Thread: Blueing - rust and removal

A 5 gallon bucket, Approx1/4 cup borax soap, battery charger, water, scrap wire or coat hanger. Important keep the metal part being cleaned and scrap metal separated. Wrap part being cleaned with a little wire hook it to the negative battery charger clamp. Hook wire to scrap metal and positive battery charger clamp. Use low trickle setting for a few hours depending on severity of rust.

The problem with this method is that it alters on the rusted sections and leaves the tool looking blotchy.

Old school metal bluing or blacking deliberately generates a very thin fine patina of red ferric rust over the entire item and then converts this to black Ferrous oxide.
I reckon it looks much better than just attacking the rusted sections. The one bugbear with old school bluing is that it takes a Looooooooong time.

Have a look at this thread. https://www.woodworkforums.com/f65/my...bluing-155843/

Originally Posted by woodhog

A 5 gallon bucket, Approx1/4 cup borax soap, battery charger, water, scrap wire or coat hanger. Important keep the metal part being cleaned and scrap metal separated. Wrap part being cleaned with a little wire hook it to the negative battery charger clamp. Hook wire to scrap metal and positive battery charger clamp. Use low trickle setting for a few hours depending on severity of rust.

Sure - but as soon as you take it out of the solution it starts to rust again, and real fast too as the exposed steel is very clean. Yes you can put a bit of oil or other protection on it but how long does that last. Clinton is after something more permanent.

Can I suggest a small sanded section to get just phosphoric acid, left for 5-10min until it dries, then cleaned off and covered with lanolin?

That basically describes my 888 'project' saw ... and has surprised me on the back verandah with how un-effected by the conditions it is compared to other saws that are waiting for some attention eventually. But so is another one (D23) that I haven't fooled with, so it could be down to the metal in the blade.

Also it is not salt-air around here.

If you can fit it into your trial, great. In any case - I'll be very interested in your work.


Cheers,
Paul

PS ... phosphoric on an etch (that you'd like to keep) is ... unhelpful ... d.a.m.h.i.k.

Bob,
I just quickly followed your links.
You are an absolute blueing and coffee water purification nutbag (meant in the nicest and most absolutly admirable manner)!!! I wish you lived near me. <insert - serious, I mean this, take me seriously, smilie>

Your comments make me think that you should take over this thread, and your '2nd attempt blueing' thread proves my point. Good Job!
The trouble is, as you pointed out, that 'old school' blueing and Parkerizing takes way too long (for me), and has a more complicated process. On the other hand, 'cold blueing' presents a surface appearance problem... a process of accepting trade offs and acceptability of results.
Might I respectfully suggest that your method is way too slow and complicated for me to undertake.... but I'll be wrapt if you accept all my tools for processing to your standard of blueing.

Woodhog,
Yep, with you 100%.
Electrolysis seems remarkably easy, after you have done it you wonder what you were worried about. I am a big fan of electolysis.
Then... rust.... creeps.... in... damn it.

Paul,

phosphoric on an etch (that you'd like to keep) is ... unhelpful

IME, Not really, depending, sorta. (I'll try not to tie myself into knots explaining this)
1. An etch is an etch, an engraving is not an etch. IMO the difference is the depth that the pattern is 'cut' into the surface. Etch = shallow, engraving = deeper. (Peter/Lightwood feel free to step in here!). I'll go out on (another) limb and say that the difference is that an etch is cut by the acid that colours the resulting etch, and engraving is cut with a tool.

2. Preserving or attenuating an etch is where the next step in blueing, a Selenious acid mix, steps in. (well, one of the possible steps) The enemy of etches is acid left on too long and over-agressive sanding, IMO.
In other words, the best way to stuff up an etch is to remove it either/or chemically or with abrasive, e.g. remove the metal that surrounds/envelopes an etch, removing the etch in the process.
Remember that an etch is just a scratched steel surface that has been blued, and then the blue scrubbed off/removed from the area surrounding the etch, the etch contrasts with the shiny surface, hence it looks cool.
So if you have 95% of an etch to work with, you can raise it easily.... if you have 5% remaining, then reconsider your options. If you have 95% of an etch and you use a really strong acid solution, for a long time or often, and then scrub the whole area with abrasive... then be content with your etch free saw.

Any traces of an etch can be 'raised', results depend on the traces you have to work with.
(note to self - introduce the rust 'volume change' issue and how that affects things)

After raising an etch, you need to decide to continue blueing or not. The result of further blueing hides the etch as the blued surface and the etch will be almost the same colour. Don't continue blueing and you have a shiny saw with a good etch that sucks in rust like a lovelorn teenager sucks in sympathy and attention.

I'll do my best to accomodate your test suggestion, and I'll also see if I can meaningfully fit in 'raising an etch'... might need a second saw tho.

You make me think that I should explain why I use different acid solutions at different stages.... a bit of backtracking may be required... but if I was smarter, my posts would be shorter... yet more trade offs.

Successfully tied myself into a knot.... off to bed.

Yep I admit I am a nutbag. I agree that cold acid bluing is extremely time consuming and I would only do that for something that was really worth doing

If you are looking for quicker and dirtier solution here are a couple I have tried with mixed success.

Following electrolysis wash in clean water and blow dry with a compressor and hang object so it dries and rusts, yes rusts. The aim is to get as even a layer of rust on it as possible so if the object had hollows etc make sure the water had been removed. Then apply the phosphoric acid and it will look a lot more even than just applying the H3PO4 to the rusty bits.

