Case annealing machine

[Popsbengo]

I've dug out my heat treatment text books and read up on salt bath furnaces. I'd like to share some advice therein:

Potassium Nitrate and Sodium Nitrite mixture is a commonly used product for heat treatment, mainly the tempering of steel; especially complex items with differing sections. The process is relatively safe as long as sensible precautions are taken.

When melting go slow and allow the salts to settle for a while to drive off any absorbed moisture.

Do not allow any water or oil near hot salts, this is dangerous.

Molten salts are relatively safe up to 500 deg Celsius but DO NOT heat above 550 deg Celsius because it becomes highly reactive and oxides of nitrogen form which can cause severe breathing difficulties. Therefore it's recommended to have accurate temperature measurement and don't ever leave the pot alone when switched on. Good ventilation is recommended.

Do not handle cold salts with bare skin, if contaminated wash off with plenty of cold water. If HOT salts splash, flood the burn with cold water and possibly Sodium Bicarbonate solution (I have some made up) - see a doctor as the burn could be deep and serious.

Any salt contaminated fabric, wood etc should be disposed of carefully as the salt solution will vigorously promote combustion.

Keep salts away from children as they are sweet to the taste and sodium nitrite is quite deadly in amounts of a few grams if ingested.

Apart from that it's not any bigger risk than many worksop activities (lead smelting for one). One thing that's occurred to me with regard to brass case annealing is to ensure the cases are de-capped or rapidly expanding air may splash hot salts.