DIY Hand Wiped Tinning of Old Copper Pots/Pans

http://www.instructables.com/id/DIY-Hand-Wiped-Tinning-of-Old-Copper-PotsPans-Inst/?ALLSTEPS

Step 1: Gather your supplies!

Things you'll need:

• Distilled white vinegar (the cheap kind for cleaning)
• A non-scratch sponge (for the outside of the pot)
• Fine steel wool/Brillo pad (to clean up the old tinned inside of the pot)
• Bar Keepers Friend (also amazing for cleaning stainless steel, old rusted bits, or other metals)
• muriatic acid (also called hydrochloric acid)
• flux
  • I used sal ammoniac/ammonium chloride
  • Ruby Fluid is the other alternative
• a heat source
  • plumbers torch (brazing torch)
    • use gas & blown air, or a big petrol / paraffin blowlamp.
    • Don't use an oxy-acetylene as it burns too hot. You need low/medium disbursed heat.
  • propane turkey fryer
  • I've even heard that a bunsen burner will work
• pure tin
  • I got mine at rotometals
  • 1 lb is more than enough to do over a dozen pots/pans
  • Only use pure tin (or 99.99% pure tin). Don't use tin based solder, which has lead or antimony in in
• plumbers wad/wiping cloth
  • Traditionally made using a thick type of cotton cloth called moleskin (think the stuff they made construction work suits out of)
  • I used some old jeans, cut up palm sized sections, then sewed three or four layers tightly together and soaked with warm tallow
• respirator mask (safety first!)
• safety glasses/google (protect those eyeballs!)
• heavy work gloves (suede leather is probably best)

Step 2: Clean it up, inside and out!

The pots I got had a great patina on them, but I'm planning on cooking with them for decades to come, so I started by soaking the pots in a hot solution of water/vinegar. After half an hour or so much of the years of grime/neglect came right off and they started looking bright and shiny. Then some Bar Keepers Friend and a sponge did the rest. They looked great on the outside, but still some grunge/verdigris/dull tin on the inside. Next step was a brillo pad on the inside. I scrubbed until there was no more verdigris (green copper oxide) to be seen). Lots of copper showing through and overall very clean.

Step 3: Pickle (degrease) that pot, in acid!

Next up was a soak in an acid pickle to degrease the pan, and get it spotless. Always use a plastic container, a 5 gallon paint bucket with a lid works great. First fill the bucket with water (I used three gallons of water), followed by a bottle of muriatic acid (you can get this at a hardware store, I used a full gallon). 

• PRO TIP, ALWAYS pour the acid into the water ! NEVER NEVER add water to the acid ! (tip of the hat to Jake on that one).

CAREFUL, this is acid so even if it is diluted it is still nasty stuff, so use gloves and protect your eyes from any splashing when you dip the pot in or take it out. Always be near a water source in case you do splash yourself and need to rinse off.

The acid will eat away any left over carbon build up, grease, and will soften/eat away at the dull tin that is left on the inside of the pot.

After an hour I took out the pot and gave them a good rinse, the muriatic acid will change the color of the copper to a light pink (unless there is lots of patina and gunk still stuck on there, which sometimes discolors it a bit).

Once the outside has been cleansed of acid, I gave mine a final Brillo scrub on the inside to get and loose bits, it some places it gets down to the bare copper, which is fine.

One more rinse and now it was ready to get a fresh coat of tin!

Step 4: Tin that pot!

First, I sprinkled some powdered sal ammoniac (ammonium chloride) on the inside of the clean pot (if you have a different flux coat the inside of the pan).

To avoid getting tin on the outside of your pot you can put "whiting" on there (powdered chalk with a little water works I'm told). I personally skipped this step and didn't have too many problems with dripping tin on the outside.

• PRO TIP - To get the tin flowing over a wide area more easily you can also pre-heat your copper pot in an over at 450. If you choose to do this I wouldn't apply flux until the next step when you are out of doors. I've done this with a pre-heat and without, both turned out fine.

Safety first ya'll, definitely be sure to have a long sleeve shirt, long pants, and closed toed shoes on. The pan will be really hot, as will the tin and you don't want it touching your bare skin. HAVE A RESPIRATOR, EYE PROTECTION AND LEATHER GLOVES. The sal ammoniac will create a thick white smoke when heated, and from what I hear it will rust anything it touches. Also, not good to breath in since it is corrosive, so use a good respirator mask.

Bring your fluxed pot outside (DO NOT DO THIS INSIDE ON YOUR STOVE). I used a propane turkey fryer as a heat source on a medium heat. Put your copper pot on there and slowly heat it.

• PRO TIP - Since copper both gains and loses heat quickly you can create a basic brazing hearth using fire bricks. Just lay them our around the flame of your propane burner, google around and you'll get the idea.

The sal ammoniac (ammonium chloride) acts as a flux so that the tin will stick to the inside of the pot. Once the white smoke starts billowing throw in a small piece of tin, or rub some tin bar around the bottom of the pot. If the pot is hot enough (456 degrees or so) the tin will melt right on there. Swirl the molten tin around, sprinkle a little more sal ammoniac in there (clouds of smoke!), then rub the molten tin around with your plumbers wad (be sure you have gloves on). You can also use tongs to hold the plumbers wad/wiping cloth you you don't have to get your hands anywhere near the hot pan, probably not a bad idea.

You may have to heat the sides of the pan separately to get the copper hot enough for the tin to bond there. Where the handle meets the pot will also require additional heat (as the handle acts as a heat sink).

Trial and error will play a part. As you are heating you will see when the old tin melts, as it starts to get shiny and change color where the heat is applied. Know that you can always cool the pan down and remelt the tin, you'll get many shots at getting it right.

You can let the pan cool down naturally, or use the assistance of a 5 gallon bucket of water. Be careful not to dunk the hot copper into cold water immediately, as this could warp your pot/pan. I generally scooped up a little water, rolled it around the inside of the pan, and then scooped up some more to slowly cool the pot before fully submerging it.

Step 5: Try, try again

My results were mixed my first time around, but the inside of the pot ended up fully coated in tin (except for a few little spots on the upper edge, visible in this picture).

I used way too much tin the first time, so it isn't smooth, but it's ready to cook in now! I got better with a little trial and error over time. I had to move the pot around, and heat the sides to get the tin flowing.

Also, a little heat goes a long way, so don't use too much heat or you'll end up burning your plumbers wad/wiping cloth and then burned bits may keep some areas from bonding. A plumbers torch would have been handy for more accurate heating (there's always a next time).

Worst case scenario you just start at the beginning and do it all over again. In fact, on a few pots I did the bottom very successfully, but the sides not as well. I just went back and scrubbed, pickled, and rinsed before going back to do the sides a second time.

For someone without any experience other than googling for a couple hours, I have to say it was a lot easier than people made it out to be on the internet. Use caution (gloves, long shirt/pants, respirator) and you'll be fine.