Over Cooked Linotype

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  • Last Post 26 January 2022
John Alexander posted this 25 January 2022

Detective Callahan says that; " a man's gotta know his limitations". I try to keep that in mind as I get more and more likely to put things down where I can't find them, lose focus, and commit other geezer acts.  However, that is a work in progress.

I thought I had safeguards in place to prevent me leaving the shop with the melting pot on, but they didn't work and I left a pot of linotype at about  730 F on for at least two and maybe three days when I didn't go into the shop. I usually put a layer of kitty litter on top of the melt to slow oxidation but for unknown reason I hadn't.

When I discovered my stupidity, the top was covered with a black layer.  The only thing I thought of was to flux the pot with a double helping of NEI "FLUX". In doing this, that top layer turned out to be an eighth inch thick of a weak solid. I stirred in hopes getting the solid material to melt back into the rest of the now unknown alloy without noticeable luck. I then skimmed it off and it felt heavier than expected, near the density of lead.

I haven't tried casting bullets with the remaining alloy yet but I did cast a ingot for hardness testing. The ingot showed a BHN of 20 by LBT tester -- the same as the linotype tested before melting.

I wish Bill Ferguson or Dennis Marshall was still with us. Does anybody know what has happened. What parts of the linotype I have lost in the discarded solid material? What effect will the loss have on the remaining alloy.

All advice welcomed.

John

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RicinYakima posted this 25 January 2022

I went to my favorite materials chemistry website, and think that it is a "mixed metal amorphous oxide". Tin will oxidized pretty rapidly at that temperature, so you would have a thick layer of tin oxide cutting off the  air from the surface. However, the lead just under that layer would try to combine with the bottom of the tin oxide by stealing some of the oxygen from the tin. 

As you know, at 730 degrees, the linotype is a true liquid solution, but at the molecular level, the three metals are constantly trying to arrange themselves to their electronic crystalline form. Not having enough oxygen for each atom to have the required amount to stand alone as a metal oxide molecule; the metals are surrounding the oxygen trying to share the electrovalence difference. 

I think the black material is most of the tin in the original alloy, lead being the second most metal and antimony the least. The would make the hardness close to just a lead/antimony alloy with little or no tin. The black color may simple be the carbon remains of whatever flux had been used in the crucible since it was last cleaned down to the metal. 

FWIW, IMHO

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John Alexander posted this 25 January 2022

Thanks for looking into it Ric. Very clear and understandable explanation and one that seems to fit the symptoms. I will first try to cast with it as is and if that works (I don't expect it to work as well as linotype) I will use.  If it is hard to cast good bullets I will add tin and try again. I will report my results, or lack thereof.

John

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Spindrift posted this 25 January 2022

The worst thing that can happen if you cast bullets with this alloy, is if it works better than any alloy you’ve tried before. Imagine the troubles, having to reproduce it 🙂

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MP1886 posted this 26 January 2022

Using Johns description, little can be known about the original alloy.  He mentions linotype but he does not describe it in any way.  How used the linotype is can be very important. Had the linotype been used only a few times or for several years? This can make a big difference.  This longer term melt condition can be greatly affected by the time at melt. He states 2 and maybe 3 days.   He mentioned Linotype.  It is common for Monotype to be mixed together with Linotype and in this case, you would have to know how much.   Monotype is harder than linotype.  It can have some calcium and aluminum in it.  It is harder than linotype.

 

In John’s description, we have no idea what is in the pot exactly.  Staying molten for two or three days will allow separation of the tin, lead and antinomy.   So you will have oxides of all three.   That makes up that crust.

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John Alexander posted this 26 January 2022

Thank you for the lecture on the evils of assuming that just any ol' shiny lead kinda stuff is linotype as well as the evils of imprecise writing.  I should have mentioned that it wasn't straight from a vendor certified Linotype but lower case linotype in half Hershey bar sized plates with printing on one edge.

Apparently the printer thought it was close enough to Linotype to use and the bullets I cast from the unknown stuff don't seem to know the difference. I didn't ask for a chemical analysis of what the crusty stuff might be just some idea our of curiosity. Ric did a good job of that.

Astute readers probably noticed that a hardness test indicated that there probably wasn't much Monotype involved.

John

 

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TRKakaCatWhisperer posted this 26 January 2022

Back in the day I had some good conversations with a editor/printer of a small town newspaper.  His comments on linotype (he had at least two machines) was that he would have to replenish the antimony and tin periodically that would 'burn out' over time.

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John Alexander posted this 26 January 2022

You are right. The local printer back in Maine would even send off the nasty material skimmed off when fluxing to have the metal in it salvaged for reuse.  This was back in the day when we recycled more -- milk, coke, and other bottles etc. Now things come in indestructible plastic that is dangerous to open to get the product out and then is dangerous to us all for hundreds of years in one way or another. Are we sure that is progress? Well, at least it is profitable for the companies making the stuff.

John

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