Thread: Standard Reference Material for Hanging Hair Test

A lot of the criticism about the use of the HHT to judge razor sharpness has been in the area of the incomparability between people, because the hairs used are different thicknesses, have more or less oil content, etc.

I've been thinking about how to instrument a sharpness test in order to get an objective, reproducible measure that will work at any stage of honing.

To this end, I've looked for replacements for human hair.

I focused on monofilament thread, as this would eliminate structure issues. I got some "invisible thread" in bobbins, with a thickness of 0.004" ( 0.1 mm). Unfortunately this is too light to let any razor I've sharpened cut it in a simple HHT. I will still try to use in an instrumented test or when I get a Lynn-honed razor back.

Another purchase was monofilament thread used in tying flies for fishing. This is Danville's Monofilament Fine, which is 0.006" (0.15 mm) diameter. It's available on ebay at

Danville Monofilament Thread Fine - Fly Tying - eBay (item 230507649553 end time Oct-03-10 14:34:03 PDT)

(auction #230507649553)

It's only $1.09 per 100 yd spool with $2.99 shipping. (I bought 6 spools to average out the shipping.) You might be able to buy it locally at a sports supply store.

This Danville's thread behaves very similar to the human hair I've been using for the HHT. It is slightly more resistant to cutting, but very close in properties.

The only issue is that it's clear, so somewhat hard to see in use.

The good news is that HHT results with this thread can be compared among members here with some idea that similar results should be expected.

I am continuing to look into colored versions of such thread, and into a possible test jig to standardize applied force or allow quantitative measurement.