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Hot dip tinning vs. tin electroplating

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Q. I am looking for a home process to tin plate reproduction spurs. Originals were cast malleable iron and tin plated, they date to the early 1800's.

John Vaccaro
- Dillon, Montana


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A. Hi John. Around here we're not big on doing metal finishing at home.

But please look into some of the books listed at www.finishing.com/books/ for an introduction to the subject. Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


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A. Hot dip tin is NOT plating. There is no electrical or chemical activity. Hot dip amounts to having something that can get tin to its melting point, dipping the part in the molten tin and then trying to get the excess off. We used to refer to it as the dip and sling method because if you tossed it into the corner of a cardboard box so that it would caroom off at least two sides, it would not have too much excess tin on it. Allowing the part to stay in the tin longer gave a little higher part temp which gave a little longer "sling" time.

A small amount of lead will lower the melting point a fair amount. I would not take it to the eutectic point of 60/40 tho.

Tin is reflowed in very hot lard. Now that is a stinky mess.

James Watts
- Navarre, Florida


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thumbsup2Thanks, Jim, I wasn't alert to the fact that we were talking about hot-dipping. Whether hot dipped or electroplated, tin itself is usually not regulated in the effluent. So it's then a matter of whether cleaning and pretreating is a safety or environmental issue, and avoiding post treatments.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


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A. Ted, I am going to mention this just for fun. But tin plating on copper and brass utensils at home is still a big "small business" in the third world. Once every couple of years, these proprietors used to come to our door to check if tin plating was needed. If so, he would set up his tiny operation in our yard. A charcoal stove to heat the pot, a white powder to rub the hot pot using cotton glove as the preclean, and a tin wire. Once the surface was cleaned, he would rub a little tin wire on the hot surface and then polish the whole surface with the same cotton glove. I forget the name of the white compound but that compound generated a lot of white vapors which I am sure are toxic. But the guys lived for many years for sure. You would not believe how bright and shiny the pots looked.

Mandar Sunthankar
- Fort Collins, Colorado



thumbsup2Thanks, Mandar. An update for the readers: This site now has a number of threads about the tinning of pots as mentioned by Mandar. Please see letters 25553 and 29192 for starters or search the site for 'tinning copper pot'.

Remember that only lead-free tin, not solder, must be used on a vessel for food or drink.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



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Q. Can you give me some suggestions on hot dip coating tin on Aluminum?

Dingmin
sjtu - Shanghai, China



A. Hi, Dingmin. The only way that I am personally aware of doing it is to zincate and then copper electroplate the aluminum before the tinning.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



thrashing

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Q. Would like to know: what are the main components in a tin plating line.

Marc P deleted
- Houston, Texas, USA


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A. A hot dip tinning line may contain many of the same process tanks that an electrolytic tinning line does, Marc: alkaline cleaning, acid activation, and post treatment dips in anti-tarnish treatments, plus rinses between each step. But in place of the electroplating tank it has a flux tank and a tin dipping tank.

If it's a continuous line, such as for wire, it probably has "wipes" of some sort to smooth out the tin and remove the excess. Good luck with it.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



May 8, 2009

Q. Is "Hot Tin plate" different than Hot Tin Dip?

Casey Heitzman
metal finisher, Oregon


May 2009

A. Hi, Casey. Unfortunately, people invent ambiguous slang constantly so there is no saying what they might be thinking when they decided to call it "hot tin plate". But I personally do not know of any other deposition processes that might be called "hot tin plate" other than "hot dipped tin".

Good luck.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


July 19, 2009

Q. I am working as production engineer in a plant producing cables and plugs for home appliances. On one side of the cable we attach plugs and on the other receptacles with brass materials. We would like to work on tin plating which is very common for both receptacles and plug connections.

Cumhur Esin
Production engineer - Istanbul, Turkey



October 15, 2012

Q. We have a unit here for hot-dip tinning on copper wire, but nowadays customers are asking for Tin plated instead of hot-dip. Please suggest which process is more suitable for copper wire which will be used to make cables.

Thanks
Kannadas

Kannadas Attupurath
wires & cables - Daman, India


First of two simultaneous responses -- October 17, 2012

A. Electroplating is preferred to hot dip tinning when a thinner, pore-free coating or a more uniform thickness is desired.

Also, in the hot dipping process, a brittle copper-tin intermetallic compound is formed at the interface. This is minimized or eliminated by the electroplating process.

Lyle Kirman

Lyle Kirman
water treatment systems - Cleveland, Ohio

Second of two simultaneous responses -- October 17, 2012

A. Hot dipping will give you a much thicker coating than electroplated tin, so it depends from what perspective you are looking. As a customer, I would like hot dipped, as there will be better protection, but from the producers side, hot dipping will cost more in tin. However, hot dipping is easier to do and hence cheaper (I presume you do not have either hot dipping or plating facilities). If you decide to reduce your tin costs and go for electroplating, you have to factor in the costs of a plating line, chemicals and pretreatments.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK

October 22, 2012

A. Both hot-dip and electroplating are suitable, and either will work in all uses of tinned copper wire.

The equipment for electroplating is more expensive than for hot dipping. It also usually runs just one wire at a time, whereas hot dipping can have dozens of wires in parallel. Electroplating is only practical for coating large wire sizes, while hot-dip is better for smaller diameters.

Thickness control is better with electroplating, but thickness can be controlled quite well with suitable wipes in hot-dipping.

Hot-dip has lower equipment costs, higher production speeds, and fewer problems. I would use electroplate only for large sizes (> .015" or thereabouts).

jeffrey holmes Jeffrey Holmes, CEF
- Spartanburg, South Carolina
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