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View Full Version : Anti-Scaling Compound, what's everyone using?



Willy
10-11-2011, 12:31 AM
I have a few small parts to heat treat and would like to avoid the issues associated with scale during the heat treating process.

I realize stainless steel foil and a carbon pack would be simple but I don't have that option. Also I understand that a number of effective over the counter products are available, but again that option too is not available due to the time constraints of ordering these products vs. when I need these parts heat treated.

So I was wondering if some here had any simple home-brew recipes for a brush on or sprinkle on anti scale cocktail.

I've heard that roach killer,(99% boric acid) has some possibilities when sprinkled on the parts to be heat treated after they reach a temperature of about 600F but have no real experience with it.

I may have to go back to plan B if I can't find a quick solution for this as I hate dealing with the scale and the problems it brings.

mechaniac
10-11-2011, 01:43 AM
Hi Willy,
I'm using chalk sticks solved in water (thick solution) and dip the workpiece in this "Mud". Works fine and it's easy to clean with water. Sometimes it's necessary to apply several layers to cover the piece complete.

Greets,
Helmut

gary hart
10-11-2011, 01:54 AM
From some notes in my file, not sure of sources.

Heat gently, dip in borax, then heat treat to prevent scale.

Hardening w/out scale, bundle in wire, add boric acid w/alcohol.

Scale prevented by placing metal for furnace in sealed pipe.

Soft soap prevents scale and lets heat colors show through.

bob ward
10-11-2011, 08:39 AM
Also I understand that a number of effective over the counter products are available, but again that option too is not available due to the time constraints of ordering these products vs. when I need these parts heat treated.


For when procurement time isn't a problem, Rosemill's PBC anti scaling compound is very effective, they also make the Cherry Red case hardening powder. Available from the usual suspects.

http://www.rosemill.com/category_s/47.htm
http://www.rosemill.com/category_s/46.htm

gwilson
10-11-2011, 09:17 AM
There is an old recipe I have actually used,and it does work quite well,but you have to mix it up fresh every time or it will rot.

Take 1/2 cup of white flour and 1/2 teaspoon of yeast and a pinch of salt. Add water and stir into a fairly thick batter like for pancakes.

Paint this batter onto your parts and let it dry a bit. It will burn up,leaving a thick crust of carbon that will stay on the part while it is heated orange. It will smell like burnt bread while heating.

Stubbs,the well known file makers in the 19th.C.,used "beer leavings" to dip their files into,making a similar carbon crust to protect their files' teeth.

Old timers had to find simple but effective,and cheap solutions to their problems.

lazlo
10-11-2011, 04:52 PM
For when procurement time isn't a problem, Rosemill's PBC anti scaling compound is very effective,

PBC Anti-scale works. Satanite works too: make a thin slurry and brush on a thin coat.
I haven't tried ATC (Brownell's carries it) but have friends that have, and they say it works a lot better than PBC:

http://www.brownells.com/.aspx/pid=23076/product/ANTI_SCALE_COATING

I've got some Heathbath No-Carb on order -- about $3.50/lb. I'll let you know how it works out.

Stainless foil isn't going to help you on carbon steel. You can't quench the part in the foil (it doesn't transfer heat well enough), and you can't get the part out of the foil quick enough.
Stainless foil is *great* for air hardening steels like A2 and D2.

wierdscience
10-11-2011, 09:58 PM
Stainless foil isn't going to help you on carbon steel. You can't quench the part in the foil (it doesn't transfer heat well enough), and you can't get the part out of the foil quick enough.
Stainless foil is *great* for air hardening steels like A2 and D2.

Two words,Tin snips,the foil works fine,you just have to fold up an envelope so there is a flat end to chop.It takes two seconds to snip the end off and remove the part with tongs.

That said I only use foil on critical parts,day to day parts I use tin cans.

Two tin cans big enough to hold the part and a rolled sheet metal sleeve that just slips inside the cans.Put the sleeve in one can,put the part in,stuff the dead space with newspaper and slip the second can on the other end.

Heat the part,when ready to quench,grab each end with tongs,slip apart,be careful the newspaper now carbon may flash,fish out the part and quench.

Now all this hot stuff and fumbling with tongs can be made easier by having a 55 gal drum quench tank.It's big enough and deep enough to just drop parts in and let them sink,retrieve with magnet.:)

lazlo
10-11-2011, 10:31 PM
Two words,Tin snips,the foil works fine,you just have to fold up an envelope so there is a flat end to chop.It takes two seconds to snip the end off and remove the part with tongs.

Have you tested the hardness that way Darin?

With high carbon steel (1095, W1/W2) you have about half a second to get it from austentizing temperature to below the pearlite nose. So you have 1/2 a second to drop from 1475F to 800F

With alloy steels like 5160 you have about 5 seconds, O-1 around 9 seconds, so *much* greater margin for error (time to d!ck with the foil).

Willy
10-12-2011, 12:28 AM
Due to time constraints, (I had too much time into the parts);) , I elected to play it safe this time and managed to procure some ATP that Lazlo mentioned. It does work very well Lazlo, I couldn't ask for more.

Well, I didn't exactly procure it, I groveled for it from a gunsmith friend of mine.:D

But I would like to thank all of those that replied, some good suggestions.
And a big welcome to Mechaniac from Austria, I had not heard of the dissolved chalk paste before, but I'll give it a try.

I also want to give the bar of soap and boric acid/alcohol mixture a whirl.

Also George Wilson's suggestion sounds like just the ticket for first thing in the morning...if there's any left....well the heats on anyway, may as well make pancakes with the left overs.
If George says it works then I'll bet it does.

So when I get some slack time I'd like to give each one of these "cocktails" a go and see how they stack up. These home brew recipes are just the ticket for someone like me that just needs an anti-scaling compound every now and then.

wierdscience
10-12-2011, 01:29 AM
Have you tested the hardness that way Darin?

With high carbon steel (1095, W1/W2) you have about half a second to get it from austentizing temperature to below the pearlite nose. So you have 1/2 a second to drop from 1475F to 800F

With alloy steels like 5160 you have about 5 seconds, O-1 around 9 seconds, so *much* greater margin for error (time to d!ck with the foil).

Yes,people get pinchy with the foil,they wrap the part up tight like fruitcake in tinfoil that's why they have to fight with it.It costs money to heat treat,accept it.The envelope needs to be 3-4 times the size of the part,so a 3" round x 1" thick disc would need a envelope 8-10" square.I also use news paper in the foil bags just to be sure.IF you need more time fill the bag with vermiculite/pearlite or some scrap kaowool it will hold the heat in while you hamfist the thing open and ride your electric scooter over to the quench tank:D

I don't use anti-scale compounds or the homebrews.They work,but on complex parts they interfere with wetting which isn't good.