Topic: de chroming

[dave500]

has anyone done any "de-chroming"at home on small parts,ive had stuff done before at shops and its quite expensive,i know people can chrome at home,ide like to de chrome a few parts at home if i can ,what voltages/amps and liquids are used?any tips?

[BobbyR]

Probably you can chemically disolve it with acids. Do a search on what not to put on Chrome and that is your answer.

[mick7504]

Dave
I think that there's some pretty nasty chemicals required to get that shiny stuff off.
Mick

[gmonkey]

Any advantage to that over just sanding it off besides not having to spend all the time sanding?  Chrome harder than the metal underneath so you take off too much material wherever you break through the chrome first?

[mystic_1]

Dave
I think that there's some pretty nasty chemicals required to get that shiny stuff off.
Mick

Yes, and the byproducts of the process are quite toxic as well, both the fumes and the residues.  Not recommended for home hobbiest.

Ever heard of Erin Brockovich?

mystic_1

[nokrome]

ive de-chromed parts by bead blasting, it leaves a slightly textured surface that is good if you want to paint them afterwards

[BobbyR]

Try a small sample piece in 100% Simple Green. Model builders use the stuff to dechrome parts.

[dave500]

yeah ill google around,i think nasties are used to put chrome on but its just a mild acid bath with reverse polarity to remove it.

[mystic_1]

From:  http://www.nmfrc.org/crarchive/jan02a.cfm

The facility electrostrips hard chromium plating from steel parts, for its refurbishment, according to MIL-STD-871, solution #6 (68 to 82 grams sodium hydroxide per liter of water, at 6 volts anodic, and room temperature - 60 - 90 degrees F). This process (also known as reverse current stripping, as well as anodic stripping) oxidizes the metallic chrome plating to hexavalent chromium. The process requires either part or bath agitation so that the chemicals are mixed at the part surface. These chemicals transport the hexavalent chromium from the surface of the part and into the bulk fluid. The hydroxide anion complexes the chromate from the part surface, and dissolves it into the solution as sodium chromate (Na2CrO4), which gives the solution a distinctive yellow color. Although the exact mechanism of this reaction could not be found in the literature, the following pathway is possible, leading to the final products:

Cathode Reaction: 6H2O + 6e- = 6OH- + 3H2(g)
Anode Reaction: Cr(s) = Cr+6 + 6e-
Hydroxide Reaction: Cr+6 + 8OH- + 2Na+ = Na2CrO4(aq.) + 4H2O
Overall: Cr(s) + 2H2O + 2NaOH(aq.) = Na2CrO4(aq.) + 3H2(g)

Reverse plating chrome in a sodium hydroxide solution produces, in part, hexavalent chromium.  Not something to mess around with.

mystic_1

[Retro Rocket]

Dave,i don't know for sure but someone told me that oven cleaner strips chrome off, don't know this for certain but if you have a chroming place  near just give them a call and ask...

Mick

[dave500]

thanks fellas,yeah mick ive had de chroming done at custom chrome nerang,they dont have an eftpos machine because they only last a few months there in the atmosphere!!the bank refused to give them anymore.40 bucks to get a set of 4-1 headers done and 20 for a hand full of small parts.i think ill pass on the home poisoning effort.we used to once every couple of years supply them a couple of skips and some company de sludges the tanks and corrects the ph and what not in the dirt like stuff that comes out and then its epa certified and we take it to a special land fill,we had a pair of full bins sitting at a yard for a few weeks and all this green copper sulphate looking puss leach all around them,those bins were then forever really rusty.

[cookindaddy]

I've taken parts to my neighborhood sand blaster and they come back cleaned of chrome with a slightly rough finish that as nokrome said, are great for holding paint. If there is pitting in the chrome, the underlying steel is pitted and this will show in the texture after sandblasting.

[dave500]

thanks cookindaddy,i took these pipes to a sand blaster who does work for my boss and he suggested getting them de chromed as sand will just more or less bounce off,chrome is hard,if you want re chrome then de chrome is the go,chrome like painting requires a good flat surface to start with,sand blasting is bad for a chrome refinish,steel must be polished before plating,you cant just chrome over defects,they will show up.

[traveler]

die grinder

[Jerry Rxman Griffin aka MuthaF'er]

Caswell.com I believe has a nice home chroming kit and also mentions removing chrome?