Lead hardness pencil test

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March 28th, 2022, 01:19 PM
MikePal

Lead hardness pencil test

Thought I'd share this method I found for doing a quick and easy test on your raw lead to determine it's hardness.

I picked up a 4 pack (2B,3B,4B,6B) of Staedtler drafting pencils at Staples for about $8.

I ran them, as per instructions below, over my lead ingots and was surprised how well this works.

Quote:

LEAD HARDNESS PENCIL TEST

Start by selecting or flattening a small section of the lead alloy surface with a file. The base of a large caliber bullet is sufficient. Prepare the pencils by peeling or removing any wood for a short distance away from the tip, leaving a short exposed section without any taper. Next, sand a flat surface on the tip with a file or 500-600 grit sandpaper, being sure to completely remove any taper. The exposed section should now be a short rod with straight sides, a flat
tip with sharp 90 degree edges.

From the chart below, select a pencil that you believe to be softer than the alloy. Hold the pencil at 45 degrees to the lead alloy surface and press firmly forward along the axis of the pencil with the sharp edge. If the pencil skids over the alloy surface, even if it leaves a
slight scratch, it’s softer than the lead alloy. Work your way up to progressively harder pencils until you get to one where the sharp edge digs into the surface, pushing up a curl or mound of alloy in front of it. Using the largely subjective cross reference chart below, the
hardest pencil that will NOT dig into the alloy is used to determine of the hardness of the alloy in question.

Note: BHN; lead alloy Brinell Hardness Number
Note: WW (wheel weights)

https://i.imgur.com/ClN4EqS.png
April 1st, 2022, 05:41 PM
FishHog

Good stuff mike
I’ll have to give that a try
Thanks for sharing
April 2nd, 2022, 08:35 AM
Muskyhunter

That is great stuff.

Thank you for sharing. I bought a Lee Lead tester and haven't got around to using it yet. This looks more simple and faster.
April 2nd, 2022, 05:02 PM
MikePal

The only tricky part of the whole exercise is to trim off the taper of the lead and then back off the wood to leave a small cylinder of lead with 90% edges. It's hard not to damage the lead with the Exacto blade. The first time I used to thick a blade and broke the wood unevenly. Ended up using a real small Exacto knife to keep it neat.

I had ended up with two batches of ingots, one tested to 10BN and the other 11-12BN. This is the perfect hardness for the Minnie Balls I plan to cast. If the lead is too soft, it's too easy to damage the skirt.
April 3rd, 2022, 06:48 AM
Big Jack

I’ve used the lee tester and it really can’t get much easier! No guessing and it seems consistent
April 3rd, 2022, 03:50 PM
MikePal

Quote:

Originally Posted by Big Jack

I’ve used the lee tester and it really can’t get much easier! No guessing and it seems consistent

Hey Jack...that was going to be my first route...but when I saw the price $150 (Amazon.ca), I decided to look for a more pragmatic approach. I don't do this enough to make a big investment, so the $8 at Stapels was far more palatable. :)