Millscale:
- Thread starter TurnipTruck
- Start date
I've been tempted to buy a gallon, bil regular old kitchen vinegar works fine for me. I've ruined a few times when I forget them for a day in the bucket
OP
TurnipTruck
Well-known member
I still don’t know what that coating was on the first table, but that 5% vinegar worked great on this side bench!
Overnight result:
Better than grinding!
I’m currently soaking both side benches with paper towels drenched in 30%. The 200cfm fume fan is running, and I have already found one brand of disposable gloves are better than another…
How are we neutralizing the vinegar? Just water flood? Or a baking soda/water concoction?
Overnight result:
Better than grinding!
I’m currently soaking both side benches with paper towels drenched in 30%. The 200cfm fume fan is running, and I have already found one brand of disposable gloves are better than another…
How are we neutralizing the vinegar? Just water flood? Or a baking soda/water concoction?
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OP
TurnipTruck
Well-known member
I sponged the vinegar off and rinsed a few times with water, and I can now touch the tables without getting dirty. I soaked everything in wd40 to knock down the flash rust.
It did take an entire day before the vinegar smell was gone.
I guess I need to mop all of the dust/oxide/**** from the floor, too.
It did take an entire day before the vinegar smell was gone.
I guess I need to mop all of the dust/oxide/**** from the floor, too.
DocsMachine
Well-known member
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- Sep 16, 2006
- Messages
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-Yes, definitely. I'd found vinegar-cleaned parts are more prone to rusting if only rinsed, rather than 'neutralized' and rinsed. I usually soak 'em in a bath of soda/water, but clearly that's not an option here.
I'd say mix up a small bucket of high concentration ('til the baking soda starts falling out of suspension in the water) and sponge it on, rinse, sponge/rinse, etc.
Dry thoroughly, hose with WD to stop the flash rust, start thinking non-drying oils you can wipe on, that won't be terribly flammable or contaminatory.
Doc.
housewolf
Well-known member
I know a thin coat of WD 40 is a popular choice to keep on a bare steel table but I had a qt bottle of shooters choice handy (CLP for guns) I wet the surface down pretty good and let it set overnight before wiping it dry. I’ve since spilled trans fluid, motor oil, and lord knows what else on it but it seems to be holding up fine and it’s been really humid here.
Cougar
Well-known member
We used a shot blaster for mill scale.
Would clean the part in about a minute.
Would clean the part in about a minute.
zhfabrications
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- Feb 6, 2023
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Pferd makes a diamond coated wire brush that is like $400 or so (I know it's crazy expensive), but it eats through mill scale like butter without damaging the parent material. I've had the same one for like ~5 years, and I would not hesitate to buy it again.
If you are using the paint removal disks make sure to run them low on a variable speed otherwise they will destroy themselves way too quickly.
If you are using the paint removal disks make sure to run them low on a variable speed otherwise they will destroy themselves way too quickly.
We never stripped the mill-scale from the tops of welding and worktables, it seems to work as a rust preventative and does not seem to interfere with conducting.
We used waste hydraulic to wipe them down occasionally.
We used waste hydraulic to wipe them down occasionally.
ericlar80
Well-known member
I wonder how a diamond disc grinder for concrete would work on mill scale.
Monza Harry
Well-known member
Diamond doesn't like carbon steel, and tends to plug up quickly when not used on hard materials [think carbide, concrete, etc. HSS isn't hard enough for metallic bonded Diamond wheels [Mill scale would be near(ish) to HSS hardness. I am not sure if these concrete wheels are metallic or resin bonded but the cheapest/cheaper wheels are a better chance of not plugging up do to the bonding agent but they would also have the finest grit size which would promote plugging. A test would be the only way I would be able to find out. Harry
metalmagpie
Well-known member
So much work to make pretty pretty steel. Then spatter stick like glue quick ugly ugly. Best to use cast iron for weld table top.
great white tj
Well-known member
I wish I had a complete before & after ‘cause the top came out so good, I painted the frame. Yea, cover the top & soak in vinegar, orbital sander with 60 or 80 grit then go over it again with 120
ETA: I found a (not very good) “before” pic
Are you coating your table with anything to prevent rust?
How long did you let it soak for?
OP
TurnipTruck
Well-known member
Because it seemed to collect dirt and couldn’t be cleaned thoroughly. Anything I set on the table got dirtier.
housewolf
Well-known member
I had some shooters choice (clp for guns) handy and figured it works on guns so why not? I put it on pretty wet and let it set overnight then wiped it dry. It seems to be holding up fine but I’m using the table daily so don‘t see it getting much chance to rust. If it notice it rusting I think wiping it down with a scotch brite and another dose of CLP or WD40 will keep it brite again for a while
I let the vinegar soak overnight
OP
TurnipTruck
Well-known member
There is some thought that it was a combination of tree sap/rust/epoxy and-or latex overspray/who-knows-what-else. It could be sulphide corrosion since it may have spent some time downwind of an elemental sulfur pit. It could even have been soaked in tetrachloroethylene cleaning up after an MCC explosion with lots of copper oxide soot, now that I think of it.