One problem with using H3PO4 is that it absorbs water in a humid atmosphere and it is sometime very hard to get dry and even when it is dry can become sticky later on. I have light baked H3PO4 coated tools at ~150ºC in a BBQ which dries them out and turns the residue grey which does not seem to reabsorb water as much as the unbaked objects. For tools where temper doesn't matter I have taken the temperature up to 240ºC, this turns the residue a light grey - this seems to be reasonably protective - at least as protective as the atmospheric dried H3PO4 but without the stickyness.

So, seperating electrolysis from the mix may be best.

Electrolysis article here I'd strongly recommend that if you have not done electrolysis before, that you read it, at the least for the safety info.

Electrylosis set up... trickle charger with red/+'ive connected to sacrificial metal.
Black/-'ive connected to rusty tools using a gang method.
Tank filled with water and some bath salts.

Backsaw blade connected to the lead wire and about to be suspended and connected to the load.
You can see that this was cleaned before, and then there is another layer of red rust appearing.

DSC_6807.jpg

A close look at this side shows how badly areas have been 'pitted' from previous rust. Rust occupies more volume than the iron it replaces. This saw must havee been rusting away for a long time to get this pitted. Cleaning by previous owners has removed this rust, but inadequate oiling and storing has brought on a new rust layer. Yah!
DSC_6806.jpg

After a few hours the glumpy red foam appears.

DSC_6804.jpg

After hours in the bin I notice that the foam does not clear from around the anode and cathode.... to me this means no bubbles forming from the process = the process is over.

Remove the item, wash off under the hose, then give it a good scub with steel wool and soapy water to ensure that no 'loose particles' remain.
From here I could just oil the tool and be finished.
Any further scrubbing or abrasive just burnishes the surface, or if you go too far will abrade the surface back to bare steel.

The electrolysis article linked above has good pics of items 'finished' at this stage. The electrylosis process leaves 'black iron' oxide, Fe3O4, a stable iron oxide (magnetite).
This surface will turn rusty over time as the layer is worn/scratched, and attacked by the usual rust casuing agents.

One way of using Cold Blueing (simple blueing in my terms).

One way I use blueing is to blue over the cleaned electrolysis item.
This allows me to a) build a protective finish on the cleaned item (e.g. complementing the electrolysis layer), b) create uniformity of appearance, and c) help protect from further rusting.

I just use a Cold Blue solution (MSDS here) which is @3% each of Selenious acid, Nitric acid and Copper Sulfate, the rest water.
Again, I use this brand is just handy to purchase and use, e.g. it is what is stocked locally.

After the cleaning described aabove, I clean it with a cloth and degreaser, then re-wash under water. and dry.

Using a swab, coat the surface with the blueing solution. Following the safety precautions and instructions is a good idea.

After a minute or so, I wash off under water, inspect, and then use fine steel wool to scrub the darker areas into the lighter areas.
This helps to even out the surface appearance.

3 coats is usually enough.
Final wash, dry and then a light oil with a cloth, then a heavy oil with heavy pressure on a cloth. e.g. little oil, then a lot pushed into the surface.
Hang overnight to 'cure'.

Pic shows results on the backsaw blade.
I'll draw your attention to the colour of the area that was under the back, e.g. after electrolysis and abrasive scrubbing this area was shiny bright.
Now it is a nice dark blued colour and is both protected from further rust and colour matches the rest of the saw.

The back was done in same manner, and I think that it looks quite good, as well as now being more resistant to rust.
For perspective, the back is 1" in width, and is leaning up on a house brick.

Abuse time:
From here guess I will degrease the blade, salt some of the surface to promote agressive rusting/abuse, leave some unsalted and unoiled, and oil the rest of the blade. This will provide perspective on the effect of blueing and its rust resistance.

DSC_6855.jpg

Both saws treated with electrolysis and sanded in the usual manner, large saw cold blued both sides, oiled, then hung on the clothesline for @4weeks. Weekly oiling with a rag.

Small saw electrylosis treated, blued on one side only, oiled both sides, hung on the clothesline for @4 weeks. No futher oiling.

Results speak for themselves.

DSC_7030.jpgDSC_7031.jpg

Thanks for the progress report. Maybe it is that a chemical protectant has it over any liquid/waxy coating .

Here's my typical WD40 experience: https://www.woodworkforums.com/f152/w...ml#post1646727

Cheers,
Paul

Another 6 weeks with the saws hanging off the clothes line. Its been a wet 6 weeks here in Sydney.
(also, I get salt laden southerly's making a contribution)

6 weeks ago, I dipped both saws in the salt water bay I live across from.

The large saw continued to be oiled weekly - pic not shown as there is no change at all, e.g. maintaining its original (rehabbed) condition.

Small blade (never oiled) is starting to show rust on the cold blued side.
Un-blued side is showing rust 'scales' with pitting under the rust.

After @10 weeks of weathering, I'm going to 'close off' this experiment.

I'm happy with the results and with the 'safety/oh&s issues' and ease of application, as well as the ease of removal of the blueing (sand it).

Thanks to Bob Smalser for his article on blueing which first brought the issue to my attention.

For those that are interested.

I'm moving house and found the test saws hanging outside - another 8 months in the weather.

Right saw was derusted (chemically) and oiled, middle de-rusted only. Left was de-rusted by electrolysis and blued and oiled.

None were touched over the last 8 months and were left out in the weather.

Bluing is holding up nicely. Later in the year I think I'm going to blue every bit of bare metal I can.... I hate rust.

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