Tricky to clean pieces

[Karn3]

Hi all. I made these the other day to hopefully be a pair of bookends. At the time though, I didn't really think about how I would clean them up. As you can see from the picture, they're filthy. They've been sitting in my shop for the last few days after a couple of failed cleaning attempts. They aren't quite as bad as they look, for some reason my camera has accentuated all of the colours but they are pretty bad. What would be the best method for cleaning them, or any similarly difficult to clean pieces they might come out of my forge? Many thanks in advance.

[DSW]

I'd probably think about some sort of acid etching to remove rust and scale. Sandblasting would be my 2nd choice.

[ThomasPowers]

electrolytic de rusting if you have access to a car battery charger.

 

Otherwise soak overnight in household vinegar and thoroughly rinse in running water the next day.

[Kal]

I've used muiratic acid to clean an old badly rusted hammer head.  It had been sitting in a basement for years.  I was really surprised how well it turned out.  I just dropped it in a jar full.  One thing to keep in mind, the fumes from that stuff will rust everything in the shop and it isn't too good for your lungs either so do it outside.

[Karn3]

I'd probably think about some sort of acid etching to remove rust and scale. Sandblasting would be my 2nd choice.

 

I did try soaking it in some ferric chloride that I have. The places I could rinse with a towel came up nicely but there were still some places that I couldn't reach where the crap was obviously loose but still just sitting on the surface. Maybe I just didn't leave it long enough? I was a bit worried about potentially damaging the pieces. How long do you recommend leaving the pieces in acid?  

 

 

electrolytic de rusting if you have access to a car battery charger.

 

Otherwise soak overnight in household vinegar and thoroughly rinse in running water the next day.

 

oooooo, that sounds fun. How would I go about doing this? I have several car batteries available to me.

[petere76]

Kam3,

Vinegar, soak the pieces in plain old white vinegar. Leave overnight and the scale will fall off with some soft scrubbing. Rinse with soapy water when finished. Then you can prime, paint or otherwise finish the piece.

You can also set up a DC circuit and a salt bath, using a battery charger. Thus works great on heavily rusted pieces and old tooling you want to clean up. Just google electrolisis and pick the process that will work best for your situation.

Peter

[DSW]

I'd forgot about electrolysis. To do that you need some Arm & Hammer washing soda, a plastic container to submerge the part, a sacrificial anode, possibly some wire to connect the sacrificial anode and part to be derusted to the battery charger and a 12v DC charger. You add some A&H to some water in the plastic tub. I forget the rough proportions because last time I did it I used a 45 gall trash can and a whole box. Wire the part to the black (-) side of the charger and your sacrificial anode to the red (+) side. Make sure the part is completely immersed and the anode is almost completely Immersed ( try and keep the wire to the anode out of the solution or it will rot thru very quickly).

 

For the sacrificial anode, I used a 3/4" carbon rod for mine. If you use some junk metal like rebar  it k deposits a layer of rusty crud on the part that need to be washed off. The carbon rod leaves a layer of carbon instead. I found the pressure washer or a wire brush was the easiest things to use to remove that deposit while still wet.

[John B]

I'd forgot about electrolysis. To do that you need some Arm & Hammer washing soda, a plastic container to submerge the part, a sacrificial anode, possibly some wire to connect the sacrificial anode and part to be derusted to the battery charger and a 12v DC charger. You add some A&H to some water in the plastic tub. I forget the rough proportions because last time I did it I used a 45 gall trash can and a whole box. Wire the part to the black (-) side of the charger and your sacrificial anode to the red (+) side. Make sure the part is completely immersed and the anode is almost completely Immersed ( try and keep the wire to the anode out of the solution or it will rot thru very quickly).

 

For the sacrificial anode, I used a 3/4" carbon rod for mine. If you use some junk metal like rebar  it k deposits a layer of rusty crud on the part that need to be washed off. The carbon rod leaves a layer of carbon instead. I found the pressure washer or a wire brush was the easiest things to use to remove that deposit while still wet.

Have you got the polarity right?

IMHO red + goes to workpiece to be cleaned, black - on sacrificial piece, DC current flows from positive to negative I believe.

 

 If you got black and rebar/rusty crud deposits, in effect you were electroplating, not cleaning

 

you are incorrect, Electron flow is from negative to positive.

