting. Done blue-ing in Trade School but never as good as the gun smith.

 

[GWRdriver]

Over the years I've had very good (ie, rust resisting) results blacking steel with oil but the secret is to use very dirty oil, as dirty and carbon & contaminate-saturated as can be had. I have a very old lawnmower which I flog mercilessly and rarely change the oil in which provides me with a supply of blacking oil. It makes a horrible stink, when I quench, but the stinkier the better.

 

[Lindo]

Tin
Useful colour/heat chart Thanks.
Checked out Birchwood Casey products,not sure if they will ship to Spain from the UK,but have asked the question.
What do you think about painting with high temp paint,as used on restoring old BBQ's ,steel ovens etc and then
bake at about 200 degrees C.
possibly thin the paint down with 20% solvent.
If you buy a set of mill clamps (Chinese type) for example,what are they using to create the black finish?

John

 

[Swifty]

Mill clamps etc are most likely done in a heated black oxide bath, had a lot done when I was working. I have a home kit for black oxide treatment, it works really well. Consists of a degreaser, etcher, blackening and a soluable oil bath to finish. In between each bath is a clean water bath. All concentrated solutions, as purchased, are mixed with water and I have found that they don't go off. I have been using the same baths for 10 years and just occasionally add a bit more concentrate. My set up is in 4 X 2litre buckets with lids, I use any clean container for the water rinses.

Here is a link to a list of world distributors. http://www.blackfast.com/distributors/

Paul.

 

[Gedeon Spilett]

I do often steel blackening by diping in oil, I use it for protection or just as decorative mean. You can easyly obtain most of the coulours shown on the pretty chart above, but they change rapidely without a dedicated oven.
But of course, unwanted effects on hardness may occurs with carbon steel.
I agree with a previous post : dirty oil seems protect better against rust.
Clean parts, dirty oil and homogeneous heating are the secrets.
The blackened baseplate of my last tiny steam engine don't rust, as compared to other steel parts (already derusted!)

 

[Wizard69]

Interesting thread!

I've used cold blacken compounds with mixed results. I'm not sure why but following the directions seemed to make the blackening worst as I got blotches or uneven blackening. The thought I have right now is that the water is to hard to use in the cleaning process. Not sure really.

I'm considering alternatives to blackening though and have to ask if anybody has experience with the various spray on and bake gun finishes? Here I'm thinking Cerakote, DuraKote, Gunkote, Molykote and the like. In most forms these are spray on and bake coatings that require sand blasting or parkerising before the finish is applied.

My first problem is that I don't have a sand blaster so comments from others that have actually used these coatings on tools would be helpful. Otherwise I would have to go out and buy yet more tools with money I don't have at the moment. Not to mention an oven and the other goodies to apply the finishes.

By the way these finishes aren't cheap at all so probably are best reserved for high value tools and creations. If they work well it would be worth it on at least some things we make. I find the rust control issue to be very frustrating so new tech would be welcomed if it works well.

 

[Swifty]

I've found that with the water based cold blackening solutions, it is important that the parts are oil free. I generally wash the parts with acetone or methylated spirits before they go into the degreasing bath.

If you check out this post, scroll down a bit and you will see the results that I get with the blackening solution. http://www.homemodelenginemachinist.com/f13/er20-5c-adaptor-20647/

Paul.

 

[mecanotrain]

Hello All,
As Gedeon Spilett ( hello François !) said, I burnished steel heating behold my method:
I put the parts on a hotplate (1500W) with an electronic controller (home made)


I heat units at 400 ° C for 25-30 mn


I dip the pieces in oil drain VERY BLACK.

Here is the result with 3 parts:

 

[Wizard69]

I've found that with the water based cold blackening solutions, it is important that the parts are oil free. I generally wash the parts with acetone or methylated spirits before they go into the degreasing bath.

If you check out this post, scroll down a bit and you will see the results that I get with the blackening solution. http://www.homemodelenginemachinist.com/f13/er20-5c-adaptor-20647/

That is outstanding compared to what I got. Do you remember the brand for the blackening agent?

Paul.

Thanks for the hint! I had scrubbed the part with the supplied cleaner but did not try acetone before that. The agent I was using was a gel like substance. Now that you have me thinking I'm wondering if my handling between stages left oils from the skin on the parts. I'm almost certain it wasn't me though, which is why I wondered about hard water.

I think the next time I will look for a dipable agent.

 

[Swifty]

Use the link in post 13 to find distributors for Blackfast solution. I purchased my initial kit over 12 years ago for about A$125, even if it's double that nowadays, it's well worth it.

I may do a separate posting showing how to use the solution and the time it takes.

Paul.

 

[goldstar31]

I think the next time I will look for a dipable agent.

If you read my posts , I was emphatic about 'clean' and used the adjective 'clinically'. Whilst I used acetone and a lot of even more dangerous substances, the ordinary man in his shed might not/cannot access these items and two easily obtained cleaners do the job reasonably well.

We used to boil out the crap/ gels and whatevers that were burnt on with 'cows dick' or boiling strong solution of caustic soda which acted like soap.

Again, todays cure- the cheap and easily obtained one is- the common or garden household dishwasher- which uses largely salt.

Wandering off course, are those famous beasties called fish eyes- from silicones. Of the record even further was the paint problem of the Hillman Imps-- and the wrong water.

Big, big topic. I'm merely scratching at the surface!