Anyway, it was filthy and seemed to adsorb particulates that couldn’t be swept off and I’d rather not brakeclean around welding arcs.
Anyway, it was filthy and seemed to adsorb particulates that couldn’t be swept off and I’d rather not brakeclean around welding arcs.
Well this needs some elaboration
great white tj
Well-known member
That is my welding table, the mill scale on the table keeps it from getting a good ground thru the top and the project I am welding on. I am in Florida and I hit the top with WD-40 and wipe it down. I use acetone to clean it from time to time..
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OP
TurnipTruck
Well-known member
Imagine, if you will, a certain heavy industry consuming approximately 20 Megawatts. Distributing that power throughout the plant are half a dozen Motor Control Centers (MCC), some 480v, some 480 and 4160v. These MCCs range from a utility trailer to a single wide mobile home in size. Outside each MCC is a large transformer knocking down from 25kv.
Instead of wires, between the transformer and the MCC 1600A main breakers(plural) and from the mains to the bus behind each rack are 14gauge powder coated steel panels enclosing three phase conductors each made of tripled 3/8”x4” copper bars bolted together with 3/8 bolts.
An unknown number of those bolts may have been left untorqued after a massive scheduled shutdown completed two weeks prior.
We will never know exactly if or how many, because a dozen feet of duct and conductors was found in a puddle that was still 1200*F four hours later by the SCBA-equipped fire team. The smoke was still so dense after four hours they used thermal cameras to access and assess the building.
Anyway, that smoke and vaporized copper & steel and asbestos tile had to be cleaned off the secondary breakers with carbon tet to determine reusability, and this table may have been one of the forty tables an army of electricians used.
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Chance
Well-known member
By "this table" you mean that melted mass of rusted iron? That was once a table top?Imagine, if you will, a certain heavy industry consuming approximately 20 Megawatts. Distributing that power throughout the plant are half a dozen Motor Control Centers (MCC), some 480v, some 480 and 4160v. These MCCs range from a utility trailer to a single wide mobile home in size. Outside each MCC is a large transformer knocking down from 25kv.
Instead of wires, between the transformer and the MCC 1600A main breakers(plural) and from the mains to the bus behind each rack are 14gauge powder coated steel panels enclosing three phase conductors each made of tripled 3/8”x4” copper bars bolted together with 3/8 bolts.
An unknown number of those bolts may have been left untorqued after a massive scheduled shutdown completed two weeks prior.
We will never know exactly if or how many, because a dozen feet of duct and conductors was found in a puddle that was still 1200*F four hours later by the SCBA-equipped fire team. The smoke was still so dense after four hours they used thermal cameras to access and assess the building.
Anyway, that smoke and vaporized copper & steel and asbestos tile had to be cleaned off the secondary breakers with carbon tet to determine reusability, and this table may have been one of the forty tables an army of electricians used.
OP
TurnipTruck
Well-known member
I am speculating that the filthy build-up on
“this table” from post #1
was caused by the chemicals used to clean up the residue after an electrical fire.
This chunk of (mostly) copper was later found underneath the suspected arc fault
and is the largest contiguous chunk of copper found. The central comb-looking thing is an asbestos arc-flash divider from inside a large 3-phase circuit breaker, and the brighter splashes near it is silver that melted from the breaker contacts. The phenolic from the breaker housing and the steel from the buss duct were turned to vapor.
“this table” from post #1
was caused by the chemicals used to clean up the residue after an electrical fire.
This chunk of (mostly) copper was later found underneath the suspected arc fault
and is the largest contiguous chunk of copper found. The central comb-looking thing is an asbestos arc-flash divider from inside a large 3-phase circuit breaker, and the brighter splashes near it is silver that melted from the breaker contacts. The phenolic from the breaker housing and the steel from the buss duct were turned to vapor.
FredWanaker
Well-known member
Steel has a Mohs hardness of 4.0. Black rust has a Mohs hardness of 5.5. Titanium has a hardness of 6. Cobalt 5. Black rust forms when red rust is denied Oxygen and has low moisture, like when it is hot and oil is put on it. A black cast iron pan is just as shiny as regular steel and rusts the same red until it is heated and oiled. The sap from the tree may have covered the red rust and denied it O2, or the fire you reference may have been the culprit.
Chance
Well-known member
I did not know black rust was harder than cobalt. Cool! Thanks!
Renegade1LI
Well-known member
Try using a floor sander, start with 60 grit & go up or down as necessary. I've sanded some sheets of road plate & finished with 120 & they looked great.