DIY Anti-Scale Compound

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Yeah, Troop, I am thinking it is more the atmosphere than the ink. There is so little solids in marker ink that I doubt it would survive 1500F for long.( resisting FC is an entirely different thing). However, I have discovered that the white metal marker pens will stay on through 1900F HT. I mark the tangs of stainless blades with metal type and other info ( or you will never be able to tell one from another), and do stainless HT in batches. I have found that the white pigment just burns off to leave a titanium oxide stencil. It makes it easy to ID the blades after HT ,too.

Stacy

Stacy, Do you mean the pens with the paint on the inside, that you have to press down on the tip for it to come out?
- Thanks
 
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Well the mix didn't quite work as planned. I got a good intial coating, but it flaked in the oven and beaded up once it melted. I don't think I had the boric acid dissolved enough, so it went on too thick. I think I'll switch to Stacy's formula. Stacy, have you found that you have to use a faster quench with the coating?

The places where it beaded up came out just as pretty as they were when they went in, though!
 
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You can pick up boric acid in most any independent pharmacy. I stock it in 4 oz and pound sizes. It can be used in a lot of things. They used to make boric acid ointment for infection and boric acid solution for an eye wash. It can be used by itself for roaches. It does help to add a little sugar to the mix. I use it in a diaper rash ointment I make for babies. So it is not all THAT toxic by itself. If your pharmacy doesn't have it, I am sure they would order it for you. Hope this helps.
 

Stacy E. Apelt - Bladesmith

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Troop,
Yes, those shake-em-up paint markers. They make ones especially for metal making. Fastenal has a rack of them. They come from fine point to a wide tip, and in several colors. The regular white paint markers from Walmart/K-mart work fine ,too.

Stacy
 
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Troop,
Yes, those shake-em-up paint markers. They make ones especially for metal making. Fastenal has a rack of them. They come from fine point to a wide tip, and in several colors. The regular white paint markers from Walmart/K-mart work fine ,too.

Stacy

I'm guessing that it's specifically the white ones that work well right? Titanium dioxide is the white pigment and it's pretty durable stuff.

-d
 
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Boric acid and alcohol is the standard cheap and easy anti-fire scale dip for our industry ( goldsmith). I have a 50 pound barrel of it.

If you wanted to make a batch of anti scale try this (Quantities are in fluid oz.):
( This is off the top of my head, so feel free to tweak it as desired)

5oz boric acid (roach powder)
3oz borax ( 20 mule team is fine)
8oz denatured alcohol ( the cheap paint store variety, not the drug store stuff)
2oz satanite ( our old refractory friend)
3-4oz ocher (any color ocher - finely sifted dried red clay would probably work)
3-4oz gum tragacanth ( bottle of leather edge dressing)
water

Mix,adding additional alcohol until it becomes a well mixed thick paste.Add water until it becomes a slurry ( I think it needs some water to allow proper hydration and solution of some ingredients). Try it on a piece of steel to check results, and adjust the ingredients as needed. Keep in a tightly capped container,away from heat. Shake well each use, and paint it on with a small brush, or dip the blade and let the excess run back into the container. A batch should last for a long time.

Do not use above 1600F as the borates will become corrosive.

Stacy

Stacy, thanks for sharing this. I mixed up a batch, pretty close to your proportions and tested it on some o-1 pieces, finished to 220 grit, normalized and quenched in warm oil from 1500f. It stayed on well throughout the HT process. a few bits popped off in the quench but the rest is stuck like cement. so far I have tried boiling, denatured alcohol and overnight in WD40 which has the best results but it still looks like I have to sand to get back to clean steel. Is this normal? and do you have any recommendations for removing the coating without sanding?
Thanks
Robert
 

Stacy E. Apelt - Bladesmith

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Just a note that this is a seven year old thread. It is best to post a link to the old thread and post a new thread. You can also copy and paste the info in your new thread.

