Thread: Blueing - rust and removal
15th April 2013, 05:07 PM #1
Blueing - rust and removal
I am a rust magnet.... my fingerprints rust onto metal in no time flat, I sweat a lot, I also live next to salt water.
I buy old tools and fix them up (to some degree of proficiency) and then use them. I have a 'collection' of old tools... they are all users and I do not have any precious 'mantlepiece' tools (actually, all my tools are mantlepiece items, 'cause they are old, have a fair amount of time invested into them, and work )
I am not meticulous enough to be chasing tools around with a waxed or oiled rag all the time. I am not a full time woodworker, so in the time I have to put to woodwork, I want to minimise the rust removal/prevention process as much as possible.
The other day, I pulled out a spokeshave that I hadn't used for a year or more, and even though the blade was sprayed in lanolin after use and then stored in a old timber cupboard... the back of the blade and edge is rusted.
I hate that. It means that I've pretty much got to go back to square1 and re-flatten/polish the back, re-do the edge.... blah blah blah. Rust sucks man.
IMO rust sucks.
I hate it.
But there is no magic bullet, IMO, rust happens and needs to be kept on top of.
But there are different ways to get rid of it and to keep on top of it.
Blueing tools is one way.
Here is my take on it.
Over the last year or so I've followed Bob Smalser's posts here on removing rust and then blueing tools. Blueing does not remove the need to oil tools, but it does provide added protection. Think 'belt and braces', or '...... and clingwrap'.
(a plastic bag, jokers!)
Demo - Rusted 1950's-ish saw, with @30% Phosphoric acid, @7% Sulfuric acid "Birchwood Casey Rust and Blue remover" dribbled onto it. MSDS here. I use this stuff as I can conveniently purchase it. Normally I would treat the whole surface equally, but for demo purposes, I've dribbled it willy-nilly.
Sprayed off with water.
80 grit paper applied to it, 20 strokes back and forward, then sprayed down with water.
Last pic is a closer detail showing the difference between the 'dribbled area' and un-dribbled area' after 20 strokes of 80 grit sanding.
This attempts to show that the acid treated areas 'shed' rust faster and there is the beginning of rust conversion.
Phosphoric acid reacts with rust to form a black ferric phosphate, which can be removed, or left on the tool to provide further (moderate) rust protection. In other words, the black ferric phosphate leaves a 'skin' which is a lower end form of rust prevention.
I'll keep working on one side of this saw with both abrasive alone and then 'phosphoric acid and abrasive', and post the end result.
I intend to treat the other side with electrolysis, clean the surface with abrasive, and post those pics. I'll try to spout off a bit on the effect and process of electrolysis.
Then I intend to blue one side and show the result.
Lastly, I will oil both sides of the saw and subject it to some abuse to see how an 'oiled side' versus a 'blued and oiled' side holds up.
I know that detailed pics will be hard, trying to capture the 'grain effects' and also the detail of 'what happens to the original etching' will be a challenge.
Hope this is of benefit so someone.
Chime in with your opinions, facts, experiences, dissenting viewpoints, spelling correcctions, rabid obsessions and whatnot, please. All welcome, if you think that rust sucks.
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15th April 2013, 05:32 PM #2Member
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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.
15th April 2013, 05:40 PM #3.
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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/
15th April 2013, 05:45 PM #4.
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15th April 2013, 05:57 PM #5
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.
PS ... phosphoric on an etch (that you'd like to keep) is ... unhelpful ... d.a.m.h.i.k.
15th April 2013, 10:54 PM #6
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.
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.
phosphoric on an etch (that you'd like to keep) is ... unhelpful
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.
15th April 2013, 11:27 PM #7.
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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.
16th April 2013, 02:30 AM #8
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.
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!
After a few hours the glumpy red foam appears.
16th April 2013, 05:56 PM #9
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.
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.
11th May 2013, 03:48 PM #10
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.
12th May 2013, 12:51 AM #11
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
29th June 2013, 02:21 PM #12
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.
3rd May 2014, 05:31 PM #13
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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