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

I've read mixed reviews of different anti-scaling compounds, so I thought I'd order some and see for myself how it works for me. I got the PCB anti-scaling compound from USAKnifemaker.com, which costs about $20 per pound.

Anti-scaling compound is used during heat treatment to prevent the steel from coming in contact with oxygen. At heat-treating temperatures, steel reacts almost instantly with oxygen and forms this nasty, super-hard substance called scale. It's kind of like instant rust, and it causes the metal to bubble on the surface and flake off in big chunks. It's a real bear to grind off when it occurs.

This evening I gave the PCB a try with my new heat treating oven. I heated two blades up to about 800 F, then sprinkled the compound on with a spoon. It was more difficult to do this than I expected, especially with welding gloves on, so I ended up with an uneven coating. In the places where it was thick enough, it melted and bubbled, eventually smoothing out like glass.

This was factory-spheroidized O1, so I just did one normalizing cycle, then a 15-minute soak at 1500 F and a quench into Parks AAA oil. After the blades cooled, there was no warping, even though the edges were ground to about .015". (I went a little thinner than I intended there. I've gone as thin as .010" with no warping, but if the grind isn't even the edge can start to "potato chip," or get waves and ripples. This is a good way to make an 8/8 into a 6/8.)

I cleaned the blades by soaking them in some near-boiling water, and I was very pleased with the performance of the compound. They came out almost cleaner than before the heat treat. If I had gotten a little bit better coverage, one of them would have been practically ready for the buffer.

I need to experiment with better ways to apply the compound. I made a little shaker out of a jar with some holes drilled in the lid. If that doesn't do it, I'm just going to buy an actual salt shaker, as the powder is really fine stuff.

You guys who heat treat in forges could probably really benefit from something like this. My heat treating oven is much gentler than a forge, so you might still get some scaling, but I imagine it would be greatly reduced.

I'm very glad I tried it out.

Josh

Josh,

I tried the PCB stuff a couple of times. Like you, I found that it works but is a PITA to put on. I found a different brand that is a liquid, which seems like it would be easier to use. I bought some, but I haven't gotten around to trying it yet. If you're interested, Brownell's sells the liquid ATP Anti-Scale Coating.

Does the scale have to be removed? I know a shiny blade requires it being removed. But if you don't want a shiny blade?

Thanks for posting this,Josh.I'm not a razor maker by any means,but I find these posts very interesting.Please keep posting when you can,it's neat stuff.

Chris,

Thanks for the link; I've read good things about ATP. I went with the PCB because I order a lot of other supplies from USAKnifemaker as well, so there's no extra shipping. Do you apply the ATP when the steel is cold? Brushing a liquid on cold would probably be easier. Using the PCB is a lot like applying borax for forge welding--takes a little practice. I think the salt shaker approach will make it fairly painless, though.

DwarvenChef, you'd probably want to remove the scale even if you weren't going for shiny. The guys who do great forge-finished work usually soak their blades in a mild acid, like vinegar, to remove most of the crud. You end up with a dull gray finish with a lot of character. (Have you seen Raymond Richard's work over in the Bladeforums knifemakers section? It's stunning...)

Josh

For application, have you considered a small flour/sugar sifter?
You could block off all the mesh underneath except for a rectangular section about 1" wide and have a perfect rectangular powder dispenser.

DC
coat the lower part of the blade to save it and jsut let the top get all scaley and nasty (to some ) thats how you will want to do it
BTW
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

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.

Interesting idea there Butch, have to write that one down to give it a shot. After I heal up we are firing up grandpa's forge and see what we can do with it

Originally Posted by JoshEarl

Do you apply the ATP when the steel is cold? Josh

Josh,

I didn't know the answer to your question, but I had the ATP and some O-1 blades that needed to be coated, so I gave it a shot.

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.

Now I just need to heat treat the blades and see how the ATP works...

O-1 Blades


ATP & Gun Scrubber


Coated Blades