Tin plating

advice.

I think it is no more than getting them ABSOLUTELY clean and hot dipping in molten tin. Certainly this is how bearing caps are done. The problem is the cleaning to chemically clean bare metal - possibly you could sand blast them ?

AWEM

Thanks AWEM Would have to be chem clean as they have a small rolled edge that would be difficult to blast clean in the crevice where it meets the mould side. I have tried cleaning in a strong caustic solution and achieved visible removal of carbon, grease etc. Is that sufficient?

No flux? Would the item be dipped cold, or preheated? As it is for food contact, does it require pure tin?

Appreciate your help.

Cheers Spurtle

Small areas can be physically cleaned and repaired with a soldering iron, with all trace of lead removed of course. Finding a source of tin is the problem here. Regular acid flux [ZnCl] works fine. Bugs

done.

possibly

achieved

Your problem is keeping the items clean between blasting / acid dip / caustic dip or whatever and the tin dipping, as probably they won't be done either in the same room or the same time ! Fry's make (made? - long ago since I used it!) a tinning flux that if sprayed onto the cleaned metal would keep it clean.

If you have rolled joins that can trap moisture, you have another problem when dipping - the moisture will form steam explosively when dipped and splash tin everywhere.

As to the purity of the tin I don't know, but tin tends to be associated in nature with lead and arsenic so I assume that their percentages should be microscopic for your application !

AWEM

You might want to try the old way.

've tried to do it this way once using nontoxic pewter and my results were good in some places and not so good in others. It certainly seems like something that could be learned with some practice. I don't remember but I probably used a wadded paper towel as the swab. I seem to remember the paper towel browned and smoked but didn't ignite. I think my main problem was insufficient prep in the cleaning. I used a torch. I think charcoal would be better for more even heat or maybe a gas stove top. Karl

Karl

You can send it off to a professional tinker or do it yourself.

The professional way is to use bar tin and flux over a hearth of crushed firebrick but there is an easier way that works almost as well. You can get most of the material from a stained glass supplier. Just make sure the solder is pure tin.

I used Johnson's E-127 Flux N Solder pure tin to retin some copper pots. It is a paste of flux and pure tin powder. Clean the pan well and make sure it is free of grease. Sand off any rust. I used some fresh carburator cleaner and then rensed off thoroughly. Coat anything that you don't want the tin to get on with whiting chalk and set it aside to dry. Brush the paste on thinly and evenly then heat the pan with a propane torch (preferably from the outside) until the solder melts. About 450F. Don't over heat and keep the torch moving to prevent hot spots.

A much better way to do it if you have a propane fish cooker is to set a larger pan full of 1/4" chunks of crushed fire brick on the cooker and set the pan to be retinned down into the bed of crushed brick. It will heat a lot more evenly. Don't use fine stuff because if any gets into the tin it is impossible to get it out.

Once the tin is all melted swish it around to make sure all the metal is coated and pour out the excess. Quickly, while still molten, wipe the pan with a thick piece of wool to level the tin.

Steel is a little harder to heat evenly than copper but a steel pie tin will be easier to do than a copper pot because you don't have to worrry about getting the tin on the outside copper.

The Johnson E-127 is probably the paste you are thinking about. It is a mixture of tin and flux. Johnson also sells tinning flux for steel and bar tin but that takes a lot of practice and a real tinning forge to maintain even heat.

96% tin - 4% silver solder is made by several suppliers. Harris Allstate, and Brownells are some of them.. It melts at 475° F.

Randy

Well, unless the paranoids have taken it out of circulation, there is liquid tinning stuff sold in electronics shops (got mine a future/active a few years ago). Dip Copper, brush on, etc. NOW, it may not like the base metal enough to plate out. Sn is more active than Cu, but if the pan is Iron, forget it. /mark

Spurtle wrote:

When I was in France last year, I watched coppersmiths tinning cooking pots with zinc chloride flux and bar tin. They made it look easy (of course they were pro's) and were doing it over a plain gas ring. Clean the pan, flux the part you are tinning, resist the rest (they used a chalk wash), then heat over the gas flame while rubbing with the bar tin. When it starts to deposit, run it all over the pan, then take a heavy cloth and wipe it around evenly. All done. Didn't take more than a couple minutes per pan.

I suspect the end result improves dramatically with practice! :-) These guys probably tin thousands of pots a year.

Regards,

Bob

Many thanks to all for the tips.

Project defered while I deal with an unpleasant crisis.

Cheers.