# Strength of PMC



## Proud_Poppa_of_2 (Mar 7, 2008)

In this  thread, I had questioned the viability of silver precious metal clay (PMC) for use as a pen clip due to its presumed lack of tensile strength.  George suggested I do a little research into PMC's strength characteristics and report back.

I had done that some time ago, as I thought PMC might be one avenue for freeing us from kit nibs and clips.  My research led me nowhere, however, other than anecdotal references to PMC's weakness due to its inherent lack of density.  At George's behest, I gave the research another whack, and came up with an article entitled  "Make Your Own Oil Paste" (top of page 5) published by the PMC Guild.  While the article does not address the issue directly, you can see that PMC is some darned strong stuff.

Of course, I'd like George to make his PMC clip and tell us what he thinks of its strength, but it appears that, under normal use, a pen clip ought to survive.  My next question is, will the threads on a PMC nib survive shearing forces?


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## alamocdc (Mar 7, 2008)

Very interesting read indeed, Mike. Thanks! Wading through everything the PMC Guild has to offer can be somewhat daunting. But it's certainly educational.


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## DCBluesman (Mar 7, 2008)

I would not be at all concerned about tensile strength (defined as the maximum tension the material can withstand without tearing), but would be very concerned with the spring strength.  PMC leaves .999 silver behind.  The reason table ware is made from sterling silver (92.5% silver, 7.5% copper) is due to the fact that silver bends quite easily and does not spring back.  The copper hardens the silver, making bending it quite difficult.  I'm not being a naysayer as I am eager to hear the results from George's efforts.


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## its_virgil (Mar 7, 2008)

I seem to remember someone trying to make pen parts from PMC once before...maybe I'll do some searching to see if I can find it. Anyone else have recollections on this topic?
Do a good turn daily!
Don


> _Originally posted by DCBluesman_
> 
> I would not be at all concerned about tensile strength (defined as the maximum tension the material can withstand without tearing), but would be very concerned with the spring strength.  PMC leaves .999 silver behind.  The reason table ware is made from sterling silver (92.5% silver, 7.5% copper) is due to the fact that silver bends quite easily and does not spring back.  The copper hardens the silver, making bending it quite difficult.  I'm not being a naysayer as I am eager to hear the results from George's efforts.


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## Texatdurango (Mar 7, 2008)

> _Originally posted by Proud_Poppa_of_2_
> 
> ...and came up with an article entitled  "Make Your Own Oil Paste" (top of page 5) published by the PMC Guild.  While the article does not address the issue directly, you can see that PMC is some darned strong stuff.
> 
> ... My next question is, will the threads on a PMC nib survive shearing forces?


I just read some of the article and need to look into the lavender oil!  Appreciate the link.

So, are you saying that you are going to be working on making a PMC nib?  Wow we've got ourselves a team now! []


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## Proud_Poppa_of_2 (Mar 7, 2008)

> _Originally posted by Texatdurango_
> 
> So, are you saying that you are going to be working on making a PMC nib?  Wow we've got ourselves a team now! []



No, Chuckie is gonna be working on the PMC nib.  He just doesn't know it yet.  [}]


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## PR_Princess (Mar 7, 2008)

George, 

I have this Lavender oil. PM me if you would like me to send you some to play with.[8D]


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## Chuck Key (Mar 7, 2008)

> _Originally posted by Proud_Poppa_of_2_
> 
> 
> 
> No, Chuckie is gonna be working on the PMC nib.  He just doesn't know it yet.  [}]



Whatsa nib look like? [8)][:I]

[^]Chuckie[^]


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## jjudge (Mar 7, 2008)

My order of PMC silver clay came in 2 weeks ago ... and PMC paper.
I'd not planned to do a pen part, but to fold the paper into a pen rest (misspent youth taking origami classes)
So, I had no real plans for the clay. 

I'll watch this forum -- maybe I can help figure something out with the clay I have.

-- joe


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## bitshird (Mar 7, 2008)

My only question about using silver in any form be it cast, fabricated, or from PMC,  while the PMC does have nearly the same strength modulus and shear resistance, silver is soft even .925 .
 There is a spring silver available in sheet, but if you solder it with silver solder you have to heat it to at least 950 F. and that solder (extra easy) leaves a definite difference in color and anneals the silver, I can cast the Nib and center band or trim bands for caps, but dealing with the clips has been my bugga boo.
 After seeing Georges idea this morning, I think I can over come the problem by making a mold of the clip with a low shrinkage silicone rubber, cast it in Sterling.
 Then tumble it in stainless shot in a vibratory tumbler for about 12 to 16 hours  that should  work harden the silver  harder than even spring sterling sheet the tumbling should have the same effect on PMC as well, it would actually be work hardening the silver by molecular compression.
 I'm off next week and have every thing to do it with, I just wish it wasn't snowing tonight, I've been thinking about this all day  [] []
Sorry to get so drawn out but I've been trying to figure this clip thing out since about 3 months before I started turning pens last fall.


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## PenWorks (Mar 7, 2008)

PMC is pretty strong stuff. In the class I took, you messure the thickness of your work by playing cards. 1 through 5.
A 3 thickness, is the width of three playing cards taped together. You roll your PMC to that thickness. I found anything 3 or higher is not bendable after it is fired.


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## Rifleman1776 (Mar 8, 2008)

> _Originally posted by PenWorks_
> 
> PMC is pretty strong stuff. In the class I took, you messure the thickness of your work by playing cards. 1 through 5.
> A 3 thickness, is the width of three playing cards taped together. You roll your PMC to that thickness. I found anything 3 or higher is not bendable after it is fired.



  "not bendable" Does that mean it is brittle?


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## PenWorks (Mar 8, 2008)

Frank, I did not find it brittle. If rolled to a 1 or 2 thickness, I found you could bend it with your hands after fired.


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## jrc (Mar 8, 2008)

Been working with PMC clay for a while and do not think it would make a good clip but yesterday I was trying out the sheet and found it very thin but somewhat flexable.  I have read that you can lightly dampen the sheet and lay a second peice on top and place a piece of glass or something flat with alittle weight on it and double the thickness. This might work.  Myself I'm never afraid to try something different, you can only learn from a mistake.  Why not make a pen just for the desk then you do not need a clip.


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