Testing hardness with pencils

[Jay561]

Great thread, love the tips. Would of never thought of this.

[jws957]

Update to my post of 12/29/2012

I found that mixing about 9 lbs of recovered lead with 5.4lbs of linotype and 0.4 lbs tin gave bullets in the range of 2B to B for a "doesn't scratch" test. Used these in 45ACP loads and these didn't lead the barrels at all, while the slightly harder (B to HB) mix above did slightly, using the same powder/wt, etc. I also re-tested some of the recovered lead ingots and found that a 3B pencil didn't scratch. So I guess you can get a range of results with this method.

[Kull]

I used this method, as described my Molly and others, to test various alloys I got from Rotometals.

Rotometals Pure Lead - 6B, actually softer than 6B like someone else reported.
Rotometals 20/1 - 3B, as expected.
Rotometals Antimony Lead - 3B, same as 20/1.
Rotometals Hardball - HB, as expected.

Some Linotype pieces I just got from a fellow member and cast in to three pound ingots - F, for what it's worth.

The 20/1 vs Antimony Lead test to me shows it's not a test that can differentiate between 10 and 13 BHN, but it sure can narrow you down to one of four hardness levels. Super soft, soft, medium, and hard......now I want to watch Formula One. Pretty good method all things considered, can't beat it for 10 bucks.

[ken s]

one last thought. I'm a GIA Gemologist. diamonds etc. the old 'test a diamond if it scratches glass' well...on a MO's scale for gem hardness, diamond is a 10 and glass is a one. now..diamond, being harder WILL scratch glass, but so will GLASS being the same hardness.
basically, anything harder than the glass including glass will scratch it. so the 'test' is a bust.
pure lead will scratch pure lead, and so will anything harder.
so, if you use pure lead, and it scratches the lead you're testing, that should be pure lead...

[yamavira]

Any chance of a picture of the ideal point for a test pencil !!.

[Kull]

Any chance of a picture of the ideal point for a test pencil !!.

No point. Just cut off the core at a 90 degree angle. Like you would cut off a piece of pipe.

[Dale53]

Molly was my personal friend. He described the test to me exactly like Kull stated above. Just carefully remove the wood from around the end of a pencil of the appropriate hardness. Then, make certain that the end is right angles to the shank (carefully use a piece of abrasive paper, if necessary). It is important that the edge be sharp...

FWIW
Dale53

[BubbaJon]

Dunno how I missed this thread but I'm glad I found it. Went out after work and snagged a set of pencils. The two commercial boolits I had agreed with the manufacturers claim at 16 BHN (Dardas) and 20 BHN (lasercast). My alloy showed I was correct thinking it was a tad soft at 10 BHN.
Thanks to y'all clever folks I can stop guessing!

[mto7464]

picked some up on ebay for 12 bucks delivered.
http://www.ebay.com/itm/350744940919...84.m1439.l2649

[Teddy (punchie)]

Got a set of art (drawing) pencils. At PaT Catan's for five dollars.

Pure lead ; tested at 4B , 5B and 6B too soft.
Wheel weights; tested at H . Range Lead HB just a little softer then WW.

This pure lead; is 100 % pure was given to me years ago we were leading cabinets for medical field so had to be pure.

Was very easy to tell the difference in just the way if feels, with the pencil core going over the different metal.

[TenTea]

Thanks to all who posted here, as this thread has been an exceedingly helpful and interesting read.

I will begin Staedtler testing forthwith!

[Newshooter]

very useful information here. Thanks to everyone.

[destrux]

I read several time concerns from people who haven't tried this method about the effect of pressure and method on repeatability.

What I've observed in doing this is that as I work down in pencil hardness each pencil will scratch the test alloy just as easily as the last pencil did, till I reach the pencil that won't. Then no matter how much pressure or what angle I hold it at, it simply won't gouge the alloy. The pencil crumbles when you attempt to scratch alloy that's harder than the pencil is.

I've found it's easiest to simply use a pencil sharpener to get a sharp point on the pencil, then I try to gouge it into the surface at an angle, roughly 45 degrees. If it gouges, it gouges, if it doesn't, it crumbles and slides. Simple, and repeatable.

My results coincide with what others using other pencil methods have posted.

I tested some pure lead and found it to be softer than 8B.

Some stick-on WW ingots tested at 5B.

Clip-on WW ingots tested at HB

Water dropped clip-on WW bullets with 2% tin tested at 2H.

I got my pencils at Wal-mart, they were about $7 if I recall. They have the ASTM emblem on the back.

[JWFilips]

I would also like to note:
I have tried a number of different quality ( or not ) pencils sets & it appears that Staedtler is the more accurate for the purpose.
I tried others which gave lower readings and also higher readings with known samples of lead & lead alloy.
The Staedtler's seem to be right on ( & I feel can be trusted) to get you very close to the hardness you are testing.

