The chef's knife is the largest profile blade that I have forged. I use a single burner Ellis propane forge that is plenty hot enough, but I do have quite a lot of scale after each heat. After I pull the steel out of the forge at a bright orange to yellow heat, and after taking the time to brush off the scale, I only have a few seconds of forging heat left before I have to stop hammering. To buy myself a little more time, and to make it easier (and faster) to brush, I started to sprinkle some flux on the steel before putting it back in the forge for another heat. This helps a lot with reducing the oxidation, but I'm wondering if there is anything detrimental to doing this before every heat. I use bubble alumina on the bottom of my forge, and it seems to take it well, but can it have a negative effect on the steel by doing this repeatedly? I started with the suggested bar stock, but it is extremely thin before reaching the dimensions suggested for the forged shape. I was only able to squeeze out a blade that is about 1-3/4" x 8" before I felt as if it was already too thin. Can repeated use of flux cause this? Thanks!
Jeff Heinen
Andrew Smith
Alex Monroe
Benjamin Abbott
Ironically, I think that all of the attention that you are paying to the scale is the problem. If I am going to brush off scale, it is usually only for the last few heats, when I would be afraid that I would be pushing that scale down into the almost-finished blade, and leaving hammer marks. For the majority of the forging, I don't worry too much about it. What you said is that you spend a lot of each heat dealing with the scale, and only a little at the end is dedicated to the actual forging. This means that your steel is going through way more heating cycles than it should. Each of those cycles develop scale, and the more scale you develop, the less steel you end up with in the end. It takes me about 45 minutes to forge out a kitchen knife from a bar of steel, any more than that, and you lose more steel to scale.