Pot metal - die cast metal repair

[bernardi]

Here is a vendor I came across on a Jeepster thread. Someone had pitted headlight rims and asked for help in correcting them. A fellow poster suggested Muggy Weld (I never heard of it, either). On general principles you probably want to visit this site. For one rod they claim a melting point of 350 F. There are others with different characteristics. They aren't really cheap unless you consider the alternatives. It seems to take chrome nicely, if copper and nickel

plated first.

http://www.muggyweld.com/

I hope it lives up to the claims - There are a lot of things on my 400 that would benefit from it.

Can someone tell me how to remove chrome from pot metal?

[mrpushbutton]

The only way I know of is to send the piece(s) to a plater, who will dip them in a cyanide tank (very unplesant work, that)which will strip the chrome, nickel and copper layers off. I would recommend you buy a piece of good used chrome that isn't as pitted and work from that. In the end you uwill have a better piece that takes less time to work and is less likely to pop on you after being plated. Plating is a blind date!

[Restorer32]

Save yourself a lot of aggravation and just send your pitted potmetal parts to a reputable plater. There is one thing that is always missing from those packs of "miracle" welding rods and that thing is experience. Next time you are at Carlisle or anywhere where there is a guy selling these products, ask him how much experience he has welding. Likely he has been welding/brazing/soldering for many years. We used to have spaces at Carlisle next to a guy selling similar miracle rods. He could weld aluminum beer cans slick as anything. Turns out the rods were the same as you could buy at any welding supply shop. It was his 26 years as a welding teacher that allowed him to make them work. You will notice that these demonstrators will weld old heavy die cast and they will weld thin new aluminum but you never see them weld old thin diecast or old thin aluminum. I suggest you try repairing at least one of your die cast pieces yourself. You will gain a greater appreciation for what platers go thru to earn a buck. Most platers would strip your potmetal, copper plate and then make repairs with common lead-tin solder before copper plating again to encapsulate the repairs before nickle and chrome plating.

[Guest Randy Berger]

Good advice from knowledgeable people. I had all my pot-metal done at Potmetal Restoration in Tallahassee, Fla. The small chrome piece on my gas tank door could have been used as a rasp - it was that bad. I got the piece back and it was gorgeous. I think he is the only one doing potmetal in the fashion he does. He does not grind away the pits until the part disappears. I'm not 100% sure of his exact method, but he does do great work.

[R W Burgess]

Randy, I sit here reading all of these comments about the chroming craft. I, to, have had some excellent work done in the past. It depresses me to think that the talent may be lost as there are few young people willing to take up the trade. Hopefully, local trade schools will hook up with these excellent tradesmen to keep the business going.

Wayne

[Guest bkazmer]

If I remember correctly,the cyanide bath is to get better adhesion of the plating (cyanide is a chelating agent.

[jrbartlett]

It's my understanding that old plating is stripped off by reversing the electrical flow that would normally be used during new plating. Is this correct?

[mrpushbutton]

I've always understood that it is the cyanide that strips the old work as wellas prepare the new. I drop my pieces off, they strip them, I take them back and glass bead them (to my satisfaction) and then I bring them back for copper-building. Then the fun begins.

So I can't say for sure what the process is, I don't go in the back.

[Guest sregenauer]

ok first it elec. dipped to strip then balsted all dark grey must go even if it makes a hole then the fun begines grind all small pits out then flash copper 2 min. then solder dont meld it then gring then copper as needed and repeat i do it all day scott

[Coley]

The Florida shop uses the old "baby shoe bronzing" system from the 1940s/50s.

He repairs the part by stripping the chrome and then using body filler, firbreglass amd other products to fill all the imperfections.

Then he coats it with a conductive spray coat and plates as usual.

It is the same process that you see at flea markets where they have gold plated leaves etc.

I had a 1957 Chevy taillight housing done and it was very good looking. Just wasn't sure how it would hold up to weather.

A friend of mine just bought a "Plating" system that will chrome PVC pipe if you want.

It is called Spectra Chrome. Water based and friendly to the enviro.

Edited January 4, 2012 by Coley (see edit history)

[Owen_Dyneto]

The process for "plating on plastics" is a well-known commercial process and used extensively in industries such as the printed circuit board industry where it is used to metallize (with copper or occasionally nickel) the drilled holes thru the fiberglass board to connect circuitry from one side to the other. I spent a lot of years in this industry - in it's commercial form it's a complex multi-step (about 16) process. In a nutshell, the copper salt is chelated and in an alkaline media also containing formaldehyde as the reducing agent. There is a precious metal catalyst, usually palladium, which at the surface triggers the chemical reduction of the ionic copper salt to copper metal at the surface.

There are more modern iterations of the process that use carbon black or graphite on the surface of the plastic to produce a conductive layer which can then be plated. Both methods have large-scale industrial application, not only to "electroless" plating for PC boards, but also for decorative and RFI plating on plastics.

[Guest Albert]

there is a product out there that you mix like JB weld, but is electricly conductive and will plate like regular steel

[barryh]

In my experience, the best process for repairing damaged or pitted diecast parts is to strip, bead blast, lightly grind/polish, and cyanide copper plate the item to begin with. In my opinion, it is a waste to attempt to grind imperfections off- it will only ruin the part. I only remove the bad metal, nothing else. After a good coat of copper is applied, all imperfections can be built up or filled w/ silver solder (more expensive & time consuming than plastic fillers, but it will last.) The solder is then carefully filed down and polished with close attention being paid to the shape and details of the piece and afterwards a second coat of copper is applied. Too much copper will cause failure of the finish and is a waste of expensive material. Too thin of a copper base risks a lower quality final finish & invites early failure because of insufficient barrier between the pot metal & the nickel. After 2nd coat of copper, item is polished, inspected, and only if no imperfections can be found will it be placed into the nickel tank, followed by a quick dip in chromium for a gleaming shine that will last for decades. I have been in the plating biz for many years with most of my customers being in other states or countries, so I can not afford for items to be returned for plating failure. It pays to do it right the first time!

for info on high quality plating see www.studebakersite.com

Edited January 7, 2012 by txrebel (see edit history)