Scale

[Derrick]

Gene or Bob

I'm new so not sure if I'm asking the right Q to you guys. But here goes ..I use 440-C and D-2 and do my own tempering. My Q is .. Is there a way to reduce the scale and discolouration I'm still getting even after using the foil .. Sometimes they come out very nice and can remove the little discolouration with hand sanding and the next time I have to go back to the grinder and a new belt. I had heard that there is a paste that can be put on and let dry before putting in the foil??

Appreciate any help you fellows can give me.

Derrick

[Bob Warner]

Should not need any paste.

Make sure you put something flamable, like a small piece of paper, inside the foil with your knife. This paper will burn inside the foil when it gets hot and that will burn up the oxygen inside the foil. No oxygen, no scale. You also need to make sure you are sealing your foil good enough. If air can get in, all bets are off and the scale is free to form.

[Derrick]

Bob
Many thanks for your help will give it a try on my next batch and will let you know how I make out.. I do double folds on my foil so unless I some how get a tiny hole in the foil they should be air tight.. I think.

Thanks again for your help.

Derrick

[J. Hartt]

Derreck, We use this stuff called "turko", without foil on 440C.
I'll grind to 220 grit on a vertical wheel, dip in turko, heat treat, then back to the 220 to remove any discoloration, 400, 600, 1200 grits, buff.

[Sweany]

on the top of the page here is a button (how to's) there is an article by Terry primos that might hep you out.

[Brett Bennett]

Sweany,

I use the PBC that Terry uses in his tutorial, but it's only good for carbon steels as it's only rated for 1650 degrees.

[Derrick]

Sweany
thanks for your reply.. My problem is the temp I use 1855 deg and 1875 deg so that product will not work ..
Q what would happen if a person used Turko paste and let it dry and then put it in foil wrap?? has anyone tried this. ??

Thanks

Derrick

[J. Hartt]

Derreck, I found the info.
The stuff I use is made by DuPont for the auto piant industry.
Its proper name is Lucite, and the # on the can is 3608S(product # I think). Also on the can is 'Fast Thinner'. It's a orange liquid that smells like piant thinner, and has the consistency of thin syrup.
Check at Acklands or get a friend in the autobody business to get you some. It aint cheap, but it works real good. Just dip, hang to dry for 20 minutes, then heat treat -no foil.
Hope this helps.
TTYL ,Jeff

[Derrick]

Jeff
If it works as well as you say it will pay for its self as foil is not cheap either..

Many thanks for your help..

Q are you thinking of coming to the Kamloops show? if so let me know.

Derrick

[J. Hartt]

Derrick and all others reading this post: I was WRONG, WRONG, WRONG. I have found the CORRECT info. The stuff is called TURCO and is available from K&G Finishing supplies. I checked their website, www.knifeandgun.com, and found it under heat treat foil. I have never used foil so I can't compare the two, but this stuff works great.
First wipe with soapy ammonia and let dry(5 mins), then dip in Turco and hang to dry for 20-30 mins. Heat treat as usual. The blades come out black, but a quick turn on the disc with 220 grit, then 400 grit , then 600 grit, then 1200 grit , buff and bada-bing they are done.


The Dupont 'Lucite' is the thinner to be used if the Turco gets too thick.

[WinDancer]

You don't mention what you do from the oven-

I go straight to the oil, still in the foil. The blades stay clean with no scale.

My first experience, removing from the oven, trying to cut the foil and remove the blade, and get it into the quench while still at optimum temp was enough for me. Laurel and Hardy do knifemaking! And the three burns were no fun either.

My second experience, with the dip, was to open the oven and find all three blades welded to the metal support that held the blades.

Now, just the foil with a pinch of sawdust inside, and straight into the quench. THEN the foil is removed and into the tempering oven.

Let us know what you finally do and what you are happy with.


Dave

[Derrick]

Dave

When I take them out of the kiln I cut them out of the foil straighten them and let them air cool by fan. I am using D-2 and 440-C both are air hardening .. I heat treat them at 1855deg for the D-2 and 1875Deg for the 440-C but understand can use the 1855 deg for both .

Then into the oven at 350 deg for one hr cool to room temp and then another hr at 350 and the D-2 is about a 58-59 RC and the 440-C is 58RC

Then its to the shop and take off what ever scale is there.. The batch I just finished tonight I tried something different.. added the paper as mentioned but also tried an old blacksmith trick told to me by a friend and that is to coat them with regular bar soap and when out of the kiln soaked them in a vinigar and salt brine for an hr. so will see what tomorrow brings re how hard the scale is to take off. Have picture of what they looked like but not sure how to enclose as am new at this.

Derrick

[floridafred]

Windancer, I also had the experience of trying to cut 01 and 1084 out of the foil to quench. I only had to try that once to know I didn't like it. I bent one blade dropped another (twice). My next attempt I tried a little trick. I made one envelope for a blade sealed on three sides and long enough to cover all but one inch of the tang. I made another envelope sealed on three sides and long enough to cover the tang. The second envelop is slipped over the tang overlapping the first. As much air as possible squeezed out and a piece of shopping bag about the size of the knife placed inside.

At quench time I grip the tang and only the envelope that covers it to remove from the overn. With a pair of plyers I pull off the lower envelope which covers the blade and quench the blade. I tried this twice and had very good results. It was also quite easy and 400 grit hand sanding cleaned up both blades nicely.

I am going to experiment with this process some more but I've recieved my shipment of the powder used in the Terry Primos tutorial and began using it. It works great also.

[wrathlord]

I have found ,for me at least,that buffing with crocus on a muslin buff removes alot if not all the scale,all that is left is a greasy film that can be wiped off.

[Derrick]

How does one add a picture ??