Anyone here built or planning to build salt tanks?

I'd like to get a high-temp tank and possibly a low-temp for mar-quenching / tempering built this Summer. I am planning to make the big move to sword-length pieces...

I have the basic concept down but would love a primer on solenoid controllers and a few other technical issues.

I really can't see as how they're necessary. I run a 4" X 40" stainless tube and use it for swords, and a smaller black iron tube for knives. I use a pyrometer and tweak the needle valve to get the salts where I want them, and it's not hard to hold/jump/drop the temp 25 degrees within a couple of minutes. The solenoid would be nice so that you don't overheat the salts while they're warming up, but if you check the pot occasionally over the half hour it takes to warm up, it's hard to overshoot. Are you going to be soaking at high temps for extended periods of times? if not, I'd do without the wiring on the high-temp pot.

If you're using water for a quench, remember WATER BAD NEAR MOLTEN SALT and get that blade dry before it hits the low temp salts. Also, do a preheat of your blades to drive off moisture before going into the high temp salt or else you'll be wearing it. And cover the tube with a piece of plate while i'ts warming up because they like to spit. Salt pots are very dangerous rigs, but I wouldn't trade mine for any other method, they're GREAT for swords, especially with the japanese style water quench.

Hey Joe,

I suppose you could go manual - just like my forge with a thermocouple in it... hadn't thought of it since the discussions on the subject I've always seen mentioned controllers.

Some of the basic questions I have are thus:

Is there a special consideration on welding the bottom onto the salt-tube? Seeing as how the running temp is going to be 1500 or so I just wanted to make certain.

You have a 4 x 40 tube - what is the diameter of the surrounding cylinder including the insulation and the actual airspace where the gas heat flows? ( a cross sectional explanation would work great... )

What is the thickness of the 4 x 40 tube?

Do you measure the temp of the heating chamber as well as the actual salts? In the sword length tank do you measure the bottom of the tank temp as well as the top?

Thanks in advance...

then rebuilt it so it'd run right. Here's my opinions:

1. welding on the bottom: Weld that sucker on water tight and don't cheat. no pin holes, no nothing, and use the same material as the tube is made out of so it doesn't shrink/crack on cool down.

2. I've got 1" koawool lining a 14" chamber. You should have about 3" around your tube or else you're going to get hotspots. Even heating of the chamber= even heating of the salts. I have 2 burner ports, one at the very base of the pot and one in the middle. when I'm in a hurry i can melt the salts within 20 minutes, but you only need the one burner as long as it heats the entire chamber evenly.

Make sure the burner heats the bottom of the tube or else the tips of your swords won't get hot enough (good idea to suspend them a couple inches with a wire--a thick wire, i still have to fish out a poinard one of these days).

3. Get your tube as thick as possible, mine's 3/8" 304 SS, but it really should be 416 for durability. expensive stuff, but don't be cheap, cause that runny molten salt doesn't think much about the soles of your shoes, and when it hits wet cement excitement is all around the place.

4. The bottom, middle, and top of the tube will give you precise indications of temp throughout your salts, and if you're doing real precision stuff, i'd recommend that. You only need to measure the temp of the salts, not the inside chamber. I use one thermocouple, about 3" into the salt, and check for even color throughout the blade visually. Real easy to do and you can spot differences in temp of 25 degrees.

make sure that the insulation that caps the chamber(the lid) is about where your salt level should be. My first salt pot had about 3" of tube protruding, and that 3" was about 100 degrees colder than what was under it.


What kinds of swords are you making? If you're doing to be doing japanese style stuff, I've got some good heat treating tricks if you're interested.

here's a good site about saltpots.

www.mstarling.com/The_Cra..._pics.html (http://www.mstarling.com/The_Craft/Tool_Plans/Salt_Pots/Salt_Pot_Pics/salt_pot_pics.html)

note the part where he says that the salts can be made from calcium chloride (used to melt ice on roads in the winter) and NaCl (regular table salt). You can get a bag of calcium chloride dihydrate (bit of water in there) for about 25 bucks from www.mcmaster.com, and table salt is real cheap. I haven't tried making any salts yet, but this could save you some money, and I wish i'd known about it before i ordered mine.

Good luck, wear long gloves, goggles, a face shield,a hat, and a heavy apron.

Joe,

That site and your advice is exactly the thing I was looking for - much thanks... pics make all the difference. I was entirely sold on the salts at the Ashokan Blade Conference last year when I heard Tim Zowada and Kevin Cashen discussing the matter... just bring it up to a polish and go? Right on! I've paid my dues and learned a lot treating in the forge... but quite ready to move along.

I'll be interested in the differential heat treating in a few years, no doubt, but for now I have to pursue my immediate passion: I'm planning to start up on the Migration Era / Viking Age composite pattern welded swords mostly - I've done a few daggers in the style - the most complex was a four-core twist and split with a high carbon edge and I sold it before I started taking pics of every knife that leaves my care... :-(

So it looks like I'll be putting together the salts in the next few weeks - may I presume to e-mail you with any questions? Thanks again for the advice - and anyone else out there who knows anything else about it - I could use any input I can get!

I'll never go back to heat treating swords in a forge, with the exception of a long bed pine charcoal fire pit.

I'm planning a small square salt pot for brazing habaki soon--bring the habaki up to temp and give the joint a gentle squeeze and presto, no scale no nothin'

I'm a fan of norse pattern welding, but haven't done any damascus, other than wire. Don Fogg has done some pretty amazing celtic work too, and that appeals to me. Never let it leave the shop without getting a couple pictures first (i'm putting together my website and found out I screwed up by not getting enough pics of my work, live and learn i suppose).

Any questions with the salts or anything else, just email me at: moonlitforge@home.com