Originally Posted by
Dr.Phil
I'm new to this forum & casting but would like to thank everyone for providing such a valuble resource.
I'm putting the information aquired from this thread into my casting notes.
Here is what I have so far:
Lead Hardness Testing using the Staedtler scale
Staedtler Hardness Chart:
8B Sheet lead
7B
6B Lead wire 5 BHN
5B 40/1 lead / tin
4B
3B 1/20 tin/lead 10 BHN
3B Clip-on WW
2B Range scrap
B 20/1 Lead / tin
B Quenched range scrap
B Air cooled WW
B WW+2% tin
HB Lyman #2 15 Bhn
F Lyman #2
F Commercial cast
H 50/50 Lino /WW
H Linotype 20 Bhn
2H Quenched WW
2H Monotype
3H
4H
Rough BHN to Staedtler Hardness Conversion Chart:
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
Testing Protocol:
The correct way of using the pencils is to find the softest pencil that will CUT INTO the surface. You should be able to see a tiny curl or chip of lead that is peeled out of the surface."
Start by flattening a small section of the alloy surface with a file. The base of a large caliber bullet is sufficient. Peel the wood away from the graphite core of the pencil, which is a thin rod. Then sand the tip of that rod to a 90 degree angle by rubbing it across a sheet of 500 or 600 grit sandpaper while holding it straight up and down. If the pencil skids over the alloy surface, even if it leaves a slight scratch, its still not harder than the lead alloy.
The hold the pencil at a 45 degree angle with the surface you are testing, and push down along the length of the pencil, as if you are trying to shove a knife point into the surface. If you try to push the pencil across the surface as if you are writing on in, you will get a much 'softer' result, because the edge won't be cutting into the surface, it will just be rubbing across the surface.
Work your way up to progressively harder pencils, until you get to one where the sharp edge of the pencil "meplat" really digs into the surface, pushing up a curl or mound of alloy in front of it. At that point you stop and consider the hardest pencil that will not dig into the alloy in this manner, to be the "Staedtler" rating of the alloy in question.
For example, my little store of 1in20 (tin-lead) alloy skids on a 3B but digs in on a 2B, therefore its Staedtler hardness is 3B. Some Hornady swaged lead bullets I have will skid on 4B but dig in on 3B, therefore the Staedtler hardness rating is 4B. I also suggest we stick to the Staedtler Mars Lumograph pencil sets, since the maker claims they conform to ASTM standard D-4236 for consistency. They are cheap and readily available at Office Depot and other stores.
If any of this information is incorrect or if anyone thinks there should be additional information included, please let me know and I will update this post to reflect it.
This way any new users can get everything they need in one spot without having to assemble it from several pages of posts.