Unfortunately I tried to save a buck in the begining and bought the lower price sets but noticed they didn't match what my borrowed Staedtlers were showing. I even went so far as to buy a more expensive brand because the art store was out of Staedtlers They too didn't get me as close Glad I finally got the true testing set. Save yourself some aggravation

[40-82 hiker]

Thanks, Molly and Rob. This is useful information. As I begin to gather data from using my new pencil set on samples from my store of boolit alloys, I am beginning to map out a scale of sorts - call it the Staedtler Scale, after the makers of these fine artist's pencils. So long as one sticks to that widely available brand of pencils and uses the correct technique, results will be similar. Molly observed spacing of about 1-3/4 BHN between some of the grades, perhaps at the softer end of the scale. Here's what I've gathered so far:

6B = Pure lead, about 5 BHN
5B
4B
3B = 1in20 tin/lead alloy, age softened, about 10 BHN
2B
B
HB = Lyman no 2 alloy, about 15 BHN
H = Linotype, supposedly about 22 BHN, but that seems high
2H
3H
4H

I offer this cheap but effective method of testing relative hardness, not particularly to convert pencil numbers to Brinell numbers, but rather as an alternate scale for boolit casters, with reference points to known alloys. If I pick up some scrap lead, or buy alloy from a smelter, I can quickly find out where it lies, relative to those other alloys. For example, my small stock of LaserCast brand commercial lead projectiles tested HB. I never had any luck with them, I've been saving them for the furnace, now I know approximately where they fit in as feedstock.

The bullets I cast from Lyman no 2 do very well in my rifles, with no leading at all. But methinks that alloy is too hard to maintain a tight seal in my revolver loads. So I'll try some of the 1in20 alloy, maybe with some Lino mixed in to boost it up into the 2B range. - CW

You are correct in recommending that brand of pencils ONLY to go with your research. Pencil manufacturers readily admit there is no industry standard for pencil hardness. They all use the same relative hardness designation, but they really only mean that one is harder or softer than another along an understandable scale. An "H" pencil from one manufacturer is not the same as from another, unless purely by chance. I ran into this problem in another venue a couple of years ago, and it caused me much frustration until I came upon this information.

Thanks for the research.

[seyoncorey]

I have read the entire thread and have been impressed!

I was at my local wally and found a set of pencils for $5 bucks. I tried them out on my WW lead and my pure lead and my mystery lead.

My WW lead came out to a HB, my pure lead came out to a 8B/6B, and the mystery lead came to B. This seems to be consistent to what has been reported so far.

My WW lead came from a 5 gallon bucket of weights I have collected for years so I know it came from WW. The pure lead came from a 40's ish 20kg calibration weight I found in the trash, lastly the mystery lead came from a race car friend of my that said it was old car weights.

My question is.. Do these values make sense to what you have all seen, and can anyone make sense of what old car racing weights are?

Thanks to everyone here!! I have come here many times to get advise as I am new to casting. This is a great place and many thanks to the people that share their experience and information.

[popper]

Think I finally got my hardness/toughness tester figured out. Wish I could use a torque wrench for measurement, but!! Cut an RCBS deprimer pin so it is 0.020" out from the holder. Screw it back into the sizer die I don't use anymore. Put a CB on the press and measure the force to push the pin all the way into the CB, the holder stops so I only go in 0.020". Use a fish scale to measure the force on the handle. Won't calibrate to BHN but will give a relative reference for my alloys and heat treating effects. So far, ~ 20-25 #. I just watch the scale and see what the # is just before it pops. Don't have to file or polish anything, no magnifying glass.
Edit: Tried a different approach, used a 9mm case in the 9mm die, adjusted the standard pin down 0.020". Tried several CBs, numbers came out the same. Difference in alloy is just different batches.
alloy #1
30-30 RD 180 23#
40SW A 165 22#
30-30 RD 180 14# Hi-Tek coated, HT 1 hr @ 250F

alloy #2
308 A 165 32# powder coated, HT 30 min @ 450F

Scale is a $20 berkley digital, 50# max. Press is a Lee classic cast.
Now I can validate different batches & casts. I can get a lot of lead for the >$100 for a tester.

[GunFun]

Air cooled ingots from lead pipe cut with 3B.

Bullets I got severe leading with tested to B

[popper]

First letter is for hardness, second is for blackness. I've used the Pentel version as you don't have to cut anything.

[DougGuy]

I too enjoyed this thread and invested in the Mars Staedtler Lumograph set, about $12 at Staples. I was looking at deciding on two different hardness levels for hunting boolits.

The boolit is dropped from the Lee C430-310-RF mold, it is their wide flat nose gas check design in .44 caliber. I use the softer one for deer, bear, thin skinned animals and I run it out of the muzzle about 1100f/s or so. The slightly harder alloy I push harder, 1300f/s and it is used for pigs.

One alloy is 50/50 coww and pure lead, with 2% tin added, it is the softer one that I can scratch with a thumbnail, it is a 3B, or BHN 10.

The other alloy is straight acww, can't scratch it with a thumbnail, it is a B, or BHN 14.

I didn't -really- need two specifically different alloys, could have done all my hunting with the acww, it was just something that interested me at the time, and I found the pencils a great aid in this effort.