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Anti-scaling Paint

Discussion in 'Heat Treating' started by John Noon, Sep 14, 2016.

  1. John Noon

    John Noon Well-Known Member

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    I know someone here has used the anti-scaling paint when heat treating and I have a question about application.
    Steel being heat treated is AEB-L 1/16" thick
    Tried dipping a small blade and coating was twice the thickness needed minimum
    Second blade was coated four times with a foam brush.

    Both were allowed to air dry for at least 24 hours before hitting the furnace. Both blades were as black as the night when the coating fell off in the quench tank. Just a little decarb to say the least but luckily no grinding before heat treating so the damaged layer will hopefully be gone by the time shaping is done

    Thinking maybe I should bake the coating before putting in the furnace?

    Did a little research on the brand I chose ATP-641 and it appears to be a love hate relationship, some say it works and others like me end up with heavily blackened blades when working stainless.

    will have another batch later this week and plan on four coats to build up the thickness, pre-heating the steel to help burn off moisture and speed up cure time. Plus I might add in a step in the heat treating process of 250F for 10 minutes to reduce any moisture in the coating that could possibly be causing cracks and exposing the steel to the air.

    Anyone have any other ideas or suggestions (foil wrap) yes I have that as well but wanted to try out the paint. Going to experiment with using it to form a hamon in a 1095 blade this weekend as well.
     
  2. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    I can't help you John. But, I sometimes get really intimidated when I post my really simple questions when I read yours. I really hope that one day I get to the level where I'm doing the sort of advanced stuff that you work on. Don't be offended but I'm glad to hear that even the veteran knife makers have problems and issues. A different degree of problem, sure but still.

    Sorry, I'm still working on the straight bevel problem and getting my forge finished for heat treating. I've got a truckload of problems i don't even know about coming my way methinks

    I apologize for the tangeant...
     
  3. John Noon

    John Noon Well-Known Member

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    LOL no expert not like the guys who hang on the sidelines and post up awesome stuff I only have a year of knife making and over half that time has been in a hotel far from home. The catch sometimes is I try something, fail, then look for answers to why and try again.
    Really have to change that order :whistling , Like stabilizing wood where I read the directions after my first blocks to see if there was something I was missing. Turns out it was patience
     
  4. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    patience is something i need more of too... again, i apologize for taking this off course. I wish i could help you out with your hamon question.
     
  5. John Noon

    John Noon Well-Known Member

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    I have the manufacturer's documentation, and just notice the email notification took me here and not where the question was posted?

    Weird.

    For Condursal had mixed results dipping and hanging the blades, on occasion the Condursal lacks enough thickness at the pommel. Next ones I do are going to get sprayed onto a blade that is hot to the touch or warm so the coating is even. sort of related

    and for heat treating AEB-L I use information from another manufacturer of what is technically supposed to be the same thing. I will post them up on my web page shortly or you can check my blog
    AEB-L


    John would you happen to have your AEB-L heat treating process handy or anyone else? Have been searching on the web and haven't found any straightforward recipes, just long threads that only seem to add more confusion to my already confused state.
     
  6. cuatroXcuatro

    cuatroXcuatro Member

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    Thanks John. I deleted my post right after I found the info I was after on your blog. So far I've been having good results with Condursal. I like to do everything in shop so I'm always researching other types of steel. Looks like AEB-L needs a cycle of cryo which means I would need to use dry ice.
     
  7. John Noon

    John Noon Well-Known Member

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    Cryogenic cycle is not mandatory for casual use knife. Now for professional use like fish processors or guides then it is not a bad idea,

