Thread: Thiers Issard grades

hmm...I dont know if I like the idea of lead possibly getting into my blood stream. Is this why its illegal in some countries? I understand the idea of putting graphite between the steel and lead as a barrier since it has a much higher melting temperature, but it still makes me a bit nervous. Of course I have never heard of a straight user getting lead poisening from a razor.

Originally Posted by JLStorm

hmm...I dont know if I like the idea of lead possibly getting into my blood stream. Is this why its illegal in some countries?

I think the're more worried about the conditions for the workers. I don't think the lead bonds with the steel at all so you should be safe.

X

Originally Posted by JLStorm

....Of course I have never heard of a straight user getting lead poisening from a razor.

That's because all you heard was, "I don't feel that goo.........."(THUMP!)



C utz

Originally Posted by randydance062449

One of the books I have on hardening steel stated that mercury would be better but it was to expe3nsive.

And even more toxic!

Originally Posted by JLStorm

...Is this why its illegal in some countries? I understand the idea of putting graphite between the steel and lead as a barrier since it has a much higher melting temperature, but it still makes me a bit nervous. Of course I have never heard of a straight user getting lead poisening from a razor.

Gentlemen, allow me a moment. The melting temperature of lead is 600 F/327.5 C. The temperature of 850 C/1560 F would be an acceptable heat treatment temperature but far too high for a tempering temperature (around 400 F/205 C).

The most likely use, is to austenitize the steel, put all the carbon into solution and quench from that temperature. A molten bath, whether lead or high temperature salts (my choice, dangerous but not from nasty fumes) will be very easy to control temperature wise and reduce the risk of grain growth and other problems occuring when the austenitizing temperature is overshot. Frankly, the steel doesn't really care which method, of them all, is used.

The real purpose of both the graphite and lead (and so will molten salt baths) is to prevent oxidation at that temperature (scale formation). This is very desirable for production because the blade can be nearly completely polished and subsequently heat treated without any further grinding to clean up the steel.

The problems in production are the lead fumes that will cause nervous system issues. So the Euro equivalent of OSHA comes in to play. The steel, if finished sufficiently well, will not pick up any lead in quantity and unless someone is daring enough to routinely lick their blades, doubtful that enough will be ingested to make any difference. We're all nuts enough using straight razors to shave with eh?

Thanks Mike. That was useful.

So why do you think is it that they choose to use lead? Cheaper? Easier?

X

I suspect historically that it was both. Lead was a pretty well known compound since the Roman era, very easy to work and work with. The plus side, they had no idea of its health hazards as we do now. As a metal it's pretty sturdy, easy to shape, easy to cast with it's low melting temperature.

Whoever figured out that a piece of steel could be heat treated with little or no scale was an observant fellow indeed. Made for very consistent heat treatment. Hence the TI reputation. It would be really interesting from a history standpoint to know when molten lead became a part of the heat treatment industry.

Originally Posted by Mike Blue

The melting temperature of lead is 600 F/327.5 C. The temperature of 850 C/1560 F would be an acceptable heat treatment temperature but far too high for a tempering temperature (around 400 F/205 C).

TI says they "lead harden" at 800 C then anneal at 300C.

Joe,
Those numbers would be inline with hardening and annealing good steel and similar to what Mike has stated.

Tony

I'm going along with the info you guys are telling me. It's interesting to "look into" their processes though. Are there TI references for me to look at? It might not be all that interesting to the list here, but little tidbits might pop into my head.