PBC Special (2000F) anti-scaling. Foil is DEAD. Almost :)

[rashid11]

OK,

long overdue. I got the "PBC Special" a few weeks back, but due to heat and stuff hasn't gotten to it till now.

PBC powders protect tool steel, during HT, from scaling and decarb. Many of us have been using "regular" PBC - rated to 1600F, to HT regular low alloys: 10xx, O1 etc. Great results, very consistent.

For stainless and higher tool steels, the stainless envelopes were what we did to protect the steel. Foil has its problems . So, enter the PBC Special - this one is rated to 2000F.

So ... got me blade heated up to about 500F. ATS34, A-la-Loveless hollow grind tapered tang.

Got it outta oven, PBCS in sifter, shook the thing over the blade and .... the powder did that "rain drops on microcloth" thing ... none of it stuck ! Hmmm. back into the oven, 700F.

Got it out, sprinkled the powder .. bingo... The behavior is dift from regular PBC - that one sizzles and sticks to blades @ 500F. Even bubles up ! This one is very quiet. Does stick, a bit, but no sizzling, no smoke, no bubles.

Shook the thing over the blade and bolster area. Handle, toward the end, got nothing. For contrast... even though most of us know what open atmosphere ovens do to steel @ 1900F.

So, back into the oven. Hit 1400. Stabilize for a few mins. Hit 1920. 5mins.

Anticipation ... butterflies and everything.

Got 2 massive Fortal (what a pity that guy wuz driven outta biz !) Alum blocks next to oven. Gloves, tongs, blade out and onto the block it goes.
Another one on top. 40 secs later blade cool to the touch....

Remove the block atop of blade and ....

...

...

Tada !!! Some of the PBC came off when it cooled and what do I see ? Nice clean steel ! No pitting, no discoloration. Have not had a chance to hit the blade with a file yet, as into toaster oven it went, right away, for tempering .

In few hrs I should have some idea on hardness, but I have no reason to suspect it won't be rock solid 60RC.

The PBCS looked interesting, almost like a greenish glaze on those fired clay mugs. Not the dull black exterior of "regular" PBC. Both come right off with application of hot water.

So ... is foil dead ? I think it still has its uses ... bloodletting, for example ?
Of course, one has to be master the method 100%, for SS . Some decarb we get with carbon steels, due to mistakes whatnot, can be removed, in most cases. But the one that comes from 1900F is MUCH worse. So before you ditch the foil and use PBCS on a customer blade that you put plenty of time into, make sure you get the technique down.


Next time I will heat up the blade to about 800F, before application of powder. Even 700F is a bit on low side. Need to get a finer sifter. And cover the whole blade... exposed handle area didn't look too good

Might have to adjust the application method too. For now, I sprinkle with a sifter, over some comon kitchen foil. A bit tricky, as both hands are BZ - one has the sifter and the other one tongs with the blade.

Next time I will put the foil over may be piece of plywood. Put the blade atop and then apply the power, flipping the blade over when done with one side.

Foil is to gather and re-use the excess of PBC . Ply to provide for some thermoinsulation. May be even cut a 12x12 piece out of my welding blanket and use that as the base for foil.

[rashid11]

Hardness checks out 100%. After 2hr temper @ 360F I can barely touch it with a file. Whatever was covered with PCB came out w/o any scale and decarb. Most of the PBC "glaze" came off during plate quench (I guess same way glass would crack during a sudden drop in temps).

so there you have it

[mdagley]

I just visited their (Rose Mill) website. They claim this stuff has an operating range of 1650 deg F to 2250 deg F.
They have it priced at $85 for 5 pounds, which doesn't sound bad. Any idea how many blades you can treat with 5 pounds?

-Mike-

[rashid11]

A sh*t load - about as scientific of an answer as I can muster.
Use my application method - over a piece of foil etc, so u can collect
and reuse the excess powder and you're in biz for a loooong time.

[Woodchuck Forge]

Could you take the flake and put it into a mortar and pestle to regrind it?? it might be interesting to try. I have done this in the past with flux. Actually I went to the thrift store and picked up an old blender for 50 cents and ground the anhydrous up with it. If you could you would probably have a lifetime supply.

Chuck

[alexkuzn]

Do you have occasional decarburized spots like I have with regular PCB?