    I found getting the steel below zero within thirty minutes is more important
     
  8. Grayzer86

    Grayzer86 Active Member

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    Hey @John Noon Im curious to know how straight your blades are coming out from the oil quench. I have been using AEB-L extensively and my experience is that its extremely warp prone, even with plate quenching especially during dry ice treatment. I need to try the talc inside the foil. Have you run hardness tests on any samples to compare to your charts. Im not at all trying to question you, its just that those published charts are not matching up with my own results. especially the tempering charts. The subzero cycle seems to be debated, but i am finding as quenched hardness is different with and without cryo, which matches what i have read from some others. I believe the posted tempering chart is for non cryo results. I am also seeing a noticeable difference in edge retention in a couple kitchen knives i made to test, likely from the higher achieved hardness. Both got the same temps, however one was done without cryo. Its a bit of an extreme test because the knives were ground to absolutely zero before sharpening back. The non cryo knife was never hardness tested so i have no idea where its actually at. I have had samples tested, and I am coming out of the dry ice averaging just under 65. The tempering chart shows a hardness of roughly 60 from a 350 temper in my kiln verified with a secondary thermometer. With cryo I am hitting 62-63 after a 350 temper. Just as a reference i will post the process I use. This is not my invention, it is a process I adopted from Devin Thomas, so credit where its due.

    - wrap blades in 309 foil
    - preheat oven to 1725
    - insert blades at 1725, allow to come to temp and soak 10 minutes
    - plate quench until cool
    - ramp oven to 1965 and equalize
    - place blades back in at 1965 and soak 12 minutes (some clearly a bit longer as i am quenching the others)
    - plate quench with forced air between plates
    - remove from foil and place in dry ice and 99% alcohol

    At this point I am pretty steady at 65 with the odd 64. 350 is getting me an average of just under 63 if i add the results up. All things considered, a temper at 400 should theoretically put me right around 61, but I have not had that tested.
     
  9. John Noon

    John Noon Well-Known Member

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    I cut out the blade shape but no profiling
    With the condursal applied I insert the blade at 1500F, ramp to 1750 let soak them ramp to 1950.
    Plate quench until warm too the touch then transfer to a plate clamp and stick in freezer for an hour.

    With foil I plate quenched in the foil and 90% of the blades came out warped. Found out the forge welding temperature of the foil was close to the austenizing temperate of the AEB-L leading to sticking of the foil.

    The ones I put through the cryogenic cycle in foil warped, did an experiment and found that before the blades reach zero they are easily bent.
    Freezer cycle then cryogenic cycle with bare steel went much better to keep things straight.
    I have had two knives below 60 and did not appear to harden, tried second cycle and they hardened. Tossed them into recycling container.
    Been using hardness files and after temper the knives are above 60. Hope to spoil myself and get a bench mounted unit this summer.


    One thing I will admit this is the most troublesome steel I have worked with for keeping straight when using 0.07 thick for fillet knives.

    There is more info on the hype free knives forum worth reading,
     
  10. Fred/A

    Fred/A Active Member

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    Boric acid (borax) will do perfectly. Blades come off of ht clean as they where before quench. It is an old watchmaker/jewelller's trick for heat treating pieces that can not be grounded or retouched after ht.
    Wet the blade with rubbing alcool, dust the blade with boric acid (not to much, just a little coating) and put it in the oven. The boric acid will form a plastic like coating on the blade, preventing decarb and scaling. Just have to peel the rest of plastified boric acid after quench, comes off easy.
    Most of the anti-decarb or anti-scale compounds are made with boric acid if you do some research about diy compounds.
     
  11. John Noon

    John Noon Well-Known Member

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    I have lots of borax and will try this on a carbon steel blade , not sure about stainless steel until I can locate the max safe temperature for borax
     
  12. Fred/A

    Fred/A Active Member

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    I think it's around 1600f... didn't think about that. But it will work with no trouble for carbon steel.
     
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  13. John Noon

    John Noon Well-Known Member

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    Okay then about the same as ATP-641 which works real nice when properly applied. Having a blade come out of the oil essentially clean and smooth is a treat, even considered a small blade test with the cutting edge formed down to a millimeter just to see if it would work.
     
  14. cuatroXcuatro

    cuatroXcuatro Member

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    I haven't tried working with AEB-L yet was just researching options, sounds like it's too finicky for me. Have had good luck with Condursal on CPM154 and have had no problems with warpage even with 1/16th blades 75% finish ground. Does the borax work with SS?
     
  15. John Noon

    John Noon Well-Known Member

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    No Borax working temperature is way below temperatures needed for stainless steel. Like Condursal on Carbon steel safe temperature starts at 600 C but better to go higher due to cooling of the furnace when you open the door.
     

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