[doc]

Actually the flow of electrons is from negative to positive. Old Ben Franklin got it wrong and has been confusing the average guy about this stuff ever since. 

[windancer]

Warm vinegar and hot water, 50/50.. overnignt. rinse with hose & spray nozzle.

Repeat if required.

Dave

[thingmaker3]

"Anode" means"positive." "Cathode" means"negative." :)

[DSW]

Have you got the polarity right?
IMHO red + goes to workpiece to be cleaned, black - on sacrificial piece,

 
Nope I'm pretty sure I got it right. I double checked a couple other places and they all seem to be agreeing with what I remember... I may have Cathode/anode wrong but I've always heard the sacrificial part known as an anode.
 
http://www.stovebolt.com/techtips/rust/electrolytic_derusting.htm
 
From above...

THE POLARITY IS CRUCIAL!! The iron or stainless electrode is connected to the positive (red) terminal. The object being cleaned, to the negative(black). Submerge the object, making sure you have good contact, which can be difficult with heavily rusted objects. Get it backwards and your object will be relentlessly eaten away! Make connections on a part of your electrode that protrudes out of the solution, or your clamps will erode rapidly.

 
http://www.instructables.com/id/Electrolytic-Rust-Removal-aka-Magic/?ALLSTEPS
 
From above...

You hang your rusted tool in the solution and attach it to the negative end of the power supply. You attach the positive end to the anode and turn on the power.

 
 
http://myweb.tiscali.co.uk/andyspatch/rust.htm

[JNewman]

Two other options are

1. Get a really good coating of rust on them then rub a good coating of wax into them with a non abrasive scotchbrite type pad ( I have not done this so test on some scrap first). personally not my cup of tea but I have seen some rust finishes that had wax or something rubbed into them that actually looked pretty good almost like leather.

 

2 throw them back in the forge and get a real good coating of scale on them, rub off anything loose with a wire brush while hot.  You may need some smaller brushes or just use the ends of the bristles stabbed into the holes.  Once it cools carefully take some folded  80-100grit sandpaper and lightly sand off any loose scale  and create highlights.  Be careful not to over do it,  it will take a while with all those folds. Take some red scotchbrite and go lightly over the whole thing and then apply your favorite clear finish.    The hard scale that is left on the surface leaves a neat pattern. 

 

Pickling which I do like for lots of things will give you a very uniform surface but I think you may have a hard time drying it off after rinsing due to the shape which means you will end up rusty again. 

[Frosty]

You can dilute Naval Jelly about 50% in clean water and soak the pieces. Be sure to neutralize and rinse well, real well when it's finished. If naval jelly dries the phosphoric acid will leave a black phosphate oxide(?) finish.

 

Frosty The Lucky.

[John B]

Nope I'm pretty sure I got it right. I double checked a couple other places and they all seem to be agreeing with what I remember... I may have Cathode/anode wrong but I've always heard the sacrificial part known as an anode.

 

http://www.stovebolt.com/techtips/rust/electrolytic_derusting.htm

 

From above...

 

http://www.instructables.com/id/Electrolytic-Rust-Removal-aka-Magic/?ALLSTEPS

 

From above...

 

http://myweb.tiscali.co.uk/andyspatch/rust.htm

 

 

APOLOGIES It would seem I got it wrong ! (it does happen)

 

to clarify and confirm

 

Black/negative to rusted piece to be cleaned and is immersed in solution

 

Red/positive to sacrificial material immersed, but not in contact with item to be derusted.

 

and thanks for putting me right.

[DSW]

Correct. Don't sweat it. I have to double check myself when I go to do this, and I wasn't even sure last night that I didn't screw up and mistype the original post, even though I'd gone back and checked my notes from the last time I did it. Hence why I posted up those links when I did some research to double check myself. That and I figured some of that might explain the process better to guys who had never done it before.

 

I vaguely remember doing a bit of plating back in Jr high metals shop. I want to say it was one or two days when they did a demo for someone whose project required it. As far as derusting. I started to do that within the last two years after seeing the results others were getting restoring old tools and equipment.

[ThomasPowers]

Drying off after rinsing:  rinse the last time with boiling water and slap the piece against a hard surface to dislodge any water left, dries quickly then...

[jeremy k]

along with the use of an air hose

[ausfire]

If you're not in a tearing hurry, submerge them in a 10% molasses solution for a couple of weeks. They'll come out spotless.