Thread: Anti-scaling compound--two thumbs up!

Originally Posted by L R Harner

the chunkyer and blacker scale is most the time from gross over heat as if you keep the temps down even in my kiln scale is not to bad

Agreed. I get a thin layer of scaling from my kiln at normal heat treating temps. The normalizing cycles at slightly higher temps do contribute a bit more, though.

Originally Posted by Mike Blue

The Advanced Technical Products folks will sell directly to the end user, from one tube to a case.

This is what I use. I second the recommendation.

Thanks, Mike. For some reason I thought you'd told me that you use PCB, and USAKnifemaker had some, so I grabbed it. I think I'll try it a few more times and see if I can't get the hang of it.

Originally Posted by ChrisMeyer

Josh,

I cleaned my blades with Acetone, mixed up the ATP, then tried to apply it with a foam brush. The brush seemed to work fine, but I was getting very uneven coating. I determined that Acetone was insufficient for degreasing, so I used some Gun Scrubber solvent/degreaser that I had laying around. That worked better, but if you miss any spots the ATP wont stick to them.

Once the blades were properly cleaned, i just dunked them into the ATP. You can't get much easier than that. The ATP dries pretty fast, so you don't have to wait too long to put on a second coat.

I appreciate the photos and explanation, Chris. That looks pretty simple. Hey, I have some Gun Scrubber "hanging around" too...

Applying the stuff while the steel was hot really wasn't too hard, so it seems like six of one, half dozen of the other between doing a thorough degreasing. Unless I can't get the results I want, of course.

There used to be a brand called Turcoat, but I think it went off the market due to health issues. It worked pretty well too. ATP, PBC sound alike.

As someone interested but completely untrained: is there some way to avoid getting scale without using an anti-scaling compound?

Originally Posted by Jovus

As someone interested but completely untrained: is there some way to avoid getting scale without using an anti-scaling compound?

Yeah, there are a bunch of ways. Anything that prevents the steel from contacting oxygen will reduce or eliminate scale.

Mike Blue, Tim Zowada and others heat their blades in specially formulated molten salts. That's how the production razor companies do it, too. Since the blades are immersed, they don't oxidize.

Knifemakers who use stainless steels often wrap their blades in metal foil to keep them isolated from oxygen. This doesn't work as well for carbon steels because you have to get the steel out of the package to quench it, and by that time it's cooled too much.

In a forge, some guys will put a piece of wood in along with the blade. The burning wood uses up the oxygen.

On a more industrial scale, filling the heating chamber with an inert gas (I think they use argon) is another approach.

Lots of ways to skin this cat, but for small-scale guys like me, the anti-scaling compounds are the simplest way to solve the problem.

Good question.

Josh

Well, I finally got around to heat treating some blades. I coated the blades with ATP Anti-Scale Coating. There are no real directions on the jar, but Brownell’s website says that, after heat treating, "parts rinse clean in hot water". Not!

These were the blades; two straight razors and a knife. I clearly ground my first razor way too thin before heat treating (it’s the one in the middle), I didn’t think the other was too bad. (I was wrong.)

The blades coated with ATP Anti-Scale

The ATP stayed on while I was heating the blades in my forge. My blades were made of O-1, so I was shooting for 1475 degrees F, with a 15 minute soak time. I don’t have a temperature controller on my forge, but I can get it to stay within about 3 degrees +/- of my target temp. I quenched all of the blades in Park Metallurgical/Heat Bath’s AAA quenching oil. (By the way, Kelly Couples is now a distributor for Heatbath’s AAA and #50 oils. He sells them in 5 gallon pails.)

The first razor I heat treated came out pretty straight. However, as it cooled, the spine curved to one side. Interestingly, the edge actually stayed pretty straight. The second razor, the one ground too thin, ended up with a edge that looked like a potato chip –the Ruffles kind! The knife blade came out okay.

As for the ATP, it may have kept the blades from scaling, but I couldn’t get it off. Hot water did nothing to it (I didn’t try boiling). I ended up grinding most of it off. Even then, it didn’t come off easily. I may have screwed up the application and removal of the ATP but, since there are no specific directions, I don’t really know. I emailed the company, Advanced Technical Products, Inc., for directions, but I haven’t heard anything back from them.

Since the edge of one of my razors looked straight, after tempering, I surface ground the blade to get the spine flat. I was able to make it flat, but by that time the blade was too thin to re-grind any bevels on.

So, my first test of ATP didn’t end very well. I couldn’t get the stuff off, I’m not yet sure whether it lessened decarb, and I trashed two out of three blades (my lousy grinding). I’ll have to grind out some more razors and do some more testing. I think I'll leave the next blades much thicker for heat treating.

Cool post, Chris. Thanks for sharing. A few items for thought:

I was able to remove my anti-scaling compound by boiling the razors. This is still well below the tempering range, so it's pretty harmless. I'd give that a shot next time.

I also see what looks like some tufts of bare koawool sticking out of your forge. You should probably coat that with some satinite or something similar. Uncoated koawool gives off free silicates when heated, which is supposed to be very bad. I'm not sure what they do, but apparently you don't want to be breathing them in.

On your hollow grinds, consider not taking the grinds all the way to the top of the spine prior to heat treating. That leaves some extra thickness up there, which reduces the likelihood of warping. Also, if you're having trouble with warpage, make sure you're doing three normalizing cycles prior to hardening to remove stress and even out the grain structure. In my last batch of blades, I ground the edge on one of the blades to .015", but I got zero warpage. I've had blades as thin as .010" come out without any issues. I've also potato chipped a lot of blades. When it happens it's usually when I am a little sloppy on my grinding and have some unevenness.

Josh

Josh, thanks for the tips.

The Koawool is actually on the outside of the ceramic forge shell. I'm not sure if it get's hot enough to give off silicates. However, I have some Satanite, so I'll avoid the risk and coat it up.

My blades were ground from Starrett spheroidized annealed O-1. I didn't normalize them, so I'll give that a shot next time.

I could only use hot water from the tap, as my wife was cooking in the kitchen and I was pushing my luck just by cleaning blades in the kitchen sink. Also, Brownell's site claimed hot water would work. Next time, I'll boil some water before I even start heat treating.

Sounds like your steel is fine; grinding does impart stresses, especially if the blade gets really hot. (I use a magnet to hold it when I'm grinding flat surfaces, so it can get pretty toasty.

A good $20 investment is a small electric hot plate. I use mine to heat my quenching oil and anything else that needs to be warmed up. Along with the toaster oven, it helps keep peace in the house.

Josh

i bet you start standing your blades up (on spine edge up) that the side to side warp will lessen (also make sure you quench in a updown slicing motion
you can also get a pair of gloves and tweek a semi hot blade if you catch it before its at room temp to straighten it out