Heat Treating Plates
The heat treating is done
by heating the plates to 1575F/857C and quenching them in hot water at
around 120F/49C to 150F/66C. If the water isn't hot some of the plates
crack between the plate edge and holes near the edge. This only seems
happen with small thin plates with lots of holes in them. After
quenching the plates I temper them to 650F/343C for 30 minutes. The
temper is just soft enough so that you can still reshape the plates a
bit if you need to and soft enough so that they won't tend to crack due
to all the holes in them.
After heat treating the
plates I use coarse 3M Scotch Brite surface conditioning discs on an
angle grinder to thoroughly clean the plates. Even the edges of the
plates need to be cleaned. I found that mechanically cleaning the
worked far better then cleaning them with acid.
For tinning the plates I have a electric melting pot that I built using soft fire bricks and heating elements. A stainless steel pan 2 inches deep by 13 inches square fits into inside of a shallow box make of fire bricks with heating elements embedded in the bricks in the bottom. There is about 1.5 inches of air space between the bottom of the pan holding the tin and the heating elements. The air space allows the bottom of the pan to be heated evenly. A computerized temperature controller heats the tin to a preset temperature and holds it at that temperature by cycling the of the elements on and off.
I seem to get the best results by heating the tin to 650F/ 343C, the tin is hot enough to give you some working time to shake off the excess but solidifies reasonably quickly. Before submerging the plates in the tin they need to be brushed with a liquid soldering/tinning flux. By far I have had the best results with "Nokorode Fluid Flux for Soldering" from M.W.Dunton Co. and "Stay Clean Liquid Soldering & Tinning Flux" from J.W. Harris Co., Inc.. The liquid fluxes seem to work much better then paste fluxes and the liquid flux doesn't left nearly as much residue as a paste flux. I use steel wire to suspend the plate from while submerging them in the tin. Be sure to shake off as much excess tin as possible after you take the plate out of the tin. Wear a clear face shield when you do this! After dipping the plate in the tin you can use a cheap disposable brush with flux on it to brush the excess tin off of the plate. You need to do this quickly before the tin solidifies. This will give you a much more even coating of tin and helps to fill in any spots where the tin didn't initially stick to the plate. Also you do need good ventilation in the room to get rid of the fumes from the burning flux.
If you want a harder temper you can temper and tin the plates at 600F/316C but the working time to shake off or brush the plates with flux will be very short (5 to 10 seconds). Also with a 600F/316C temper you will be much more limited in how much reshaping can be done after heat treating the plates.
After tinning some pieces of
riveted maille I feel that tinning larger maille items should be
possible. The item should first be cleaned to a bright finish by
it in a tumbler with an abrasive media. Then dip the item in a liquid
tinning flux before submerging it in molten tin heated to 650F. After
pulling the maille item out of the molten tin it needs to be shaken for
about 15 seconds while the tin solidifies so that the rings don't end
up soldered together. Droplets of molten tin will be coming off of the
maille while your doing this so protective clothing and a face shield
need to be used. There will be a rough finish on the mail because the
tin was being shaken at the time it solidified. If you put the maille
item in a cloth bag and shake it around vigorously for a few minutes it
should removed a fair amount of the roughness in the finish.
How to Make an Electric Tinning Pot
Where to Buy Tin and Electric Tin Melting Pots
Ney Metals (Tin ingots
and tinning flux)
McMaster-Carr (Electric Tinning Pots. Search for "Melting Pots" and look for sub-category "Rectangular High-Heat Melting Tank")
Commercial Tinning (tin hot dipping)
Company They can tin a 340 quart mixing bowl so I would think
that breast plates, back plates, and helmets should be no problem.
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Copyright 2006 Craig W. Nadler All rights reserved