TIG electrodes: thoria vs lanthanum

I'm about to make my annual pigrimage to the welding supply store. Very soon I'm going to be doing a lot of critical TIG welds (fillets)
in 3/16" A36 or A500 steel.
I've read that the 2% thoria is added to enhance then current carrying capacity of the electrode, but the radioactivity scares me even if it's pretty low level. Would I be sacrificing anything if I switched to the lanthanum types? Should I get the yellow or the black?
--zeb
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Lanthanated tungstens are better than Thoriated tungstens in every way. They handle more current on DC and are far superior on AC to Thoriated.
Lanthanated tungstens come in 3 flavors. 1% - Black band 1.5% - Gold band 2% - Blue Band.
2% Blues are kind of rare still.
I find the gold band 1.5% lanthanated tungstens are the best for general use.
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Ernie, i've never seen thoriated used for AC or recommended for AC.
i use zirconiated for AC TIG. can you give a short on each and what you use them for (ac, dc, stainless, etc):
thoriated zirconiated pure lanthanated ceriated
wrote:

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Commonly used for DC, and sometimes used on AC when you need to get into tight spots, but a poor choice. On AC the tip can deteriorate rapidly causing tungsten inclusions in the weld. Will also work on DCEP aluminum.

Only used for AC, and capable of carrying the highest current of any tungsten on AC. Never use on DC as they will disintegrate rapidly.

Only useful for low amperage AC. Very poor current carrying capacity, but a very smooth arc.

Equally good on AC or DC, also good for DCEP aluminum. Highest DC current capacity of any tungsten. Very smooth arc, excellent arc control.

Equally good on AC or DC. Ceriated tungstens can initiate an arc at lower amperages than any tungsten. Very smooth arc. Not recommended for high amperages as they deteriorate rapidly.

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2% lanthanated are available for fairly cheap from AGLevTech: http://www.aglevtech.com/LANTHANATED_Tungsten.html
I've been using thoriated (red) tungsten for the last week or so because that's what came with my ThermalArc 185. I do hope that having ground them once inside without a dust mask doesn't mean I'll die of cancer in a few years...
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Thoria is not a hazard to hobbyists. It is a very low yield alpa-emitter, and is only really dangerous to guys working in big pipe shops grinding tungstens every day for years.
Still, avoiding exposure to it can only be a good thing. I haven't bought Thoriated, or pure, tungstens for about 10 years. I have never missed them.
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Thorium is a alpha emmitter and poses no hazard as long as you do not ingest any of the dust.
Dan
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snipped-for-privacy@krl.org wrote:

Right - alpha won't go through paper or the skin. It can attack the fragile skin of the lung. Finger skin is thick and dense.
Another item is half life - the time that it takes to weigh 1/2 of the initial amount.
It is extremely long - 1.4 x 10^10 sec. Plutonium is shorter!
So once in the lung, it keeps sending alpha at you. Alpha is He or the gas in balloons with a radioactive attitude.
This is one of the reasons a soft coal (look out blacksmiths) power plants were more dangerous than a nuke. Soft coal contains Thorium naturally. It is used on vacuum tube filaments for the power supply tubes for extra current as well.
Earlier someone mentioned a wet or water stone to cut it - seems logical. Dispose of the cuttings in an active method rather than on Fridays when I do it... Keeping safety on the safe side.
Martin
--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer snipped-for-privacy@pacbell.net
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such as breathing the dust. A wet grinder will reduce/eliminate the risk.
I haven't found a downside to lanthanum yet. It may spit and wear a bit quicker than thorium.
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snipped-for-privacy@hotmail.com wrote:

If it makes a difference to anyone....We have just banned thoriated tungstens at my place of employment (pulp and paper mill)and are now in the process of determining the best way to clean up shops where TIG was done and these electrodes have been ground on belt sanders and grinding wheels. The dust IS hazardous and it does not take very much at all to pose a health hazard. A little bit here and a little bit there adds up to a lot over time. There are alternatives that give good results...we are also in the process of determining what the best alternative is. I let you know when we do.
Sean
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1.5% Lanthanted are the best general purpose tungstens.
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it what you have exceeding some EPA/OSHA or health regulations? just wondering if you are over the limit or just being health concious...
wrote:

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Kryptoknight wrote:

We have not done any detection at this point but the information we have and the availability of alternatives lends itself to replacing these tungstens now. It was simply brought up that in some shops where the dust collection was not the best may have some residual radioactive material around the grinder or....everywhere.
Sean

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The results of a MedLine search on thorium shows that there are no studies that I could find that showed a pathology due to TIG welding with thoriated tungsten. A couple of studies showed higher exposure during welding compared with grinding which is counter-intuitive but interesting. Only one French study recommends banning thoriated tungstens and their reason was simply that alternatives are available.
As far as I can find, neither OSHA nor NIOSH has an exposure limit for thorium.
The only sites I can find that warn strongly about thoriated tungsten exposure are run by law firms or air purification companies.
Cheers,
Kelley

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I don't buy Thoriated tungstens because they just aren't as good as Lanthanated and Zirconiated tungstens.
Why people keep buying Thoriated and Pure tungstens is just beyond my comprehension. Especially pures......yuchhhh!

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On Thu, 24 Feb 2005 09:05:53 GMT, Ernie Leimkuhler

C'mon Ernie, tell us what you REALLY think !! (grin)

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Have you tried any of the new blends?
-J
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The only blend tungsten I have seen is Huntingdon Fusion's Triple Strike tungsten with 3 doping agents. Likely Ceria, Lanthana and Zirconia.
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I agree completely Ernie. By the same token, when claims are made that there are medical safety reasons to not use thoriated tungstens I have to look it up.
Cheers,
Kelley
On Thu, 24 Feb 2005 09:05:53 GMT, Ernie Leimkuhler

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Hey those medical claims serve a very important function.
They help sell a lot of $700 tungsten grinders with kerosene bath dust collection.

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