Hung out with an old timer at the guild and it made me rethink annealing

Met this guy named Bob at the local blacksmith guild meetup last Saturday, he's been at this since the 70s. I was showing off this knife I made and he asked how I did the annealing. I told him I just heat it and let it cool in the forge, like the basic method. He laughed a little and showed me his trick of using a bucket of dry sand to slow cool it way more evenly. I tried it on a piece of coil spring I was flattening and the difference was crazy, it cut way smoother and didn't crack at the edges. Made me realize I've been skipping over a lot of the small details just because the YouTube guys make things look fast. Now I'm wondering how many other shortcuts I've been taking without knowing it. Has anyone else had a random tip from an older smith totally change how they do basic stuff?

3 comments

3 Comments

alicesingh1mo agoMost Upvoted

Oh man you just hit on something I haven't seen anyone mention yet. That dry sand trick might accidentally be introducing a different kind of heat cycle depending on how deep you bury it, like a poor man's differential annealing lol. I bet the real secret Bob is working with is just the consistency of the cooling rate, which a lot of us ignore when we're rushing a project.

finleyf881mo ago

Right, @alicesingh caught something I've been noticing too, it's like the difference between a home cook and a real chef knowing when to let things rest. That slow cool in sand is the same idea as letting a steak sit before cutting, or letting concrete cure right. We get so used to speed from watching clips online that we skip the boring steps that actually make things hold together.

gavinw451mo ago

That dry sand trick works pretty well but you gotta make sure it's bone dry first. Any moisture in there and you're basically steam tempering the thing, which gives uneven hardness later. Also for coil spring steel you probably don't need to anneal it that slow. Simple heat to non-magnetic and bury in a bucket of wood ash works just as good for most tool steels. Bob's been at it since the 70s so he's seen a lot, but some of those old tricks were for stuff that was harder to control. Thermocycling a couple times before the slow cool does more than just burying it hot.