Heat Treat Foil (Tool Wrap) 309 - up to 2240F - Full rolls
Stainless Heat Treating Foil
- type 309 Stainless
- commonly called Tool Wrap
- .002" thick
- most rolls are 20" wide
- Use 309 for heat treating temps up to 2240F degrees
- All-Foils quality Stainless Steel
Use this higher temperature rated 309 tool wrap for steels that require more than 1900F for heat treat. If you are heat treating to a temperature less than 1900F the 309 wrap will still work fine, but the 321 (lower temp) is a bit cheaper.
Tips: Wrap your knife one or two (at most) at a time making an airtight envelope. Fold over the seam twice and tap the seam closed with a hammer. The seam is to the side, not on 'top' of the blade - this matters later. I try to wear leather gloves any time I handle this stuff. The edges on this are razor sharp. You will believe me when you cut yourself. It's just a matter of time. Handle it with respect.
Some guys put a piece of paper inside the envelope to burn up the oxygen so the blade steel does not carborize. I don't see much advantage to this. Just wrap it tight and there won't be any oxygen to speak of. Ideally, the envelope will tighten around the blade making solid contact.
If you plate quench, simply leave it in the envelope and quench it inside the tool wrap. If you oil quench, you need to wrap it a little looser so you can snip the foil pouch open and dunk the blade quickly.
Plate Quenching: Get scrap aluminum plates at least 1" thick. Make it a couple inches longer and at least 4" wider than your knives. When it comes time to quench, move quickly and put the (scary, hotter than hell!) foil pouch with blade blank in between the plates and press. Some guys use a wood vise with plates installed. I just press with my hand. Once between the plates, I shoot compressed air in the gap to help cool it down even quicker. For compressed air, I charge up a portable air tank from my compressor and use that up. Those little red air tanks are sold every where.
Wear safety gear. I wear heavy welding gloves on both hands. I use a long tong to grab the foil pouch. I make sure the oven is OFF (getting shocked at 240v will kill you!) when pulling out the (scary, hotter than hell!) foil pouch. Holding a 1950F degree burning hot foil pouch with a blade in it is no time to figure out you are not ready. Practice a few times first before your first run.
Note: Picture is for illustration only.