All blades need sanding down after HT. The skin is still affected regardless of any coating. The degree of decarb and scale is reduced, but not completely eliminated.

Even if it was unaltered, you still need to remove about .005" each side ( or more) to get the edge down to .010-.015". At HT the edge should be about .030" to avoid warp and "bacon edge".

After HT go back to 220 grit and after the bevels are reduced and flat, go up the grits again.
 
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Just a note that this is a seven year old thread. It is best to post a link to the old thread and post a new thread. You can also copy and paste the info in your new thread.

All blades need sanding down after HT. The skin is still affected regardless of any coating. The degree of decarb and scale is reduced, but not completely eliminated.

Even if it was unaltered, you still need to remove about .005" each side ( or more) to get the edge down to .010-.015". At HT the edge should be about .030" to avoid warp and "bacon edge".

After HT go back to 220 grit and after the bevels are reduced and flat, go up the grits again.

Agreed, I always re-sand the blade after HT at the last grit. I just wanted to know if it was normal for the coating to stick like my results and if there was a way to remove it, prior to sanding. based on your reply, I'm assuming my results are normal.
Again thanks for taking the time to share the formula!
Robert
 
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I've used boron nitride spray and it reduced scale quite a bit, I think. It's been a couple years since I've done my own heat treating.
 
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This thread may be old but it's fascinating! We use Brownell's anti scale under the clays for differential hardening but I'd never really thought much about the theory/ingredients/minutae of how it worked. :)
 

KnuckleDownKnives

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I feel really dumb after reading this post..... But I'm soaking it up like a sponge...
 

Stacy E. Apelt - Bladesmith

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Agreed, I always re-sand the blade after HT at the last grit. I just wanted to know if it was normal for the coating to stick like my results and if there was a way to remove it, prior to sanding. based on your reply, I'm assuming my results are normal.
Again thanks for taking the time to share the formula!
Robert

I didn't respond to this back in January.

Yes, a good blade coating will somewhat bake onto the blade in HT. It will need to be scrubbed/sanded off. An overnight soak in something like Sodium Bi-sulfate (Ph Down) is a good is a to remove any hard scale.
 
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I've been using roach poison for a couple yrs as an anti-scale for carbon steels. Heat blade a small bit so powder melts forming a clear glass looking coat. Stays on during HT just fine, then soak in hot water and melts right off.

Ken H>
 

Stacy E. Apelt - Bladesmith

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Roach Powder - Boric acid. When heated it melts and forms a thin layer of what is called "borax glass", which helps exclude oxygen. The glass is water soluble, so a soak or biol in hot water removes it.
 

synthesist

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H'mmm I can understand how important it is to mark blades whose steel type/composition will be indistinguishable after heat treat. Using a shake em up paint marker sounds okay to me but wouldn't one of those $20 diamond tip vibrator markers used on the tang also work great? I've used those when I'm cutting blades out and it seems to keep me on track easily during the whole process right up to heat treat....................

Just my 2 cents

Corey "synthesist" Gimbel
 
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I got this stuff at Home Depot for 2.98.


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Stacy E. Apelt - Bladesmith

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The problem with using something like generic roach powder is that if you look at the ingredients list you see it is marked "active ingredients". That is 99% boric acid, but the inactive ingredients .... which are not often listed ... may be as much as 50% of the bulk. These can be lime, gypsum, silica, chalk, etc.

99.9% boric acid sells for about $2.50 a pound, so it is just as cheap as the unknown grade roach powder.

I just checked eBay and a five pound bag is $12.50 with free shipping. 10 pounds is $19.95 with free shipping. If you buy it by the 50 pound pail, it cost a dollar a pound.
 
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It's been working well so far. And if you sand to at least 220 grit it will flake off when you quench.

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Stacy E. Apelt - Bladesmith

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I am sure it works fine for our needs. I was just pointing out that many folks think it is cheaper than boric acid, which isn't always so.
 
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